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Quantum Materials & Devices: Hardware Components & Fabrication

Quantum materials news: quantum device fabrication, superconductors, quantum dots, 2D materials. Quantum hardware components & substrates.

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Quantum materials and devices form the foundational hardware layer enabling all quantum technologies, requiring specialized materials with precise quantum properties including superconductors, topological insulators, 2D materials like graphene, and semiconductor heterostructures for qubit fabrication.

India's Quantum Materials and Devices Initiatives

India's National Quantum Mission includes Quantum Materials & Devices as the fourth thematic vertical with dedicated funding. The QMD Tech Foundation at IIT Delhi serves as the Thematic Hub on Quantum Materials and Devices, established under the T-Hub framework of NQM. The hub focuses on developing indigenous materials for quantum technologies including substrates for superconducting circuits, quantum dots for spin qubits, and specialized semiconductors.

The ₹720 crore investment for quantum fabrication facilities announced in November 2025 supports this vertical, with facilities at: IISc Bengaluru: Quantum computing fabrication for superconducting, photonic, and spin qubits (3-5 qubits per chip initially, scaling to 20-100 qubits); IIT Bombay: Quantum sensing and device fabrication; IIT Delhi: Quantum materials and packaging; IIT Kanpur: Smaller facility for specialized devices.

The Indian Institute of Technology Madras Centre for Quantum Information, Communication and Computing (CQuICC) houses India's first remotely accessible semiconductor qubit facility, capable of fabricating 3-5 qubit chips per run with 95% device yield.

Research Areas: Superconducting materials: Niobium and aluminum thin films for Josephson junctions; Semiconductor quantum dots: Silicon and III-V materials for spin qubits; 2D materials: Graphene, transition metal dichalcogenides for novel qubit designs; Topological materials: Research into materials exhibiting Majorana zero modes; Photonic materials: Silicon photonics, nonlinear optical crystals for quantum light sources.

The Defence Research and Development Organisation (DRDO) develops quantum materials for defense applications including secure communications and sensing. The Department of Atomic Energy (RRCAT, Indore) provides specialized laser and materials processing capabilities for quantum device fabrication. The NQM targets developing superconductors, novel semiconductor structures, and quantum materials for memory and device fabrication as key deliverables within the 8-year mission timeline.

Infleqtion’s chip powers Japan’s first full quantum system
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Infleqtion’s chip powers Japan’s first full quantum system

Infleqtion’s quantum processing unit is now powering “Shunkai,” Japan’s first operational full-stack neutral-atom quantum computer with an initial capacity of approximately 50 qubits and planned expansion to around 500. The collaboration represents a step beyond research and development for the country, supported by the Japan Science and Technology Agency’s Quantum Moonshot program, for which Infleqtion was the sole foreign quantum partner, the company says. “This milestone marks a pivotal moment for Japan’s quantum ambitions and Infleqtion’s role in advancing production-ready quantum platforms,” says Pranav Gokhale, Chief Technology Officer at Infleqtion. Shunkai System: Infleqtion’s Neutral Atom QPU Powers Japan’s Quantum Computer Currently functioning with approximately 50 qubits, Shunkai is projected to expand to around 500 qubits as the project progresses, demonstrating increased computational capacity. The system’s development signifies a move toward operational quantum computing for Japan, validating the potential of neutral-atom architecture. The Ohmori Moonshot project, entering its next phase in April 2026, will concentrate on enhancing system integration, stability, and scalability, with a long-term goal of creating a high-performance, fault-tolerant quantum computer with up to 10,000 physical qubits. The IMS team intends to make Shunkai accessible to external users, fostering the advancement of quantum error correction research and application development within academic and industrial settings. Infleqtion’s contribution extends beyond hardware; the company’s Superstaq quantum computing software platform is integral to the system’s functionality, delivering the programmability and fidelity control essential for advanced quantum systems, according to the company. This collaboration underscores Infleqtion’s role in delivering production-ready quantum platforms and solidifies Japan’s position in the rapidly evolving field of quantum technology. This milesto

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A micromechanical qubit might last a full secondquantum-computing

