Quantum Computing Research Archive

Guest Post: How Tokenized Finance Can Prepare for Post-Quantum Security

Tue, 08 Sep 2026 00:00:00 +0000

Guest Post by Edwin Mata, Co-Founder and CEO of Brickken Building financial infrastructure is strange: you have to make decisions today for assets that may still exist long after the underlying technology has changed. That is especially true in tokenization because a bond issued on-chain today might mature in twenty years. An interest in a private company could sit on a cap table for decades. Real estate, private credit, funds and other assets being brought on-chain involve legal rights and economic relationships that can persist for a very long time. So when we talk about quantum computing and finance, I think the useful question is not when a sufficiently powerful quantum computer will arrive. I do not know, and I am skeptical of anyone who gives you a precise date. The alternative question is much more practical: are we building tokenized financial infrastructure that can evolve when the cryptography securing it needs to evolve? I think we can, but only if we build adaptability into the architecture now. An asset may need to outlive the technology supporting it. We have already seen this problem, on a smaller scale, throughout the history of technology: protocols change, securit

A cascaded random access quantum memory

Tue, 08 Sep 2026 00:00:00 +0000

Fujitsu develops diamond-spin quantum computer prototype

Tue, 08 Sep 2026 00:00:00 +0000

Insider Brief Fujitsu developed what it describes as the world’s first working diamond-spin quantum computer prototype integrating tin-vacancy centers with photonic circuits. The prototype operates at minus 271.6 degrees Celsius and can be accessed through Fujitsu ’s Hybrid Quantum Computing Platform. Fujitsu plans to develop a multi-module prototype by 2027 and is exploring integration with superconducting quantum computers. Image: The diamond-spin quantum computer prototype. ( Fujitsu ) PRESS RELEASE — Fujitsu today announced that it has developed the world’s first working prototype of a diamond-spin quantum computer incorporating tin-vacancy (SnV) centers into photonic integrated circuits [1] [2]. The prototype can be operated at -271.6°C, higher than the typical operating temperature of superconducting quantum computers (-273.13°C) and Fujitsu has demonstrated in a test environment that it can be utilized via the Fujitsu Hybrid Quantum Computing Platform without any additional specialist knowledge. This development represents an important milestone toward realizing a modular architecture, one of the most promising approaches for scaling quantum computers, due to its high

Singapore, Luxembourg Target Deeper Cooperation in Quantum, AI And Space

Tue, 08 Sep 2026 00:00:00 +0000

Insider Brief Singapore and Luxembourg plan to deepen cooperation in quantum computing, artificial intelligence, space technology and satellite communications. The countries are major financial hubs with strong investment ties and limited domestic markets. Their leaders also discussed closer ASEAN-EU relations and support for international stability, trade and the rule of law. Singapore and Luxembourg plan to deepen cooperation in quantum computing, artificial intelligence, space technology and satellite communications as the two small, trade-dependent nations seek closer economic and strategic ties. Singapore Prime Minister Lawrence Wong identified the technologies as emerging and critical areas for collaboration during an official lunch for Luxembourg Prime Minister Luc Frieden on Sept. 7, according to Asia News Network . Frieden was visiting Singapore from Sept. 6 to 8, his first official trip to the country since becoming prime minister. The visit also followed Luxembourg’s opening of its first resident embassy in Singapore, a step Wong described as a “strong signal” of Luxembourg’s commitment to greater engagement with Singapore and Southeast Asia. The proposed technology coop

Structured light–matter interaction in semiconductor cavity quantum electrodynamics

Tue, 08 Sep 2026 00:00:00 +0000

Entangled particles revive a 35-year-old test of the Standard Model

Mon, 07 Sep 2026 00:00:00 +0000

Physicists at the BESIII Collaboration have breathed new life into a decades-old test of one of the Standard Model's most important ideas, using a technique that had gone almost untouched by experimenters for 35 years.

India’s Global Fintech Fest 2026 to Highlight Quantum Technology, AI and Tokenization

Mon, 07 Sep 2026 00:00:00 +0000

Insider Brief India’s Global Fintech Fest 2026 is set to open in Mumbai on September 8, with quantum technology, agentic AI and tokenization among the main topics on the agenda. The four-day event will bring together regulators, financial institutions, technology companies, investors and academics to discuss emerging technologies and financial systems. Maharashtra officials are positioning Mumbai as a fintech hub, citing the state’s startup and investment activity, data-center capacity and fintech-specific policies. Photo from Unsplash by Rahul Sapra . Prime Minister Narendra Modi is set to open the seventh Global Fintech Fest (GFF) in Mumbai on Tuesday, kicking off a four-day programme running September 8 through 11 that brings together regulators, financial institutions, technology firms, investors, and academics, the Free Press Journal reported . The event, which has run annually since 2020, carries the theme “Potential to Impact: Agentic AI, Tokenisation, Quantum – Trusted, Connected, Global Systems for Inclusive Finance.” Organizers said sessions will focus on how agentic AI, programmable finance, quantum technologies, and other emerging fields can produce me

NEC Discontinues Superconducting Quantum Computer Development to Focus on Annealing and Classical Emulation

Mon, 07 Sep 2026 00:00:00 +0000

NEC Corporation has ceased its research and development into superconducting quantum computers, shifting focus to quantum-inspired annealing and classical emulation due to long commercialization timelines and high capital investment. This move, reported by Nikkei Asia, means NEC will now concentrate on software and optimization services, leaving Fujitsu as the main domestic corporate developer of superconducting hardware in Japan. The post NEC Discontinues Superconducting Quantum Computer Development to Focus on Annealing and Classical Emulation appeared first on Quantum Computing Report .

Guest Post: QML4Africa Highlights Growth of Africa’s Quantum Research Community

Mon, 07 Sep 2026 00:00:00 +0000

Guest Post by Somtochukwu Igwegbe, African Quantum Consortium Correspondent, Research & Development, Quantum Africa. Quantum computing hardware is being built almost entirely outside Africa, in laboratories across North America, Europe, and Asia. That fact has shaped how the continent is usually written into the story: as a market to eventually reach, not a place doing the research. The second edition of the Quantum Machine Learning for Africa (QML4Africa) workshop, organized by Quantum Africa and held in August as part of Deep Learning Indaba 2026 in Lagos, Nigeria, was built around a different premise: that African researchers should be building with quantum tools now, while the field is still taking shape, rather than waiting to be introduced to it later. I attended the workshop as part of its organizing team, moving between sessions and conversations over the course of the day. From Kigali to Lagos QML4Africa began a year earlier in Kigali, Rwanda, as part of Deep Learning Indaba 2025. Organizers billed it at the time as the first QML workshop dedicated to the African continent , organized by Quantum Africa, with instruction led by researchers from IBM Research Africa and N

Three quantum phases in chromium-based material hint at a spin-triplet superconductor

Mon, 07 Sep 2026 00:00:00 +0000

Superconductors are materials that conduct electricity without electrical resistance when cooled below a specific critical temperature. These materials have proved promising for the development of various technologies, including medical imaging instruments, particle accelerators, ultrasensitive detectors and quantum processors.

Sparrow Quantum Sets Record With 500 Million Usable Photons Per Second

Mon, 07 Sep 2026 00:00:00 +0000

Insider Brief Sparrow Quantum and Ruhr University Bochum developed a deterministic source that delivers more than 500 million usable photons per second into optical fiber. The source operates at 1 gigahertz with more than 50% fiber efficiency while maintaining high photon purity and indistinguishability without spectral filtering. The increased photon supply could enable experiments involving 10 to 20 photons and support applications in quantum computing, networking, communications and metrology. PRESS RELEASE — Quantum computers are being built in several ways: superconducting circuits, trapped ions, neutral atoms, semiconductor spins and photonics. Photonic quantum systems have one fundamental advantage: their information carriers can travel through optical fibre, making the same technology relevant to both quantum processors and quantum networks. What photonic quantum systems need in exchange is a supply of photons that behaves: each one identical to the last, each arriving when the machine asks rather than when physics happens to oblige. For much of the field’s history, that has meant probabilistic sources: excite a material, wait for the photon-generation event to

NEC Halts Development of Quantum Computer Hardware

Sun, 06 Sep 2026 00:00:00 +0000

Insider Brief NEC has halted development of quantum computer hardware after determining that commercialization would take too long to produce an adequate return on investment. The company will continue developing quantum annealing, quantum-inspired computing and related services using conventional computer systems. The decision ends a hardware effort that included the world’s first demonstration of a superconducting solid-state qubit in 1999 and an eight-qubit annealing prototype unveiled in 2023. Image: NEC NEC has ended its effort to build a working quantum computer, pulling back from a field that the company helped pioneer. The company discontinued development of a physical quantum computing system at the end of March, Nikkei Asia reported . NEC apparently concluded that bringing the technology to market would take too long to produce an adequate return on its investment. NEC will continue working on related technologies and services, including quantum annealing — which is an approach designed to find efficient answers to problems involving a large number of possible combinations, such as optimizing delivery routes, production schedules or investment portfolios. The compan

Who’s News: Strategic Appointments at QuIC, Atom Computing, and Qilimanjaro Quantum Tech

Sat, 05 Sep 2026 00:00:00 +0000

Cécile Perrault is the new Executive Director of QuIC, Kevin Messerle is the new CFO of Atom Computing, and Albert Solana is the new Chief of Staff at Qilimanjaro Quantum Tech, all bringing their expertise to advance quantum technologies. The post Who’s News: Strategic Appointments at QuIC, Atom Computing, and Qilimanjaro Quantum Tech appeared first on Quantum Computing Report .

Brian Gaucher (ERVA): Why engineering, not physics, now limits quantum progress

Sat, 05 Sep 2026 00:00:00 +0000

Yuval Boger interviews Brian Gaucher, an experienced engineer and IBM veteran who co-chaired ERVA’s report Engineering Research to Advance Quantum Technologies. Brian explains that while U.S. quantum science remains strong, global competition is accelerating and the key limiter is no longer physics discovery but engineering the path from “lab to fab”—scalable, manufacturable, reliable systems. They discuss why the U.S. should pursue a coordinated, semiconductor-like national strategy with shared pilot lines, standards, metrology, public-private investment, and a broader workforce—not just physicists. They also cover the report’s four pillars (materials, biology, computing, AI), the importance of domestic fabrication, and why biology and quantum sensing may deliver surprisingly near-term impact. Transcript Yuval: Hello, Brian, and thank you for joining me today. Brian: My pleasure. Yuval: So Brian, who are you and what do you do? Brian: Oh, good question. It’s a long sordid story. I started off as an electrical engineer and hardware designer by background. And I spent probably 10 or 12 years at an aerospace and defense company doing military R&D for sat

Jülich Launches Trapped-Ion Quantum Computer For Supercomputing Integration

Fri, 04 Sep 2026 00:00:00 +0000

Insider Brief Forschungszentrum Jülich has inaugurated JION, a trapped-ion quantum computer intended to help researchers and companies test quantum computing alongside conventional supercomputers. Developed with eleQtron through a partnership receiving about 21 million euros in state funding, JION uses microwaves and magnetic fields to control charged ytterbium atoms. Two additional projects will each receive up to about 25 million euros to develop scalable trapped-ion technology and integrate a semiconductor quantum computer with up to 200 qubits into Jülich’s infrastructure. Official Launch of JION Quantum Computer at Jülich: Dr Michael Johanning, CTO of eleQtron, Jan Leisse, CEO of eleQtron, Minister-President Hendrik Wüst, Minister Ina Brandes, Prof. Dr Kristel Michielsen, Director of JSC, Prof. Dr Astrid Lambrecht, Chair of the Board of Directors of Forschungszentrum Jülich, and Prof. Dr Dr Thomas Lippert, Director of JSC. (Land NRW / Marius Becker) Germany’s Forschungszentrum Jülich has inaugurated a quantum computer intended to help researchers and companies test how quantum processors can work alongside conventional supercomputers. The system, called JION, is operational at

RIKEN Adopts QunaSys QURI SDK for Quantum-HPC Hybrid Computing

Fri, 04 Sep 2026 00:00:00 +0000

Insider Brief RIKEN has adopted QunaSys ’s QURI SDK Enterprise for the JHPC-quantum project, enabling users to access quantum computing resources from the Fugaku supercomputer environment. QURI SDK Enterprise supports IBM Quantum System Two and Quantinuum System Model H2, along with Fugaku and the ROQUO GPU supercomputer for quantum-HPC hybrid workflows. The SDK provides quantum-HPC algorithms including QSCI and ADAPT-QSCI, with applications spanning quantum chemistry, materials science and computer-aided engineering. PRESS RELEASE — QunaSys Inc. (headquartered in Bunkyo-ku, Tokyo; Representative Director and CEO: Tennin Yan; hereinafter “QunaSys”), a company specializing in the development of quantum computing algorithms and software, announced that its quantum software development kit “QURI SDK Enterprise” has been officially adopted for RIKEN ’s Quantum-HPC Hybrid Platform as part of the “JHPC-quantum” project. JHPC-quantum is a project commissioned by NEDO (New Energy and Industrial Technology Development Organization) under the jurisdiction of the Ministry of Economy, Trade and Industry (METI). The project has developed JHPC-quantum platform for quantum-HPC hybrid applic

Scientek and Classiq Partner to Accelerate Quantum Software Adoption in Taiwan

Fri, 04 Sep 2026 00:00:00 +0000

Insider Brief Scientek and Classiq have signed a go-to-market agreement to expand access to Classiq’s hardware-agnostic quantum software platform across Taiwan’s semiconductor, research and academic sectors. Scientek will introduce Classiq’s platform to companies, research institutes, universities and government organizations while supporting training, customer engagement and potential joint R&D programs. The partnership will initially target quantum applications in semiconductor research, materials and chemical simulation, optimization and hybrid quantum-classical computing. PRESS RELEASE – Scientek Corporation (科榮股份有限公司) and Classiq , the leading quantum computing software company, today announced a go-to-market agreement to expand access to Classiq’s hardware-agnostic quantum software platform across Taiwan’s semiconductor, research and academic communities. Under the partnership agreement, Scientek will introduce Classiq’s platform to semiconductor companies, research institutes, universities, government organizations and other customers within its established network. The companies also plan to offer enablement and training and explore joint r

Quantum Computing Challenges Holding Back Practical Quantum Computers

Fri, 04 Sep 2026 00:00:00 +0000

Insider Brief Quantum computing still faces major hardware, error correction, scaling, software and workforce challenges before it can support commercially valuable applications. High error rates and decoherence limit current quantum processors, while fault-tolerant systems require large numbers of physical qubits and significant advances in control, cooling, wiring and manufacturing. Limited quantum algorithms, immature software tools and a shortage of specialized workers add further constraints as the industry moves toward fault-tolerant quantum computing. Quantum computing has attracted billions in investment, sustained media attention, and some of the most concentrated scientific talent on a single engineering problem. Progress has been significant, but the results so far have yet to match the scale of investment and research behind the field. To date, no quantum computer has outperformed a classical computer on a commercially valuable problem. Current systems operate in what researchers call the Noisy Intermediate-Scale Quantum (NISQ) era, characterized by devices with enough qubits to demonstrate quantum behavior but too much noise to run useful algorithms reliably. The gap b

Quantum Foundry Copenhagen Plans 5,300-Square-Meter Chip Facility

Fri, 04 Sep 2026 00:00:00 +0000

Insider Brief Quantum Foundry Copenhagen plans to open a 5,300-square-meter quantum chip fabrication facility in Copenhagen in 2027 to support commercial-scale manufacturing. The facility will combine nanofabrication, characterization, testing, chip assembly, packaging and ultra-high-vacuum manufacturing capabilities. The Novo Nordisk Foundation has committed more than DKK 2.9 billion (€390 million) to quantum technologies, including a program targeting a fault-tolerant quantum computer before 2034. PRESS RELEASE — Today, Quantum Foundry Copenhagen and the Novo Nordisk Foundation announce plans to establish a new 5,300 m² quantum chip fabrication facility in Copenhagen. The facility will develop and scale the advanced manufacturing equipment needed to produce the next generation of quantum chips and strengthen Europe’s position in an increasingly competitive global quantum landscape. While Europe has built one of the world’s strongest research environments in quantum science, global leadership in quantum technologies will ultimately depend not only on scientific breakthroughs, but also on the ability to turn these breakthroughs into commercial products at scale. The fabricati

Forschungszentrum Jülich Operates eleQtron’s JION Trapped-Ion QPU via JUNIQ Infrastructure

Fri, 04 Sep 2026 00:00:00 +0000

Research center Forschungszentrum Jülich and University of Siegen spin-off eleQtron GmbH have officially brought the JION (Jülich trapped-ION) quantum computer into operation at the Jülich Supercomputing Centre (JSC). Integrated into the JUNIQ (Jülich UNified Infrastructure for Quantum computing) platform, the gate-based trapped-ion processor is linked directly to JSC's High-Performance Computing (HPC) supercomputing cluster—including the JUPITER [...] The post Forschungszentrum Jülich Operates eleQtron’s JION Trapped-Ion QPU via JUNIQ Infrastructure appeared first on Quantum Computing Report .

Quantum Foundry Copenhagen and Novo Nordisk Foundation Announce 5,300 m² Fabrication Facility for Quantum Chips

Fri, 04 Sep 2026 00:00:00 +0000

Technology firm Quantum Foundry Copenhagen and the Novo Nordisk Foundation have announced plans to construct a 5,300 m² commercial quantum chip fabrication facility in Copenhagen, Denmark. Operational by 2027, the infrastructure is engineered to bridge academic research with industrial manufacturing, offering commercial wafer fabrication, characterization, assembly, and packaging services to global quantum technology vendors. [ [...] The post Quantum Foundry Copenhagen and Novo Nordisk Foundation Announce 5,300 m² Fabrication Facility for Quantum Chips appeared first on Quantum Computing Report .

RIKEN Integrates QunaSys QURI SDK Enterprise into Japan’s JHPC-quantum Platform

Fri, 04 Sep 2026 00:00:00 +0000

The RIKEN Center for Computational Science (R-CCS) has officially adopted the enterprise quantum software development kit QURI SDK Enterprise from Tokyo-based algorithm developer QunaSys Inc. as the primary software layer for Japan’s national JHPC-quantum project. Funded by the New Energy and Industrial Technology Development Organization (NEDO) under the Ministry of Economy, Trade and Industry (METI), [...] The post RIKEN Integrates QunaSys QURI SDK Enterprise into Japan’s JHPC-quantum Platform appeared first on Quantum Computing Report .

MIT Qubit Design Could Speed Quantum Operations While Preserving Data

Fri, 04 Sep 2026 00:00:00 +0000

Insider Brief MIT researchers designed a qubit architecture that simulations suggest could speed quantum operations while preserving stored information, potentially supporting more reliable quantum computers. The “arm qubit” separates information storage from interactions with other components, using a specialized coupler to connect the two functions while reducing unwanted interference. The researchers plan to fabricate the qubit to test whether its predicted performance holds up in hardware and could support quantum error correction. MIT researchers have designed a quantum computing component that simulations suggest could perform faster operations while preserving stored information. It’s an advance that potentially could help future machines complete longer, more reliable calculations, according to the researchers. The architecture separates two jobs within a quantum bit, or qubit. One component stores information, while another connects with other qubits and electronics. According to MIT News , the design could address a central engineering challenge in quantum computing — allowing qubits to interact strongly enough to perform calculations without quickly losing th

Magic-angle graphene provides evidence for unconventional superconductivity

Fri, 04 Sep 2026 00:00:00 +0000

Researchers have completely suppressed superconductivity in magic-angle graphene by screening interactions between electrons, helping resolve a long-running debate about the origin of the phenomenon.

Europe Looks to Quantum Act to Turn Research Strength Into Industry

Fri, 04 Sep 2026 00:00:00 +0000

Insider Brief European quantum leaders called for coordinated action to turn the region’s scientific expertise into industrial capacity, competitive companies and strategic strength. The proposed EU Quantum Act is expected to promote cooperation, market consolidation, supply-chain resilience and links with sectors such as semiconductors, photonics and cloud computing. Speakers identified fragmented investment, limited coordination and competition for skilled workers as major obstacles to building a unified European quantum market. PRESS RELEASE — Europe’s quantum community gathered yesterday at the European Parliament for “ Europe’s Quantum Moment: From Lab to Leadership”, an event hosted by MEP Dr. Sergey Lagodinskythat brought together representatives from the European Commission, European Council and European Parliament, as well as quantum researchers, business leaders and investors. The goal of this high-level discussion was to explore how the EU could transform its indisputable scientific expertise into lasting industrial and strategic strength. But the discussion, organized into two panels, quickly developed into a thrilling debate on the geopolitical and economic chall

QuFi Launches Post-Quantum Verification Platform for Digital Assets

Fri, 04 Sep 2026 00:00:00 +0000

Insider Brief QuFi Network has launched the QuFi Platform, a post-quantum verification layer designed to validate digital assets and financial transactions without requiring changes to existing settlement networks. The platform uses a hybrid architecture combining ML-DSA-65, SLH-DSA and ML-KEM-1024 for post-quantum signatures and key encapsulation. QuFi has also introduced uBTC as a proof-of-concept on Bitcoin Testnet4 and opened applications for its Genesis Node Program to expand decentralized verification capacity. PRESS RELEASE — As the digital asset industry transitions toward post-quantum security, blockchain networks face an emerging infrastructure challenge. Depending on the cryptographic scheme and implementation, post-quantum signatures can be more than 100 times larger than the elliptic-curve signatures widely used today. This can drive substantial increases in storage, bandwidth, and computational requirements. As a result, every blockchain that adopts these new cryptographic standards must absorb those costs independently, creating scalability and efficiency constraints that compound across the broader digital asset ecosystem. QuFi Network Limited (“QuFi”) today a

Quantinuum and Aramco Execute Non-Binding MoU for Energy Sector Quantum R&D

Fri, 04 Sep 2026 00:00:00 +0000

Trapped-ion quantum hardware developer Quantinuum (NASDAQ: QNT) and integrated energy firm Aramco have executed a non-binding Memorandum of Understanding (MoU) during the LEAP technology conference in Riyadh. The agreement establishes a framework for preliminary technical onboarding, knowledge exchange, and benchmarking quantum modalities to identify industrial use cases across energy production and digital transformation workflows. [ [...] The post Quantinuum and Aramco Execute Non-Binding MoU for Energy Sector Quantum R&D appeared first on Quantum Computing Report .