A micromechanical qubit might last a full second

Researchers at the University of Surrey and Northwestern University are proposing a new type of qubit built not with superconducting circuits, but with quantized oscillations in superfluid helium. The device, consisting of a superfluid weak link and a mechanical element, is predicted to function as a charge-neutral quantum bit with micron-sized dimensions and exhibit millisecond-scale coherence time. This approach leverages both dissipationless mass flow and Josephson tunneling demonstrated in superfluid helium, offering a distinct path toward scalable quantum information processing. The work shows this quantum regime is within reach for a range of device designs. Superfluid Helium Weak Link as Josephson-like Element A qubit capable of maintaining quantum coherence for millisecond-scale times, despite being built with micron-sized components, is proposed by Priya Sharma of the University of Surrey and Jens Koch of Northwestern University. This potential advancement differs from prevalent qubit research centered on superconducting circuits, instead leveraging the unique properties of superfluid helium. The device, detailed in recent work, relies on quantized oscillations within a superfluid weak link coupled to a mechanical element, offering a charge-neutral alternative to traditional qubit designs. Researchers envision a cylindrical cell containing superfluid helium-3, incorporating a nanoaperture acting as a weak link; this link connects the cell to a superfluid reservoir. The design incorporates an elastic plate, responsive to pressure changes induced by superfluid motion, functioning as a fluidic capacitor within an equivalent circuit. This arrangement allows for the creation of discrete, resolvable energy levels at millikelvin temperatures, a prerequisite for maintaining the superfluid state and enabling quantum behavior. The proposed Superfluid Helium Oscillator Quantum (SHOQ) device operates by establishing a phase difference across the weak link, initiating a

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Researchers Cut Quantum Error by 4.7 Times with Mitigationquantum-computing

Researchers Cut Quantum Error by 4.7 Times with Mitigation

The researchers of The Catholic University of America, University of Deusto, Universidad de los Andes demonstrate the practical benefits of quantum error management techniques as quantum processors scale. While current devices surpass one hundred qubits, inherent noise restricts circuit performance and full error correction remains impractical. This team benchmarked three commercial error suppression and mitigation solutions Qiskit Runtime, Q-CTRL Performance Management, and Qedma QESEM, on an IBM Quantum Heron r3 processor with 156 qubits. Their analysis, utilising both Sampler and Estimator workloads, reveals substantial performance improvements through managed error mitigation, with Q-CTRL and QESEM reducing aggregate error by factors of 3.10 and 4.70 respectively, compared to raw execution, though these gains involve distinct trade-offs in execution time. These findings highlight the importance of error management strategies in maximising the utility of near-term quantum hardware. Scaling quantum processors beyond one hundred qubits necessitates addressing the limitations imposed by noise, as full quantum error correction remains too complex for routine use. The team assessed how well these commercial tools manage errors on quantum computers. These tools, including those from Q-CTRL and Qedma, aim to improve performance without fully correcting errors, a complex task for current systems. The research compared these solutions on IBM’s 156-qubit processor using both ‘Sampler’ workloads which analyse raw data, and ‘Estimator’ workloads which measure specific quantum properties against known results. Daniel Sierra-Sosa and colleagues have independently assessed commercial tools designed to manage errors in quantum computations. As quantum processors surpass one hundred qubits, noise remains a key limitation, and full quantum error correction is currently impractical. Instead, researchers are employing techniques akin to spellcheck, known as quantum error mitigation,

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Completed: Yale Facility for Free-Space Quantum Link Across Long Island Soundquantum-computing

Completed: Yale Facility for Free-Space Quantum Link Across Long Island Sound

Yale University has completed an optical facility in New Haven forming the third facility in a free-space optical quantum link with Stony Brook University and Brookhaven National Laboratory. The demonstrated 13-mile Stony Brook–Brookhaven leg has transmitted quantum states and entangled photons through open air, adding wireless capability to the 161-mile fiber network. Technical details on adaptive optics, the forthcoming 30-mile Q-LATS connection, and SCY-QNet integration show the path toward extended entanglement distribution across Long Island Sound. The post Completed: Yale Facility for Free-Space Quantum Link Across Long Island Sound appeared first on The Qubit Report.