Gate-level quantum simulation of nonunitary linear dynamics with hybrid oscillator–qubit architecture

Fri, 04 Sep 2026 00:00:00 +0000

Abstract We translate the one-mode unitary-dilation framework for nonunitary linear dynamics into a gate-level hybrid oscillator--qubit architecture. An ancillary oscillator encodes the integral kernel through state preparation and postselection. A qubit register represents and simulates the discretized system operator. The construction applies to time-independent dynamics $\dot u=-(L+iH)u$, including discretized partial differential equations, and removes the $\mathcal{O}(\log M_a)$ ancilla-qubit overhead of a discrete-variable (DV) $M_a$-term quadrature register. We bound the squeezed-Fock coefficient-projection error of the ideal kernel state. It decays superalgebraically with cutoff $N$ for Schwartz-class kernels and at a stretched-exponential rate under stronger joint decay and smoothness assumptions. The finite squeezed-Fock kernel state generically has stellar rank $N-1$, making $N$ a discrete measure of the oracle's non-Gaussian resource. For hybrid oscillator--qubit evolution, a $p$th-order product formula requires $\mathcal{O}(t^{1+1/p}N_{\mathrm{Fock}}^{(p+1)/(2p)}\epsilon_t^{-1/p})$ Trotter steps in the worst case, up to generator-dependent commutator fa

Spin qubit tuning automation for computer scientists

Fri, 04 Sep 2026 00:00:00 +0000

Abstract Tuning gate-defined quantum dots for qubit operation is an often frustrating and time-consuming activity in spin qubit research due to inherent device variability and the complex interactions between dots. Furthermore, tuning these devices grows more complicated as quantum computers grow to utility-scale. Computer-automated and machine learning techniques are popular approaches to accelerate the tuning process. However, these techniques need to become much faster and more accurate to address the tuning of millions of qubits in utility-scale quantum computing. We examine the literature of computer-automated and machine learning spin qubit tuning algorithms, grouping the algorithms by similar tasks and analyzing them from a computer science perspective to keep necessary background knowledge of quantum computing/physics at a minimum. We look at which approaches seem propitious for scaling up to utility-scale systems and where computer scientists could potentially have the most impact.

Efficient multi-controlled gate implementation in trapped-ion systems

Fri, 04 Sep 2026 00:00:00 +0000

Abstract Multi-controlled gates are essential primitives in quantum algorithms, yet implementing them via standard gate-level decompositions remains resource-intensive. We develop efficient pulse-level implementations of multi-controlled gates in trapped-ion systems using the Cirac–Zoller scheme. We first show that the Cirac–Zoller construction admits a freedom in the sign choice of red-sideband (RSB) pulses, which leaves the logical operation invariant up to a local Pauli-Z correction. By exploiting this freedom, we construct equivalent realizations of multi-controlled gates and develop pulse cancellation for more efficient implementations of successive gates. We perform numerical simulations and show that pulse cancellation reduces the gate time and improves the state fidelity. Furthermore, we propose ancilla-free circuits for general N-controlled gates that use a single-controlled gate primitive and O(N) RSB pulses. As a key application, we apply our pulse cancellation to the linear combination of unitaries (LCU) method for block encoding. We show that the RSB-pulse cost of the select operator over L unitaries can be reduced from O(L log L) to O(L), which improves the efficiency

Gravitational time dilation in quantum clock interferometry with entangled multi-photon states and quantum memories

Fri, 04 Sep 2026 00:00:00 +0000

Abstract Gravitational time dilation implies that clocks held at different heights accumulate different proper times. We analyze a memory-assisted photonic clock interferometer in which a two-frequency (frequency-bin) optical clock is stored in two vertically separated quantum memories for a controllable duration, such that the joint state evolves in a quantum superposition of two proper times. After retrieval, the photonic modes interfere in a Hong–Ou–Mandel (HOM) interferometer, for which we derive analytic expressions for the resulting multiphoton detection statistics. Extending this HOM-based scheme from entangled photon pairs to frequency-entangled 2N-photon inputs, we show that the proper-time dependent phase is amplified by a factor N, leading to an N-times faster collapse and revival of the interference signal compared with the two-photon case. Incorporating finite memory efficiency and lifetime, we identify regimes where this modulation remains observable. For parameters compatible with demonstrated Rb and Cs memories and achievable optical frequency separations, the first collapse occurs for height differences in the order of 10–100 m with subsecond to few-second storage

Split-post re-entrant microwave displacement transducer with quadratic readout

Fri, 04 Sep 2026 00:00:00 +0000

Abstract We investigate a microwave-cavity-based displacement readout employing a split-post geometry to measure the motion of a dielectric membrane. Due to symmetry, the cavity response to membrane displacement is inherently quadratic when the membrane is positioned at the centre of the posts. We characterise this behaviour by driving the membrane with a piezoelectric actuator at both central and off-centre positions and we estimate the drive-to-displacement transfer function using the independently calibrated frequency-to-voltage response of the interferometric readout. When the membrane is located at the centre of the cavity and driven, the system exhibits the largest quadratic output, measured at the second harmonic of the membrane acoustic frequency. As the membrane is moved away from the centre, the response transitions from predominantly quadratic to predominantly a linear response at the membrane acoustic frequency. Quadratic optomechanical coupling is a key requirement for displacement - squared readout and, in the quantum regime, for measurements sensitive to mechanical energy or phonon number. The present work therefore establishes the split-post geometry as a promising

Towards Scaling Quantum Fine-Tuning of Foundational Time Series Models for Classification

Fri, 04 Sep 2026 00:00:00 +0000

Time-series foundation models produce rich embeddings, but whether quantum models can exploit them, and how far hybrid classical-quantum architectures scale, remains unclear. We address this by fine-tuning Chronos for power-grid event classification (PSML-5) with a quantum head on the model's embeddings. Grouping embeddings by physical sensor type before summarization already surpasses the best published baseline built for this benchmark, and with finer-grained features the quantum head outperforms a larger classical multilayer perceptron on identical inputs by 1.7-2.0 percentage points of balanced accuracy. Yet the gains saturate: past a point, feeding more information to the same fixed-width register yields no improvement. We show the bottleneck is neither the supply of information nor circuit expressiveness, but the bandwidth of the data intake. To overcome this limitation, we introduce the wing module, a self-contained few-qubit circuit that feeds additional information into the core circuit through a sparse, one-way coupling. Under a preregistered four-seed protocol, we attach wings to a fixed 12-qubit core with fixed features. Balanced accuracy increases with each added wing,

Parametric and feedback-controlled multiparameter quantum estimation in a double cavity optomechanics: steady and dynamical state

Fri, 04 Sep 2026 00:00:00 +0000

Multiparameter quantum estimation in open optomechanical systems is fundamentally constrained by dissipation, thermal fluctuations, and measurement incompatibility. In this work, we investigate a coupled-cavity optomechanical platform in which two mechanical modes interact with driven optical cavities, two-mode squeezed vacuum, intracavity degenerate parametric amplification, and coherent optical feedback. Using the continuous-variable Gaussian-state formalism, we derive the linearized quantum Langevin dynamics and steady-state covariance matrix and evaluate the quantum Fisher information matrices associated with simultaneous estimation of the optomechanical coupling strength and cavity dissipation rate. We characterize the precision bounds using the symmetric and right logarithmic derivative formalisms and employ $\mathcal{B}_{\rm MI}=\max\{\mathcal{B}_S,\mathcal{B}_R\}$ as a comparative figure of merit within the SLD/RLD framework. We find that parametric amplification can substantially reduce , demonstrating an enhancement of multiparameter sensitivity over a broad range of operating conditions. In contrast, coherent feedback produces a nonmonotonic modification of the estimatio

Non-reciprocally interacting Ornstein-Uhlenbeck processes: Exceptional points, Anomalous relaxation, Pseudo-equilibrium and Boundary refrigeration

Fri, 04 Sep 2026 00:00:00 +0000

Non-reciprocal interactions are ubiquitous in active, biological, and disordered systems, generically driving them out of equilibrium. Here, we introduce a hierarchy of non-reciprocally interacting Ornstein-Uhlenbeck (NROU) models governed by a tunable non-reciprocity parameter $g$. At a special point $g=g^*$, the drift matrix becomes non-diagonalizable, realizing exceptional points (EP's) of different orders, where eigenvalues and eigenvectors simultaneously coalesce. The hierarchy encompasses non-reciprocally coupled dimers, their disordered counterparts, and a many-body chain exactly mapping onto the paradigmatic Hatano-Nelson model in the arena of non-Hermitian quantum systems. For the disordered model, we show that the distribution of the EP location $g^*$ across disorder realizations develops a universal edge singularity precisely at the clean-system EP, and is manifestly non-self-averaging. Across all models, we find that at the EP, the usual exponential relaxation of the autocorrelation and covariance functions is dressed by a polynomial-in-time prefactor whose degree is set by the order of the EP and whose detailed structure encodes the spatial architecture of the chain. A

A photonic source with half-a-GHz single-photon flux

Fri, 04 Sep 2026 00:00:00 +0000

Advanced optical quantum technologies demands high quality quantum light generation at very high rates. Here, we report on a deterministic single-photon source that simultaneously combines high excitation rates with high system efficiency to reach over 500 MHz of in-fibre single-photon flux. The source delivers optical power of over 100 pW, as is measured with an off-the-shelf powermeter, enabling a simple and direct way of determining the single-photon source fiber efficiency.

Coincidence-based spectral engineering for spectral matching in cascaded downconversion

Fri, 04 Sep 2026 00:00:00 +0000

Three-photon states generated via cascaded spontaneous parametric downconversion provide a direct route to multipartite entanglement. However, current implementations require careful spectral matching between successive nonlinear stages, which constrains the choice of downconversion sources. In this work, we show that coincidence-based spectral filtering relaxes this requirement by conditionally tailoring the spectrum of the pump photon entering the second stage. By filtering the herald photon, we conditionally tailor the spectrum of its partner to match the acceptance bandwidth of the secondary nonlinear process, enabling efficient coupling between broadband and narrowband stages without altering the sources themselves. Using an electro-optically gated spectrometer, we directly measure the conditional spectra that govern the cascaded process, allowing us to quantitatively predict the enhancement in second-stage conversion probability per detected herald. We then verify this prediction through photon-triplet measurements, demonstrating improved performance at fixed heralding rates. Our results establish coincidence-based spectral engineering as a practical tool for optimizing casca

Fundamental Limits of Quantum Metrology Beyond Fixed Causal Order

Fri, 04 Sep 2026 00:00:00 +0000

Quantum metrology with indefinite causal order (ICO) has attracted intense interest due to its potential to surpass the limitations of conventional fixed-order strategies. A key open question is whether ICO can fundamentally enhance asymptotic precision scaling. In this work, we bridge this gap for the estimation of a single parameter encoded in $N$ identical uses of a finite-dimensional quantum channel. We first establish a universal Heisenberg-scaling upper bound for the full general ICO process-matrix class and show that for unitary channels its optimal quantum Fisher information (QFI) coincides exactly with that of parallel strategies. For noisy channels, a structurally refined bound shows that channels restricted to the standard quantum limit (SQL) under parallel strategies remain SQL-limited under general ICO strategies. Most significantly, an asymptotically tight (AT) bound is derived to close the remaining possibility of an asymptotic ICO advantage by showing that general ICO and optimal parallel strategies have exactly the same leading QFI coefficient in both the SQL and Heisenberg regimes. For the operationally motivated class of quantum circuits with quantum control of c

How dipolar interactions structure molecular droplets

Fri, 04 Sep 2026 00:00:00 +0000

We investigate how dipolar interactions between microwave-shielded polar molecules structure the self-bound droplets formed under variation of the interaction strength. We identify the transition from droplets to crystals as a finite-size first order transition. With droplet-ring states and transitional supersolid states we predict additional structure in the crystal and droplet phases, respectively. To describe this strongly correlated regime, and in particular the reconfiguration of quantum ground states, we design a variational Monte Carlo framework based on neural quantum states. It is especially suitable to describe ground states and almost degenerate states with very different configurations. Moreover, one can easily determine the superfluid fraction. Our results reveal the sequence of finite-size structures through which dipolar interactions reorganize molecular droplets into crystals.

Restricting the effects hides a nonphysical symmetry from every causal structure

Fri, 04 Sep 2026 00:00:00 +0000

Real-amplitude quantum theory is the subtheory of quantum theory invariant under complex conjugation, and experiments in a network of independent sources have measured correlations above the real bound. A theory can nevertheless carry the same conjugation without complete positivity and still have exactly the correlations of its own conjugation-invariant subtheory in every causal structure, the bilocality scenario included. The states of that theory are all the density matrices, and its effects are the operators every partial transpose of which is again a quantum effect. Its symmetrized subtheory simulates it once each source carries a reference frame rather than each system. One map therefore receives three different verdicts in three theories, so the symmetry alone marks no boundary at all, and what sustains the separation in quantum theory is a property of quantum theory. Quantum theory admits every effect its states permit and this theory does not. What does have a boundary is the class of theories where the correlations of a theory and of its symmetrized subtheory coincide. We show that sectorial closure, meaning invariance of the effects and the operations under the symmetry

Compiling the 2D Fermi-Hubbard ground-state energy estimation algorithm for active volume quantum architectures

Fri, 04 Sep 2026 00:00:00 +0000

As quantum computing enters the early fault-tolerant era, circuit compilation choices will increasingly depend on details of the underlying architecture rather than solely optimizing for generic proxies such as non-Clifford count. We present an active-volume-aware compilation of the ground-state energy estimation algorithm for the two-dimensional Fermi-Hubbard model using quantum phase estimation and Trotterized time evolution. The proposed compilation reduces the active volume across $L\times L$ square lattices with $L=4$ to $20$, achieving up to a $3.9\times$ reduction over prior work optimized for non-Clifford cost. As a by-product of these compilation improvements, the resulting circuits also achieve state-of-the-art Toffoli counts, with a ~$2\times$ reduction for the $L=20$ case. Lastly, the active volume architecture and recent execution scheduling advances provide a means of translating these reduction trends into runtime. This demonstrates the increasing importance of architecture-aware compilation for practical early fault-tolerant quantum computing.

SAR and InSAR Change Detection with Quantum Generative Models

Fri, 04 Sep 2026 00:00:00 +0000

Change detection in synthetic aperture radar (SAR) and interferometric synthetic aperture radar (InSAR) underpins disaster response, infrastructure monitoring and land-use enforcement. Detection is limited by the background estimator, which conventionally forms a conditional expectation directly from observed pixel statistics and degrades where those statistics are sparse, including the regime produced by the heavy-tailed marginals of sub-meter-resolution radars. In this work, we integrate state-of-the-art satellite imagery with quantum machine learning on IonQ trapped-ion-based quantum processors. By replacing the empirical conditional with a quantum circuit Born machine (QCBM)-sampled generative model in Copula space, we substantially improve change detection on sparse real-world images. On Capella Space satellite image acquisitions, the generative estimator matches conventional methods when the observed statistics are adequate, and substantially outperforms them when they are not. Executing the trained model on IonQ trapped-ion based hardware reproduces the results of the ideal and noisy simulations and demonstrates up to par, or even better, performance with the classical state

Memory-Optimal Sequential Synthesis of Multimode Gaussian Transformations

Fri, 04 Sep 2026 00:00:00 +0000

In modular quantum computing architectures, communication between hardware modules is mediated by traveling qumodes sent through transmission lines. Each output qumode interacts with the emitting module only once through a beam-splitter-type interaction and becomes inaccessible to that module after emission. Information required for subsequent outputs must therefore remain in long-lived memory qumodes. For a prescribed multimode Gaussian transformation on $N$ qumodes, this work determines the minimum memory cost for any given emission order, constructs an explicit sequential protocol attaining this minimum, and develops a greedy method for identifying memory-efficient emission orders. The transformation is represented by a symplectic matrix $S$, specified either directly or through a Gaussian gate sequence. The exact minimum memory cost is obtained from the ranks of submatrices of $S$ and further reduces to a support-based counting rule whose computational cost is linear in the size of the support data. When $S$ is specified directly, a matrix-based protocol attains the minimum memory cost. If instead $S$ is specified through a gate sequence, the original gates can be reused withou

Quantum-State Texture Dynamics: Theory and Experiment

Fri, 04 Sep 2026 00:00:00 +0000

Quantum-state texture (QST) has found applications in several fields from quantum foundations and computation to quantum criticality. However, a general theory of QST dynamics under arbitrary physical processes remains unavailable, limiting both its practical application and experimental exploration. Here, we demonstrate that the QST response to an arbitrary finite-dimensional channel is fully encoded in the dual evolution of a single reference state. This description yields necessary and sufficient conditions for texture preservation and implies exact conservation under all free-unital dynamics. Using a nuclear magnetic resonance quantum processor, we experimentally verify these predictions across distinct channel classes. Furthermore, we show that local QST measurements provide an operational signature of entangling gates in circuit layers. Our results establish quantum-state texture as a resource and a practical diagnostic tool in quantum information processing.

Quantum Optimisation for Protein-Protein Interaction Network Alignment

Fri, 04 Sep 2026 00:00:00 +0000

Protein-protein interaction (PPI) network alignment combines topological and sequence information to identify conserved modules across species, but global alignment remains challenging: heuristics sacrifice optimality, while exact methods lack scalability. We model the alignment as a weighted maximum common induced subgraph problem and reformulate it through the modular product graph to a minimum-weight vertex cover on the complement, with node weights carrying sequence similarity. To solve this problem, we develop a hybrid framework combining kernelisation, branch-and-bound, and seven Quantum Approximate Optimisation Algorithm (QAOA) formulations. These formulations differ in how the cover constraints are enforced, from penalty terms in the cost Hamiltonian to mixers confined to the feasible subspace. For single round QAOA, we derive closed-form expressions for the expected cost of four circulant mixer variants, enabling performance characterisation without circuit simulation. Applied to synthetic and real-world networks reduced to KEGG pathways, the QAOA formulations achieve high topological conservation on the aligned core while at least maintaining biological conservation compa

TETRIS-Q: Tiling-based Effective Transient-fault Reduction on Interleaved Superconducting Qubits

Fri, 04 Sep 2026 00:00:00 +0000

The struggle of the hour in quantum computing research is achieving effective suppression of the error mechanisms induced by the interaction of external radiation with superconducting quantum devices. Despite the rapid advancements in quantum error correction (QEC) of recent years, radiation-induced faults are yet to be fully addressed. These events are known to be the cause of simultaneous correlated defects in qubits that lie onto a single substrate, ultimately jeopardising QEC code effectiveness. In this paper, we propose to selectively combine substrate-level phonon barriers and QEC interleaving via a planar-mesh tiling algorithm, TETRIS-Q, reaching efficient and effective suppression of radiation events. Our cross-layer solution comes at no extra cost in terms of QEC code execution or decoding time. We model and simulate radiation-induced transient faults over a plethora of barrier and QEC interleaving configurations. Through more than 51 million quantum circuit simulations, we show peak logical error reductions of more than $99.8 \%$, together with an $80\%$ reduction of the observable transient duration with permeable barriers. We find that sparser tiling can reach comparabl

The marginal is pretty good

Fri, 04 Sep 2026 00:00:00 +0000

One-shot information theory measures often require an optimization over states, but the form of these optimizers can be complicated or depend on the initial problem in nonlinear ways. In this note, we show that in many instances using the marginal instead of the optimal state is sufficiently good and only changes the result by a small factor. We prove that for the Petz-Rényi divergence of order $α\in[1/2,1)$, replacing the optimizing state on $B$ by the marginal $ρ_B$ results in a multiplicative overhead of at most $1/α$. We also show a similar relation for the fidelity, and in the case of pure or quantum-classical states for the sandwiched Rényi divergence.

A double-resonator coupler for high-fidelity two-qubit gates between superconducting qubits

Fri, 04 Sep 2026 00:00:00 +0000

Tunable couplers have enabled two-qubit gate fidelities in superconducting quantum processors to approach $99.9\%$, yet simultaneously suppressing residual interactions and maintaining flexible qubit-frequency allocation remain central challenges for scaling. Here, we propose a double-resonator coupler (DRC) consisting of two resonators interconnected by a single Josephson junction and a capacitor. The hybridized resonator modes provide two mediated exchange paths whose interference controls the qubit-qubit interaction. The DRC enables complete cancellation of residual $ZZ$ interaction for qubit-qubit detunings well outside the straddling regime, even in the absence of direct qubit-qubit coupling, thereby relaxing constraints on frequency allocation and qubit placement. Away from the idle point, the same circuit provides a strong $ZZ$ interaction of approximately $70\,\mathrm{MHz}$, enabling a $20\,\mathrm{ns}$ controlled-Z gate with simulated coherent infidelity below $10^{-5}$. These results establish the DRC as a flexible single-junction coupler architecture for high-fidelity superconducting quantum processors.

Robustness of RKKY interactions across a Weyl node-annihilation transition

Fri, 04 Sep 2026 00:00:00 +0000

Weyl semimetals (WSMs), with their unique topological properties and distinct electronic structure, exhibit intriguing properties when either time-reversal or inversion symmetries are broken. In this work, we consider the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction between magnetic impurities in time-reversal symmetry-breaking WSMs. We derive analytical expressions for the full RKKY exchange tensor in arbitrary two-band spinful lattice systems. Our approach reveals both Heisenberg, anisotropic Ising and Dzyaloshinsky-Moriya terms, which can be calculated by energy-integrating real-space Green's functions across the entire Brillouin zone, with the band edge acting as a natural energy cutoff. We apply this framework to study a two-band tight-binding model for a time-reversal symmetry-breaking WSM that interpolates between a Weyl phase with well-separated chiral nodes and a quadratic band-touching semimetal phase. Remarkably, the spatial profile, magnitude, and anisotropic tensor structure of the exchange couplings remain persistent across the node-annihilation transition. This topological robustness reveals that short- and intermediate-range RKKY interactions are mediated by the

Optimal inequalities for completely bounded polynomials and the limitations of quantum query algorithms

Fri, 04 Sep 2026 00:00:00 +0000

We consider the problem of establishing limitations on the power of quantum query algorithms via the completely bounded polynomial method. In particular, we prove several optimal functional inequalities involving different notions of completely bounded polynomials. These inequalities lead to limiting theorems for the power of quantum query algorithms that improve on prior works. 1. An optimal root-influence bound for block-multilinear polynomials. Prior work showed that block-multilinear polynomials $p$ of degree $t$ satisfy a root-influence bound, $\|p\|_{\text{cb}}\geq \sum_i \sqrt{\mathrm{Inf}_i[p]}/t^2$, which is stronger than the bound appearing in the Aaronson-Ambainis conjecture. We find the optimal constant in that inequality: $\|p\|_{\text{cb}}\geq \sum_i \sqrt{\mathrm{Inf}_i[p]}/t$. Since the amplitudes of quantum algorithms that query disjoint blocks of inputs-such as $t$-fold forrelation- are block-multilinear polynomials with $\|p\|_{\text{cb}}\leq 1,$ our inequality shows that they satisfy $t\geq \sum_i\sqrt{\mathrm{Inf}_i[p]}$. We prove that this inequality yields both a more efficient classical simulation than prior results based on the Aaronson-Ambainis argument, a

Dynamical Reduction of Two Series Josephson Junctions to a Synthetic High-Transparency Josephson Element

Fri, 04 Sep 2026 00:00:00 +0000

Two conventional Josephson junctions connected in series can reproduce, in the static limit in which the currents through the capacitive and resistive channels are negligible, the current-phase relation of a single effective weak link with tunable transparency. Therefore, the two-junction series can be treated as a single synthetic high-transparency element. Here, we investigate to what extent this mapping remains valid under finite-frequency drive and retaining the junctions' resistive and capacitive terms. The full resistively and capacitively shunted junction equations are compared with an effective synthetic element with tunable transparency that retains the synthetic tunable-transparency current-phase relation together with effective capacitive and dissipative terms, thus reducing the two second order degree of freedom system to a single second order degree of freedom. The resulting single-element dynamics is compared with the complete two-junction system under ac excitation. The agreement is quantified through a normalized root-mean-square error between the full and effective voltage waveforms. A broad low-error region is found at low drive frequency, while pronounced deviati

Electrostatic splitting of an Edge Magnetoplasmon Resonator

Fri, 04 Sep 2026 00:00:00 +0000

Edge-magnetoplasmon resonators have been proposed as a powerful tool to detect anyons by introducing a quantum point contact into an isolated quantum Hall system probed via radiofrequency radiation. In this paper, we study the effect of a quantum point contact embedded within an edge-magnetoplasmon resonator and how its polarization influences the propagating magnetoplasmonic mode. Combining dc and rf measurements, we unambiguously evidence the signature of both integer ($ν= 1$ and $2$) and fractional quantum Hall states ($ν= 4/3$ and $2/3$) within the radiofrequency transmission signal. Using electrostatic gating, we determine the physical parameters characterizing the electrostatic edge of an AlGaAs/GaAs based two-dimensional electron gas. We extract the dependence of the cavity perimeter with the gate voltage of the quantum point contact and fully characterize the path followed by edge magnetoplasmons in this system. Finally, we provide a geometric model in good agreement with experimental results.