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Soongsil University Team Estimates Ground-State Energy with 0.00 mHa Deviationquantum-computing

Soongsil University Team Estimates Ground-State Energy with 0.00 mHa Deviation

Researchers at Soongsil University and collaborating institutions have demonstrated a hybrid quantum-classical approach for calculating molecular ground-state energies using Sample-Based Quantum Diagonalization (SQD). The study evaluates the molecular systems HeH⁺, ArH⁺, and H₂O, showing that the technique can accurately reproduce potential-energy curves while operating within the capabilities of today’s quantum hardware. The results demonstrate that SQD can achieve accuracy comparable to established quantum chemistry methods, highlighting its potential as a practical tool for studying increasingly complex molecular systems on near-term quantum computers. Until now, accurate ground-state energy calculations for molecules required computationally demanding methods like coupled-cluster singles and doubles (CCSD). The deviations from complete active space configuration interaction references were as low as 0.00 mHa for HeH^+, demonstrating the accuracy of this new approach for benchmark systems. The team successfully applied SQD to helium hydride ion, argon hydride ion, and water, validating its potential for broader use in understanding molecular behaviour and astrophysical systems. Unlike traditional methods, such as coupled-cluster singles and doubles (CCSD), which are akin to painstakingly assembling a complex jigsaw puzzle requiring significant computational resources, SQD builds up a picture of a molecule’s lowest energy state by taking many ‘snapshots’ from a quantum computer and combining them, much like creating a detailed mosaic from individual tiles. This is particularly significant as CCSD, while highly accurate, scales poorly with system size, becoming intractable for all but the smallest molecules. The team successfully applied SQD to helium hydride ion, argon hydride ion, and water, achieving deviations from benchmark calculations as low as 0.00 mHa for helium hydride ion. This demonstrates the potential of SQD for complex systems and offers a pathway to

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IonQ vs. Quantum Computing Inc.: Which Quantum Computing Stock Is a Better Buy in 2026?quantum-computing

IonQ vs. Quantum Computing Inc.: Which Quantum Computing Stock Is a Better Buy in 2026?

As the race for quantum supremacy intensifies, choosing between IonQ (IONQ -7.25%) and Quantum Computing Inc. (QUBT -6.78%), which refers to itself as QCi, requires a careful look at their vastly different scales and unique hardware approaches.IonQ uses trapped-ion technology to build systems accessible through major cloud platforms, while QCi focuses on photonic chips and room-temperature hardware. Both companies represent high-risk, high-reward plays in a nascent industry where long-term commercial viability remains the primary hurdle for investors to consider.The case for IonQIonQ specializes in developing quantum hardware using trapped ions. The company primarily sells access to its systems through the cloud computing ecosystem, partnering with giants such as Amazon-owned AWS. Revenue concentration remains a risk, as the company is heavily reliant on a small number of major customers, and customer concentration like this adds a layer of risk to the business.In its latest annual report, filed for fiscal year (FY) 2025, revenue reached $130 million, representing a significant jump of 202% compared to the previous year. Despite this growth, the company reported a net loss of $510.4 million for the period. This widening loss is common in the early stages of capital-intensive hardware development, though the triple-digit top-line growth suggests increasing demand for its trapped-ion systems among commercial and research clients.As of its December 2025 balance sheet, the company's debt-to-equity ratio is zero, which means total debt is negligible relative to its shareholder equity. The current ratio stands at 15.5x, a measure of its ability to cover short-term debts with assets that can be converted to cash within a year. Free cash flow, which is cash from operations minus capital expenditures, was a negative $299.6 million in FY 2025, reflecting high costs of building out its infrastructure.The case for Quantum Computing Inc.According to its latest annual report for

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Jyv Team Models Quantum Service Threats across Pipeline Stagesquantum-computing

Jyv Team Models Quantum Service Threats across Pipeline Stages

Researchers at the University of Jyväskylä have developed a comprehensive security framework for Quantum-as-a-Service (QaaS) platforms, providing one of the first end-to-end analyses of vulnerabilities across cloud-based quantum computing systems. As more organisations access quantum processors remotely through cloud services, understanding security risks throughout the entire computation pipeline has become increasingly important. The study introduces a six-stage model of the QaaS workflow and applies the STRIDE threat-modelling methodology to systematically identify attack vectors from software development to quantum execution and hybrid post-processing. Quantum-as-a-Service enables users to access quantum hardware through cloud platforms without owning or maintaining specialised equipment. Many widely used quantum algorithms, including the Variational Quantum Eigensolver (VQE), Quantum Approximate Optimisation Algorithm (QAOA), and Quantum Machine Learning (QML) applications, rely on repeated interactions between classical computers and remote quantum processors. While previous research has demonstrated individual attacks against specific components of these systems, a unified assessment of threats across the complete workflow has been lacking. To address this gap, the researchers decomposed the QaaS pipeline into six distinct stages covering the developer environment, program compilation, cloud infrastructure, quantum hardware, measurement, and hybrid quantum-classical iteration. They then applied the STRIDE framework—covering spoofing, tampering, repudiation, information disclosure, denial of service, and privilege escalation—to each stage, creating a structured matrix that classifies quantum-specific threats, inherited classical cybersecurity risks, and plausible attack scenarios. The analysis revealed that security vulnerabilities extend well beyond the quantum processor itself. In particular, the study highlights two areas that have received relatively littl