AxQM: A Textbook-Scale Benchmark for Formal Proof Synthesis in a Library of Finite-Dimensional Quantum Mechanics

Fri, 04 Sep 2026 00:00:00 +0000

Formalizing mathematics in a proof assistant, where a machine checks every definition, statement and proof, has set a new standard of rigor. Large language models are now capable of formalizing autonomously, even at the scale of whole textbooks. We bring this standard of rigor to physics, where theoretical arguments carry idealizations that are rarely stated fully, and any logical gaps could have a cascading effect on interdependent results. Recognizing the need to evaluate autoformalization systems for physics, we release AxQM, 1,019 kernel-checkable proof-synthesis tasks over 479 items drawn from the textbook Quantum Computation and Quantum Information by Nielsen and Chuang. The tasks are stated in a custom Lean library of finite-dimensional quantum mechanics. By task count, it is the largest proof-synthesis benchmark in physics by a factor of four. AxQM is derived from a near-complete formalization of the formal portions of the textbook, so every task is guaranteed a solution, which we keep private. Grading of the benchmark is done deterministically by the Lean kernel, which checks that the proof compiles, that no sorry appears in it or in any declaration it depends on, and that

Fanout Complexity of Symmetric Boolean Functions in $\mathsf{QAC}^0$

Fri, 04 Sep 2026 00:00:00 +0000

Whether $\mathsf{QAC}^0$ can compute $\mathtt{PARITY}_n$ remains open. Computing $\mathtt{PARITY}_n$ is equivalent to implementing $\mathtt{FANOUT}_n$ under $\mathsf{QAC}^0$ reductions. This raises a more general question: for an arbitrary symmetric Boolean function $f:\{0,1\}^n\to\{0,1\}$, what fanout size is necessary and sufficient for computing $f$ in $\mathsf{QAC}^0$? We show that the answer is exactly the transition radius $ρ(f)$: computing $f$ and implementing $\mathtt{FANOUT}_{ρ(f)}$ are equivalent under $\mathsf{QAC}^0$ reductions. In particular, if $ρ(f)\ge n^δ$ for some constant $δ>0$, then computing $f$ is $\mathsf{QAC}^0_{\mathrm{f}}$-complete. Combined with Paturi's theorem, our characterization implies that if $\mathtt{PARITY}_n \notin \mathsf{QAC}^0$, then any Boolean function in $\mathsf{QAC}^0$ of approximate degree $n^{1/2+Ω(1)}$ must be nonsymmetric.

Environment-assisted transport in a strongly correlated boundary-driven Fermi-Hubbard chain

Fri, 04 Sep 2026 00:00:00 +0000

We study steady-state transport in a one-dimensional Fermi-Hubbard chain coupled to particle reservoirs at the boundaries and to local dephasing baths at each site, using the time-evolving block decimation (TEBD) method to solve the Lindblad master equation. In the absence of dephasing, the current exhibits two well-separated maxima as a function of the boundary driving rate, reflecting the distinct charge and spin energy scales of the strongly correlated regime. Upon introducing dephasing, we find two distinct dephasing-induced transport-enhancement regimes, in contrast to the single enhancement previously reported for spinless fermions. Analysis of the non-equilibrium steady state in the Hamiltonian eigenbasis reveals that the two regimes originate from distinct dephasing-induced redistribution processes: the first involves redistribution within the uppermost Hubbard band, while the second involves transitions between Hubbard bands. Our results demonstrate how many-body correlations shape the interplay between coherent driving, dephasing, and quantum Zeno physics in strongly correlated open systems.

Non-local games and communication complexity with noisy entanglement

Fri, 04 Sep 2026 00:00:00 +0000

We study the impact of noise on the theories of quantum nonlocality and entanglement-assisted communication complexity. We consider non-local games and entanglement-assisted communication complexity in a model where Alice and Bob may share arbitrarily many noisy EPR pairs. We study four noise models: depolarizing noise, unital noise, biased reset noise, and erasure noise. Our results are as follows: 1. We upper bound the value of the CHSH game under all these noise models in terms of the noise parameter, without any assumptions on the measurements used in the strategy. 2. We prove a parallel repetition theorem for general non-local games under all noise models except biased reset noise; we prove an improved parallel repetition theorem for unique games. Our parallel repetition rate is smaller than the quantum parallel repetition rate for CHSH in a nontrivial noise regime. 3. Using our unique-game parallel repetition theorem and a relation defined by the CHSH game, we prove a separation between communication complexity with noisy vs noiseless entanglement. This implies an $Ω(n)$ two-way communication lower bound for distilling $n$ EPR pairs from noisy EPR pairs, in the same nontrivia

On the growth of operator entanglement in brickwork circuits with Yang--Baxter gates

Fri, 04 Sep 2026 00:00:00 +0000

We study the operator entanglement of local operators in one-dimensional brickwork circuits whose two-site gate satisfies the braid relation; throughout this work, we call such a gate a Yang--Baxter gate. We establish upper bounds for several structured, overlapping classes of Yang--Baxter gates. We show that the operator Schmidt rank remains uniformly bounded in time for all qubit Yang--Baxter gates and, in arbitrary local dimension, for permutation gates obtained from non-degenerate Yang--Baxter maps. We also show that it grows at most polynomially for involutive dual-unitary Yang--Baxter gates and for arbitrary phase dressings of permutation gates obtained from non-degenerate Yang--Baxter maps. These results imply, respectively, constant and logarithmic upper bounds on the operator entanglement. Conversely, we construct a seven-state involutive Yang--Baxter gate without dual unitarity and a one-site operator whose exact operator Schmidt rank grows exponentially, although the corresponding operator entropies remain undetermined. Entanglement growth in the general Yang--Baxter case remains open. All proofs and selected examples were constructed by ChatGPT 5.6 Sol.

Operational Roles of QRNG-Derived Quantum Entropy in Bitcoin Proof-of-Work Architectures

Fri, 04 Sep 2026 00:00:00 +0000

Replacing classical entropy with QRNG output does not change honest Bitcoin PoW success probability when candidate headers remain distinct. The original contribution of this paper is a reproducible benchmark that locates and measures the operational value of quantum entropy in hybrid quantum-classical mining infrastructure through two scheduler-level observables, the entropy-efficiency factor $η$ and the reboot-diversity index $ρ$. Monte Carlo and scheduler simulations with confidence intervals show parity for competent deterministic and strong-classical baselines, while QRNG value emerges in assurance-oriented scenarios involving correlated restart faults, namespace reuse, and entropy provenance. The study is therefore positioned as a simulation-based validation framework rather than as a device-level QRNG demonstration; hardware-in-the-loop validation with recorded or live QRNG streams is identified as the next experimental step.

Engineering Giant Thermoelectric Performance through Electrode-Coupling Geometry and Magnetic Flux in Quasiperiodic Su-Schrieffer-Heeger Rings

Fri, 04 Sep 2026 00:00:00 +0000

We investigate coherent thermoelectric transport in magnetic-flux-threaded quasiperiodic Su-Schrieffer-Heeger (SSH) rings with engineered multi-site electrode couplings using the nonequilibrium Green's function formalism within the Landauer-Büttiker framework. We demonstrate that the electrode-coupling geometry serves as a powerful control parameter for tailoring quantum interference, thereby reshaping the transmission spectrum and thermoelectric response. In the absence of magnetic flux, the trivial dimerized phase ($t_1>t_2$) exhibits the highest thermoelectric efficiency, with asymmetric coupling producing a substantially larger figure of merit than the symmetric geometry. Magnetic flux further reconstructs the transmission spectrum through Aharonov-Bohm interference, driving a crossover of the optimal thermoelectric regime from the trivial to the topological dimerized phase. Under optimal flux conditions, the thermoelectric figure of merit reaches $ZT \approx 12$ for symmetric coupling and is dramatically enhanced to $ZT \approx 90$ for asymmetric coupling through enhanced energy filtering and suppressed electronic thermal transport. We further establish a clear correlation bet

Impact of Data Loss in Postprocessing on Training and Inference of Quantum Neural Networks

Fri, 04 Sep 2026 00:00:00 +0000

As quantum hardware scales to larger devices, the classical software layers that interface with it must evolve in step. Postprocessing routines developed and tested primarily in simulator settings can encode assumptions that no longer hold on utility-scale devices, leading to data loss that can be difficult to detect from high-level model outputs alone. We present a case study of \texttt{SamplerQNN}, the sampling-based quantum neural network class in the Qiskit Machine Learning library. Here, the postprocessing method applies a filter that assumes measurement bit-strings are in virtual qubit space. On our quantum hardware runs, where bit-strings span over 100 physical qubits, this filter led to the loss of 85 to 99.6\% of valid measurement shots, depending on the transpiler's qubit placement. The resulting probability vector is unnormalised, allowing distorted prediction and loss values to propagate through the model without an API-level warning. We demonstrate the impact across five experiments on two IBM backends: for inference, accuracy drops from 0.94 to 0.39 on the same raw measurements; for training, the loss signal is compressed by 22 to 27$\times$, substantially reducing th

Qlippy: A Retrieval-Augmented GenAI Assistant for Reproducible Quantum Workflows and Experiment Tracking

Fri, 04 Sep 2026 00:00:00 +0000

Quantum software development is iterative and error-prone. Noisy hardware and repeated re-execution make experiment tracking, provenance, and reproducibility essential, yet these practices are hard to adopt because of tooling complexity and the specialized knowledge they demand. General-purpose language models can help but tend to hallucinate and lack grounding in domain-specific tooling. We present Qlippy, a retrieval-augmented GenAI assistant embedded in the development environment that grounds its responses in a curated corpus of quantum-software-engineering knowledge. Qlippy explains reproducibility and provenance concepts in context and augments existing Qiskit programs with MLflow-based experiment tracking aligned to the QProv schema. By separating knowledge from model parameters, grounding gives explicit control over the scope and provenance of the assistant's responses and reduces reliance on model scale, which points toward low-cost, privacy-preserving local deployment.

Hadamard Rigidity of Positive Sojourn Time Distributions for Rotation Coins

Fri, 04 Sep 2026 00:00:00 +0000

We study the distribution of the positive sojourn time for a one-dimensional two state quantum walk, conditioned on return to the origin. Konno showed that, for the Hadamard walk, this conditional distribution is exactly uniform at times divisible by $4$. In this paper, we investigate whether this finite time exact uniformity characterizes the Hadamard coin within the family of rotation coins. For a fixed initial state, we prove that the following three conditions are equivalent for rotation coins: the conditional distribution is exactly uniform at time $8$; the conditional distribution is exactly uniform at every time $4m$ with $m\ge2$; and the coin is the Hadamard coin. Thus, the uniformity phenomenon found by Konno is characterized as a rigidity phenomenon of the Hadamard coin within the rotation coin family. The proof uses a matrix-valued generating function for paths returning to the origin. We analyze the algebraic structure arising from an absorbing process on the half line. Finally, by comparing low degree coefficients at time $8$, we show that exact uniformity forces the rotation coin to be the Hadamard coin.

ANT:UI: An interactive 3D tool for preparing ANT.Gaussian molecular junction geometries

Fri, 04 Sep 2026 00:00:00 +0000

ANT.UI is a Python graphical interface that automates the construction of molecular-junction geometries for NEGF-DFT quantum transport calculations. Through a real-time 3D viewer, users interactively position electrodes and molecules and generate complete, ready-to-run input files for Gaussian and ANT.Gaussian without manual scripting. Dedicated Pull, Grid, and Rotation assistants further automate electrode-pulling sequences, surface scans, and step-wise rotation studies, with optional geometry-optimisation chaining across each sequence. By replacing a process that previously demanded days of custom scripting with a point-and-click workflow, ANT.UI accelerates research in theoretical molecular electronics and lowers the barrier to entry for new users. The software also exports all constructed geometries in standard XYZ format, allowing direct reuse in molecular dynamics codes or third-party visualization tools without manual reformatting.

Lindblad Multiproduct Formulas

Fri, 04 Sep 2026 00:00:00 +0000

We introduce Lindblad Multiproduct Formulas: a quantum error mitigation technique that uses two-dimensional tensor networks contracted with loop-corrected belief propagation. The quantities required to implement the error mitigation scheme that are evaluated with tensor networks can be less computationally expensive to calculate than the expectation values themselves, thus allowing for the possibility of applying our method to certain systems for which tensor network methods may struggle to calculate the observable quantities of interest. The workflow incorporates Clifford rescaling techniques and outputs an estimated error bar. We apply our method to a model of two-dimensional discrete time crystals studied previously and implement it on $65$ qubits arranged in a $3\!\times\!3$ heavy-hexagonal topology on the quantum computer ibm_basquecountry. We show that a GPU implementation of the classical part of our workflow achieves a speedup of up to $5.6\times$.

Learning unknown stabilizer codes using product measurements

Fri, 04 Sep 2026 00:00:00 +0000

Efficiently characterizing quantum error correcting codes is a key challenge on the path to fault-tolerant quantum computation. Stabilizer codes, a central class of such codes, are defined by a set of stabilizer generators. Here, we present an algorithm that uses random single-qubit measurements to learn the stabilizer generators of any stabilizer code from $N$ copies of stabilizer states in its codespace, requiring no prior knowledge of the code's structure. This also enables verification that a device implements its intended code. We derive a lower bound on $N$ needed to recover the stabilizer generators with high probability, together with a bound on the algorithm's overall probability of success. When applied to quantum low-density parity-check (qLDPC) codes, a leading candidate for practical fault-tolerant architectures, our approach requires a number of states that scales polylogarithmically with $n$, the number of qubits.

From the Light Quantum to the Photon: The Evolution of a Physical Concept

Fri, 04 Sep 2026 00:00:00 +0000

This work examines the physical and conceptual evolution of the light quantum from Planck's blackbody theory to the theoretical and experimental developments that led to the quantization of the electromagnetic field. The present study shows that the decisive transition occurred in Einstein's quantum theory of radiation (1916-1917). Absorption, stimulated emission, and spontaneous emission were formulated as elementary probabilistic mechanisms whose statistical balance alone reproduces the blackbody spectrum. In particular, spontaneous emission requires the emission of a light quantum, thereby implicitly proving its physical necessity before its theoretical status was clarified. At the same time, the already existing term photon began to acquire a stable usage following Lewis's 1926 proposal and became increasingly associated with Einstein's light quantum. By the mid-1920s, the central problem had shifted from whether light quanta were physically required to how radiation could be incorporated into the emerging quantum-mechanical formalism. This transition marks a key stage, illustrating how initial debates about the existence of light quanta gave way to their integration into a com

Cascade spin dynamics of excitons localized in indirect-band-gap (In,Al)As/AlAs quantum dots with type-I band alignment

Fri, 04 Sep 2026 00:00:00 +0000

We investigate the spin dynamics of excitons localized in type I (In,Al)As/AlAs quantum dots with an indirect in momentum space band structure. Polarized selective photoluminescence spectroscopy, i.e. fluorescence line narrowing, under magnetic fields up to 5 T applied in the Faraday geometry is employed. The experiment reveals a cascade spin evolution process of excitons in the indirect band-gap quantum dots: an initial short term spin dynamics associated with excited direct exciton states possessing a large oscillator strength is followed by electron relaxation into the X valley of the Brillouin zone and subsequent long term spin dynamics of indirect excitons. The two step mechanism manifests itself in the distinct features of the magnetic field dependences of photoluminescence: two component recovery of optical orientation, two component linear to circular polarization conversion and the presence of the linear polarization plane rotation. At the same time, suppression of the optical alignment shows one-component behavior governed by the spin dynamics of the indirect exciton states. Within the pseudospin formalism, we derive analytical expressions that quantitatively describe the

Microkelvin resolution thermometry at the nanometre scale

Fri, 04 Sep 2026 00:00:00 +0000

Accurate temperature readings of transient events at the nanometer scale are challenging due to the low sensitivity of available sensors. Nanodiamonds containing nitrogen-vacancy (NV) centers have been used for nanoscale thermometry in complex environments, including inside living cells. However, their performance has been limited by short coherence times and low photon counts. In this work, we use isotopically-purified dual-NV nanodiamonds and a bespoke quantum sensing chip to showcase an order of magnitude improvement in temperature measurement sensitivity compared with previous reports. We demonstrate robust temperature measurements with an error of 682 $μ$K, experimental sensitivities below 50 mK/$\surd \text{Hz}$ and a shot-noise limited sensitivity of 9.6 mK/$\surd \text{Hz}$. To confirm the utility of these high-performance nanothermometers, we quantify the temperature change induced by the thermometry measurement itself, specifically the optical excitation laser used to probe the NV spin state. In addition, we observe directly at the nanometre scale the transient heating caused by the exothermic mixing of dimethyl sulfoxide in water. Sub-millikelvin resolution and millikelv

Ancilla mediated steady-state engineering in open quantum systems

Fri, 04 Sep 2026 00:00:00 +0000

Engineering the properties of a reservoir and its coupling to a quantum system is a powerful tool for simulating quantum thermodynamic processes and for generating otherwise inaccessible steady states. Yet tailoring both the reservoir and its coupling within a single platform remains challenging. Here we introduce a platform, in which an ancilla qubit mediates the coupling of a target system to a reservoir, providing independent control over the interaction form, coupling strength, and effective reservoir temperature. Our implementation uses the electron spin of a single nitrogen-vacancy center in diamond as the ancilla and a proximal $^{13}$C nuclear spin as the target. By alternating engineered unitary interactions with dissipative ancilla resets, we realize dynamics naturally described by a collision model, enabling straight-forward tracking of the work, heat, coherence, and entropy generated at every collision. We experimentally demonstrate conventional thermalization and also realize anti-thermalization: the stabilization of the target system in a temperature opposite to that of its reservoir. Finally, harnessing this steady-state engineering, we utilize the nuclear spin as a

Neural networks learn to reconstruct multipartite entanglement from quantum marginals

Fri, 04 Sep 2026 00:00:00 +0000

Different sets of local correlations are not equivalent: some fragments of reduced data uniquely determine a global quantum state, while others leave it ambiguous. The quantum marginal problem asks whether a collection of reduced density matrices uniquely determines a compatible global quantum state. Although generic quantum states are uniquely specified by suitable sets of marginals, different collections of marginals are not equally informative: some uniquely determine the global state, whereas others leave it ambiguous. Identifying when uniqueness holds, and reconstructing the global state from partial information, remains computationally demanding and experimentally challenging. We show that information about the multipartite entanglement class and reconstructability in four-qubit systems is compactly encoded in small sets of two- and three-qubit marginals. Using semidefinite programming, we chart the reconstructability landscape across 49 inequivalent SLOCC entanglement classes and show that uniqueness strongly depends on both entanglement structure and marginal order. Neural networks trained only on reduced density matrices learn this structure directly. They accurately class

Transition between weak and strong measurements in the presence of post-selection

Fri, 04 Sep 2026 00:00:00 +0000

In the weak measurement regime, post-selection can result in the observation of anomalous weak values, seemingly contradicting the eigenvalue statistics observed when the measurement interaction is strong. Here, we investigate the dependence of meter statistics on measurement strength in a post-selected measurement. We find that the meter statistics in the intermediate regime between weak and strong measurements is nearly independent of measurement strength and show that, in this regime, the system performs a measurement of momentum on the meter. The transition between weak and strong measurements is explained by a reversal of the roles of the system and the meter, where the post-selection acts as a readout of information about the meter.

Shapley Valuation of Finite-Copy Quantum Data Depends on Physical Access

Fri, 04 Sep 2026 00:00:00 +0000

Data valuation asks how learning utility should be attributed to training data contributors. Most classical formulations begin after data have become reusable records, so the physical readout of the data is effectively fixed. Finite-copy quantum data are different: unknown states are consumable physical systems, and the same supplied states and downstream task can yield different Shapley values under different physical access models. Our framework makes this dependence explicit by treating physical access as a component of quantum data valuation itself. We establish an exact connection between physical-access advantage and contributor-level data valuation. For nested access models, we prove that the maximal downstream utility gain enabled by richer physical access exactly determines the largest symmetric Shapley ranking-reversal margin. More generally, for arbitrary access-model pairs, including non-nested ones, we derive an exact geometric characterization of the possible shifts of the full Shapley attribution vector. For fixed learning pipelines, we further obtain an operational Shapley-observable representation for finite-copy valuation. Numerical experiments demonstrate that id

Analytical model for polarization transfer during gas-phase collision events in spin-exchange optical pumping: Spin-$\frac{1}{2}$ $^{129}$Xe versus spin-$\frac{3}{2}$ $^{131}$Xe

Fri, 04 Sep 2026 00:00:00 +0000

Spin-exchange optical pumping (SEOP) is a method for producing spin-hyperpolarized noble gas nuclei, such as 129Xe and 131Xe, which are used in various magnetic resonance applications from fundamental physics to quantum sensing and medical imaging. In SEOP, optically polarized alkali-metal atoms transfer their spin polarization to the noble gas nuclei in gas-phase collision events via the hyperfine coupling (HFC) between the alkali valence electron and the noble gas nucleus. While the polarization transfer physics of spin $I = 1/2$ nuclei, such as 129Xe, is relatively well understood, that of spin $I > 1/2$ nuclei, such as 131Xe ($I = 3/2$), has been far less studied, and no rigorous theoretical model has been presented to date. To this end, we derive a simple analytical model for the upper limit, neglecting relaxation, of the SEOP polarization transfer, applicable to noble gases with arbitrary nuclear spin. Analytical evaluation of the Baker-Campbell-Hausdorff expansion for the time evolution of the spin density operator $\hatρ(t)$ reveals that only even-order terms in the HFC contribute to the polarization transfer, with the leading-order quadratic term being the most significant

Nitrogen Vacancy Centers in Diamond for Quantum Biosensing: Magnetometry Techniques, Platforms and Applications

Fri, 04 Sep 2026 00:00:00 +0000

Quantum sensing using nitrogen-vacancy (NV) centers in diamond has emerged as a powerful platform for detecting ultra-low magnetic fields under ambient conditions. Owing to their long spin coherence times, optical addressability, and compatibility with aqueous environments, it has found widespread applications in biosensing and bio-imaging. This review presents the fundamental principles and recent advances in NV-based quantum magnetometry for biosensing applications, with a particular focus on measurements in aqueous medium and at cellular and molecular length scales. We discuss the underlying spin physics of NV centers and highlight two primary detection modalities: optically detected magnetic resonance (ODMR) and T1 relaxometry-based sensing and how these approaches aids in the detection of both static magnetic fields and dynamic magnetic noise arising from biological processes. The review explores key application areas, including nanoscale nuclear magnetic resonance (NMR), monitoring of neural activity, detection of abnormal or rogue cells using NV-based platforms etc. In addition, strategies for enhancing sensitivity, such as surface functionalization of nanodiamonds, femtosec

One Bit of Collective Information Is Worth N ln 2 Bits of Local Information in a Many-Body Quantum Battery

Fri, 04 Sep 2026 00:00:00 +0000

Charging a quantum battery through a collective non-adiabatic stroke stores energy in a shared bosonic mode, but part remains locked in correlations with the collective spin and is inaccessible to cyclic unitaries acting on the mode alone. A demon holding one bit can unlock this energy, quantified by the daemonic ergotropy. We investigate the value of one bit and its dependence on where the information is obtained. Two protocols are compared at matched stored energy and matched information, using balanced two-outcome measurements carrying exactly one bit. We find that one bit about the collective coordinate unlocks N ln(2) times as much work as one bit about a single ion. For three stored-energy settings and N = 4-24, the measured scaling exponent is 0.990 +/- 0.043, while double extrapolation gives a prefactor of 0.69298 +/- 0.00044, within 0.02% of ln(2). To leading order, the daemonic gain equals nu mu^2 times the between-outcome variance of Jx, verified numerically to 1.3%. A balanced single-ion measurement resolves 1/4 of this variance, whereas a balanced collective split resolves (ln(2)/4)N. The microscopic origin of the prefactor remains open; a Gaussian median-split estimat

Interlayer Exciton Condensate Stiffness Is Non-Monotonic in Quantum Metric

Fri, 04 Sep 2026 00:00:00 +0000

Identifying the origin of the superfluid stiffness of electron-electron and electron-hole pair condensates is an important issue in flat-band physics. Here, we study the stiffness of bilayer exciton condensates using exact diagonalization and realistic Coulomb interactions across a wide variety of flat Chern band systems, including Landau levels, mixed Landau levels, and moiré bands. We find that stiffness is non-monotonic in the trace of the quantum metric and that it develops peaks when the band wavefunctions are engineered to be similar to those of Landau levels. The stiffness predicted by mean-field theory agrees quantitatively with exact diagonalization in these optimal cases, but systematically overestimates it otherwise. Flat bands with identical quantum geometry tensors can exhibit substantial differences in stiffness. The stiffness of condensates formed between moiré flat bands, which typically have strong variations in Berry curvature and quantum metric across their Brillouin zones, tends to be larger when the bands have non-zero Chern numbers and can be larger than that of Landau levels. Our results reveal a behavior that is richer than that suggested by simple geometric

Strong-Drive Limits in Josephson Circuits: From Chaos to an Unbound-Resonance Threshold

Fri, 04 Sep 2026 00:00:00 +0000

Strong microwave drives enable fast measurement and parametric control in superconducting circuits but can induce transitions out of the intended low-energy manifold. We develop a unified description of strong-drive limits in flux- and charge-driven Josephson circuits across drive frequency and dc flux bias. Using classical phase-space analysis and Floquet--Markov simulations, we identify distinct low- and high-frequency mechanisms. At low frequency, we characterize bound-state resonances and separatrix chaos and find that the flux-drive chaos threshold depends strongly on dc flux bias. At high frequency, these mechanisms are suppressed, and the dissipative steady state transfers from the central bound-state sector to outer resonances formed by above-barrier running trajectories. The resulting unbound-resonance threshold is nearly independent of drive frequency and circuit parameters over the regime studied and is controlled primarily by dc flux bias. Coherent simulations show that parametric operation persists beyond this threshold, but at a reduced rate, setting an effective upper bound on the achievable operation speed. We derive analytical criteria for both thresholds, validate

QMClaw: A Scalable General-purpose Framework for Quantum Measurement and Control

Fri, 04 Sep 2026 00:00:00 +0000

As quantum computing continues to scale, quantum measurement and control (QMC) are increasingly constrained by calibration workflow complexity and by requirements for low-latency execution, robust exception handling, and traceable workflow governance. Existing frameworks for QMC are specialized and task-specific, while language-model-based agents for QMC suffer from excessive latency and cannot satisfy the strict timing and control-density demands of large-scale quantum systems. Here we propose QMClaw, a general, workflow-oriented framework for QMC built, featuring a local-first, tool-governed, robust architecture. At its core is a RuleEngine-centered control layer that processes structured context, performs rule-based state transitions, and generates execution plans for typical calibration workflows. Language models are used only for natural-language interaction, high-level task understanding, and exception support, keeping the critical fast path efficient. We implement a single qubit tune-up workflow as a demonstration and validation using real quantum device dataset. We also prove that the framework achieves quantitatively acceptable levels in terms of resource cost, LLM calling

Research and simulation of analytical polarization control enabled by optical computing on an integrated photonics chip

Fri, 04 Sep 2026 00:00:00 +0000

Dynamic polarization controllers are key devices with broad applications in many fields. However, most on-chip polarization controllers still rely on traditional blind-search methods, whereas analytical optical-computing approaches remain insufficiently explored, particularly with respect to calibration and endless polarization control. With the accurate relative phase of Mach-Zehnder interferometer (MZI) being fully controllable on an integrated photonics chip, we present an analytical polarization control (APC) method using four phase shifters and optical computing, eliminating the need for the traditional inefficient blind-search procedure. The basic structures and operations of APC are clarified. The proposed calibration method and endless control method enable continuous APC while compensating for phase differences within the MZI structures. We simulate the influence of the endless control unit on polarization control and quantify the effect of the fourth phase difference on the output extinction ratio. With the fourth phase shifter, the phase difference encountered during Stokes vector measurement can be effectively compensated, and rotations around all three axes on the Poin

Qmes: Quantum Meta-Learning for Encoding Selection in Quantum Kernel Methods

Fri, 04 Sep 2026 00:00:00 +0000

Selecting an effective encoding quantum circuit is a key challenge in quantum kernel methods because different feature maps can lead to different performance. Conventional methods require constructing and evaluating every circuit for each new dataset, making it computationally expensive. We present Qmes, an open-source Python package that automatically recommends circuits through meta-learning. Qmes characterizes a dataset using classical complexity measures and queries a pre-trained model to recommend circuits without quantum evaluation at inference time. The package provides modular components for meta-feature extraction, quantum-kernel evaluation, recommender training, model selection, and user-defined circuit extension. We validate Qmes on 105 classification and 86 regression benchmark datasets. Qmes reduces the mean recommendation regret by 2.2x and 4.2x for classification and regression, respectively, compared to a non-adaptive baseline, with statistical significance confirmed via a paired Wilcoxon signed-rank test ($p < 10^{-4}$). Qmes thus enables efficient and practical encoding-circuit selection for quantum kernel methods.

Residual detuning in the laboratory-frame anti-Jaynes--Cummings model with a squeezed vacuum

Fri, 04 Sep 2026 00:00:00 +0000

The laboratory-frame anti-Jaynes--Cummings (AJC) interaction retains a residual detuning $2fλ$ that is absent from the rotating-frame model. We map two proposed remedies---a Kerr shift $χ(\hat a^\dagger\hat a)^2$ and collective Dicke coupling of $N$ two-level emitters---for a squeezed vacuum on that ladder ($r=1$, $\langle n\rangle=\sinh^2 r\simeq 1.38$). All quoted contrasts are the amplitude of the first turning point of the atomic ground-state population, which coincides with the two-level formula $\mathcal{C}=1/[1+(2f+χ)^2]$ at $r=0$ to $10^{-9}$. Three results follow. (i)~A single Kerr strength never restores unit contrast at $r=1$; the $r=0$ $n$-dependent shift $χ(2n+1)$ cannot cancel $2fλ$ on every occupied Fock component. (ii)~The exact $r=1$ contrast at $χ=0$ is not reproduced by an incoherent sum $\sum_n P_n(r)\,\mathcal{C}_n$ built from the $r=0$ two-level formula; pointwise deviations are several tenths. (iii)~Collective coupling raises the contrast systematically. At $f=5$ one finds $\mathcal{C}=0.140$ ($N=1$) and $\mathcal{C}=0.575$ ($N=8$), above the unsqueezed value $8/[8+(2f)^2]=0.074$. The $N=16$ point at this $f$ remains truncation-limited and is not quoted to th

Quantinuum and Aramco Sign MOU to Explore Industrial Quantum Computing

Thu, 03 Sep 2026 00:00:00 +0000

Insider Brief Quantinuum and Aramco have signed a non-binding MoU to explore industrial quantum computing applications and potential research collaboration in fault-tolerant quantum computing. The companies plan to identify energy and digital transformation challenges that could be suitable for quantum computing research and benchmark different quantum computing modalities. The agreement also covers technical onboarding and knowledge exchange as Aramco evaluates how future quantum systems could address scientific and industrial problems. PRESS RELEASE — Quantinuum , a leading quantum computing company, today announced the signing of a non-binding MOU with Aramco , one of the world’s leading integrated energy and chemicals companies, to explore a series of industrial use cases, enhance quantum computing capabilities, and prepare for a potential research collaboration focused on fault-tolerant quantum computing. Under the MOU, the companies intend to undertake preliminary technical onboarding and engage in knowledge exchange activities. They will also identify Aramco ‘s challenges that may be suitable for quantum computing research with an emphasis on solving comple

Quantum Motion Raises Additional Funding for Silicon Quantum Computing

Thu, 03 Sep 2026 00:00:00 +0000

Insider Brief Quantum Motion has announced the second close of its Series C funding round, with new investments from Imec.ventures, Lansdowne Partners, Sony Innovation Fund, S3 Ventures and Inkef. The funding will support silicon quantum computing development, custom silicon co-development, semiconductor manufacturing partnerships and the company’s international expansion, including its new U.S. lab in Maryland. Quantum Motion is targeting fault-tolerant quantum hardware based on silicon CMOS manufacturing, with the company also participating in Stage B of DARPA’s Quantum Benchmarking Initiative. PRESS RELEASE — Quantum Motion , the leader in silicon spin-based quantum computing, today announced the second close of its series C funding round to accelerate the scale-up of its fault-tolerant quantum hardware. This second close of the series C round led by DCVC and Kembara contributes investments from Imec.ventures, Lansdowne Partners, Sony Innovation Fund, S3 Ventures, and Inkef. The funding will drive custom silicon co-development, leverage global semiconductor manufacturing pipelines and build upon key milestones including international expansion, notably opening US lab in Ma

Quantum control algorithm looks to explain how birds migrate

Thu, 03 Sep 2026 00:00:00 +0000

The hidden world of quantum mechanics exists at scales many orders of magnitude smaller than living organisms, yet scientists have long theorized that quantum effects play an important role in biology. Birds' ability to sense magnetic fields during migration is one of the best-known mysteries in this field, with leading theories suggesting that this sensing could be achieved by exploiting quantum entanglement.

SEEQC Signs MoU with Taiwan Quantum Industry Technology Promotion Office to Build Cryo-Chip Supply Chain

Thu, 03 Sep 2026 00:00:00 +0000

Digital quantum computing platform developer SEEQC has signed a Memorandum of Understanding (MoU) with Taiwan’s Quantum Industry Technology Promotion Office (QITPO)—an agency established under the Ministry of Economic Affairs (MOEA)—to formalize a cross-border quantum technology and supply-chain partnership. Signed at SEMICON Taiwan 2026 in Taipei, the agreement creates a structured framework for technology transfer, joint [...] The post SEEQC Signs MoU with Taiwan Quantum Industry Technology Promotion Office to Build Cryo-Chip Supply Chain appeared first on Quantum Computing Report .

IBM’s Nighthawk r2 Quantum Processor Targets a 25-Fold Increase in Circuit Speed

Thu, 03 Sep 2026 00:00:00 +0000

Insider Brief IBM has released Nighthawk r2, a 120-qubit processor designed to deliver more useful computation through substantially faster qubit resets. The processor can execute more than 100,000 circuits per second, 25 times the throughput of IBM ’s Heron systems, while maintaining comparable gate accuracy. Nighthawk r2 has demonstrated accurate estimates on circuits containing more than 7,500 gates and supports in-circuit resets for quantum error-correction research. IBM has released its fastest quantum processor to date, using a new qubit-reset system to run substantially more computations without sacrificing accuracy. The IBM Quantum Nighthawk r2 processor can execute more than 100,000 quantum circuits per second, according to a post published on the IBM Quantum site . That is 25 times the circuit throughput of the company’s Heron processors , which run about 4,000 circuits per second. Nighthawk r2 has 120 programmable quantum bits, or qubits, the same number as the first version of Nighthawk. Its main advance is speed rather than size. IBM said the processor reduces the time required to reset qubits between circuit runs, addressing a bottleneck that limits how much work a qu

Classiq Expands in Taiwan via Go-to-Market Partnerships with Scientek and Kensho

Thu, 03 Sep 2026 00:00:00 +0000

Quantum software engineering platform Classiq Technologies has entered into dual market development agreements in Taiwan with technology distributors Scientek Corporation (a Zen Voce company) and Kensho. Timed alongside SEMICON Taiwan 2026, the partnerships establish local distribution, customer enablement, and joint application R&D channels across Taiwan’s semiconductor manufacturing, defense, material science, and academic research ecosystems. [ [...] The post Classiq Expands in Taiwan via Go-to-Market Partnerships with Scientek and Kensho appeared first on Quantum Computing Report .

Andhra University Plans Centres of Excellence for Quantum, AI and Semiconductors

Thu, 03 Sep 2026 00:00:00 +0000

Insider Brief Andhra University plans to establish Centres of Excellence in quantum technology, AI systems and semiconductors over the next two to three years. Vice-Chancellor G.P. Raja Sekhar said the proposed laboratories would focus on applying quantum technology and AI research to practical solutions. Speakers at the QUEST-AI conference also highlighted hybrid quantum-classical computing, sustainable data centres, semiconductor development and workforce skills as areas for regional development.\ Photo Credit: KR DEEPAK . Andhra University intends to set up Centres of Excellence covering quantum technology, AI systems, and semiconductors, Vice-Chancellor G.P. Raja Sekhar said Tuesday, The Hindu reported . Raja Sekhar made the announcement while opening a three-day international conference on Quantum-Enhanced Sustainable Technologies for AI Systems (QUEST-AI), hosted by the cluster departments of Andhra University College of Engineering in Visakhapatnam. “Following the conclusion of the centenary celebrations of Andhra University, we are focusing on quality developmental activities,” Raja Sekhar said, as quoted by the publication. He said he expects the conference dis

AI suggests new physics experiments that could outperform human-designed setups

Thu, 03 Sep 2026 00:00:00 +0000

Research means asking questions of the universe. For centuries, clever minds have advanced science by devising ingenious experiments designed so their results reveal something about the laws of nature as clearly and unambiguously as possible.

Giesecke+Devrient Joins European uPQComing Consortium to Develop Quantum-Safe eID Operating Systems

Thu, 03 Sep 2026 00:00:00 +0000

Munich-based security technology group Giesecke+Devrient (G+D) has joined uPQComing (Enhancing Cyber-Resilience for the Upcoming Post-Quantum Era), a European research consortium co-funded by the European Union's Chips Joint Undertaking (Chips JU). The project focuses on migrating critical public digital infrastructure and resource-constrained embedded secure elements—specifically smart card integrated circuits and electronic identity (eID) operating systems—to Post-Quantum [...] The post Giesecke+Devrient Joins European uPQComing Consortium to Develop Quantum-Safe eID Operating Systems appeared first on Quantum Computing Report .

Quantum-optical spin glass could improve how AI remembers and learns

Thu, 03 Sep 2026 00:00:00 +0000

A new study has demonstrated that it is possible to make a network of atoms and photons that could improve how artificial intelligence stores and recalls memories. This network, called a quantum-optical spin glass, works as an associative memory, a form of AI that enables the recall of full memories from partial information—much like how humans can recognize a person's face in a blurred photograph.

Pasqal and True Nexus Encode Protein Gelation Structures on Neutral-Atom QPUs

Thu, 03 Sep 2026 00:00:00 +0000

Neutral-atom quantum hardware vendor Pasqal (Nasdaq: PSQL) and Saudi deep-tech startup True Nexus have announced a technical milestone in applying quantum computing to structural biology. Supported by Saudi Arabia’s Ministry of Communications and Information Technology (MCIT), the teams successfully encoded protein structures associated with molecular gelation—the phase transition that converts protein liquids into gels to [...] The post Pasqal and True Nexus Encode Protein Gelation Structures on Neutral-Atom QPUs appeared first on Quantum Computing Report .

Rigetti and Purdue University Demonstrate Quantum Preconditioning Framework for Constrained Optimization

Thu, 03 Sep 2026 00:00:00 +0000

Quantum computing developer Rigetti Computing and researchers from Purdue University have published joint research extending Rigetti's quantum preconditioning framework to hard-constrained combinatorial optimization problems. By using two-point variable correlations extracted from shallow Quantum Approximate Optimization Algorithm (QAOA) circuits to modify the objective function of commercial Mixed-Integer Programming (MIP) solvers, the team demonstrated that quantum preconditioning [...] The post Rigetti and Purdue University Demonstrate Quantum Preconditioning Framework for Constrained Optimization appeared first on Quantum Computing Report .

SEALSQ and wolfSSL Add wolfTPM Support for QVault Post-Quantum TPM

Thu, 03 Sep 2026 00:00:00 +0000

Insider Brief SEALSQ and wolfSSL have announced wolfTPM support for the SEALSQ QVault TPM, adding software support for post-quantum algorithms implemented in the TPM hardware. The integration supports ML-DSA, Hash-ML-DSA and ML-KEM parameter sets, with testing performed on physical QVault hardware and wolfSSL’s firmware TPM environment. wolfTPM includes QVault-specific support, a new pqc_ctrl tool, post-quantum examples, build instructions and hardware benchmarks for embedded development. PRESS RELEASE — SEALSQ Corp (NASDAQ: LAES) (“SEALSQ” or “Company”), a company that focuses on developing and selling Semiconductors, PKI, and Post-Quantum technology hardware and software products, and wolfSSL Inc., a recognized leader in embedded cryptography, today announced wolfTPM support for the SEALSQ QVault TPM. Market First The SEALSQ QVault TPM is on track to be the first shipping TPM 2.0 device on the market to implement in silicon the post-quantum algorithms introduced in the Trusted Computing Group’s latest TPM 2.0 v1.85 specification. wolfTPM gives developers a direct path to use QVault’s ML-DSA and ML-KEM capabilities in embedded applications. Perfect In

Argonne and JPMorganChase Develop New Method to Study QAOA at Scale

Thu, 03 Sep 2026 00:00:00 +0000

Insider Brief Researchers from JPMorganChase and Argonne National Laboratory developed a method to evaluate high-depth QAOA calculations for large Sherrington–Kirkpatrick model problems without running the algorithm end to end. The approach maps the QAOA state in the infinite-size limit to a spin-boson system, allowing researchers to use matrix product state simulations instead of more costly calculations. The researchers used supercomputers at DOE computing facilities to simulate the system and optimize QAOA parameters, providing a way to study the performance and limits of quantum optimization algorithms. PRESS RELEASE — Quantum computers have arisen as a possible solution for highly complex mathematical problems, offering “quantum advantage” over classical computers in certain cases. The Quantum Approximate Optimization Algorithm (QAOA) is a leading candidate for realizing this advantage, and some success has been achieved for small problems. But demonstrations on large problems have remained too computationally costly to run on classical computers and current quantum hardware. Researchers from JPMorganChase and the U.S. Department of Energy ’s (DOE) Argonne National Labo

SEALSQ Integrates wolfTPM Support into Post-Quantum Silicon Semiconductor Platform (QVault TPM)

Thu, 03 Sep 2026 00:00:00 +0000

Post-quantum semiconductor hardware vendor SEALSQ Corp (NASDAQ: LAES) and embedded cryptography developer wolfSSL Inc. have announced native wolfTPM software support for SEALSQ’s QVault TPM hardware security chip. Designed to implement post-quantum cryptography (PQC) primitives in silicon under the Trusted Computing Group’s (TCG) TPM 2.0 v1.85 specification, the integration provides an open-source software layer to execute [...] The post SEALSQ Integrates wolfTPM Support into Post-Quantum Silicon Semiconductor Platform (QVault TPM) appeared first on Quantum Computing Report .

BESIII sets world's most stringent direct limit on Lambda hyperon electric dipole moment

Thu, 03 Sep 2026 00:00:00 +0000

The BESIII Collaboration, led by the Institute of High Energy Physics of the Chinese Academy of Sciences, has achieved the world's most precise measurement of the electric dipole moment (EDM) of the Lambda (Λ) hyperon using quantum-entangled Λ–anti-Λ pairs produced in J/ψ decays. The result improves the experimental sensitivity by about three orders of magnitude compared with the previous measurement, providing a new way to probe charge-parity (CP) violation in particles containing strange quarks.

George Mason University Partners with TreQ to Install $7.7M Open-Architecture Quantum QPU in Virginia

Thu, 03 Sep 2026 00:00:00 +0000

George Mason University has entered into a strategic hardware partnership with Oxford-based quantum infrastructure firm TreQ to deploy an open-architecture quantum computer at its Northern Virginia campus. Supported by catalytic funding from the Virginia Innovation Partnership Corporation (VIPC) alongside university capital, the $7.7 million system will represent the first U.S. deployment of TreQ’s proprietary Open [...] The post George Mason University Partners with TreQ to Install $7.7M Open-Architecture Quantum QPU in Virginia appeared first on Quantum Computing Report .

Relativistic position verification with coherent states

Thu, 03 Sep 2026 00:00:00 +0000

Dual-purpose qubit design could speed operations while cutting quantum errors

Thu, 03 Sep 2026 00:00:00 +0000

Researchers from MIT have designed a new qubit architecture that enables qubits to interact with each other much more quickly while remaining very stable. This advance could someday help scientists build practical quantum computers that can run long, complex algorithms with high accuracy.