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Infleqtion Collaboration with Japan Moonshot Program Achieves Major Milestone: “Shunkai” Neutral Atom Quantum Computer Now Operational
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Infleqtion Collaboration with Japan Moonshot Program Achieves Major Milestone: “Shunkai” Neutral Atom Quantum Computer Now Operational

Infleqtion’s quantum processing unit advances Japan’s first operational full-stack neutral-atom quantum computer, reinforcing momentum toward scalable quantum systems. LOUISVILLE, Colo. | August 24, 2026 | Infleqtion (NYSE: INFQ), a global leader in quantum computing and quantum sensing powered by neutral-atom technology, has helped Japan reach a major quantum milestone, supporting a research team led by Professor Kenji Ohmori at the Institute for Molecular Science (IMS), part of the National Institutes of Natural Sciences, in launching the country’s first operational neutral-atom full-stack quantum computer. Infleqtion was also the only foreign quantum partner selected by the Japan Science and Technology Agency (JST) for its Quantum Moonshot program. Infleqtion contributed its quantum processing unit to the program, in collaboration with the Ohmori group at IMS, as one of the principal investigators of the Moonshot project led by Professor Ohmori, supporting the transition from research and development to an operational full-stack quantum computing platform. The system, referred to as “Shunkai”, is initially expected to operate with approximately 50 qubits, with plans to scale to around 500 qubits as development progresses. “This milestone marks a pivotal moment for Japan’s quantum ambitions as well as Infleqtion’s role in advancing production-ready quantum platforms at scale,” said Pranav Gokhale, Chief Technology Officer at Infleqtion. “Bringing a full-stack quantum system into production operation is a meaningful step toward fault-tolerant quantum computing that also serves as strong validation of neutral-atom architecture. Our quantum processing unit delivers the programmability, scalability and fidelity control that next-generation systems demand.” As part of the next phase of the Ohmori Moonshot project that has just started in April 2026, the IMS team will focus on improving system integration, stability, and scalability, with the goal of realizing a high-pe

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Researchers Identify Conditions for Minimising Errors in Temperature Estimationquantum-computing

Researchers Identify Conditions for Minimising Errors in Temperature Estimation

Precise determination of an unknown temperature relies on effective quantum probes and estimation strategies that minimise disturbance to the measured system. Investigations using two-qubit probes within a framework allowing exact calculations of energy loss through dephasing, where quantum coherence is lost, have been completed at Mohammed V University in Rabat and Université Polytechnique Hauts-de-France. Conditions optimising temperature measurements utilising pairs of quantum bits, known as qubits, are established by considering how they share an external ‘bath’ rather than assessing individual environmental factors. The team explored scenarios where energy loss occurs through dephasing; this represents the loss of coherence within a quantum system. This approach uses correlations between qubits which improves thermal sensing at short timescales compared to conventional methods relying on systems reaching equilibrium. Techniques for precise temperature determination using quantum mechanics are being refined at Mohammed V University in Rabat and Université Polytechnique Hauts-de-France, potentially surpassing classical thermometer limitations. Their work centres on utilising pairs of quantum bits, known as qubits, as probes, examining their behaviour within a ‘pure-dephasing framework’ where energy loss occurs through the decay of coherence without changing overall energy levels. Pure-dephasing describes how quickly ‘frosting randomises information about an original image, similar to the loss of phase coherence in these qubits. The researchers investigated scenarios involving shared environmental interactions between qubits; such configurations outperform those with individual environments at short timescales due to induced correlations. This analysis identifies key conditions for minimising estimation errors by considering parameters governing energy dissipation, akin to adjusting a dial controlling heat release from an electrical component. Multiple correlated

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Japan Operationalizes First Full-Stack Neutral-Atom Quantum Computer “Shunkai”quantum-computing

Japan Operationalizes First Full-Stack Neutral-Atom Quantum Computer “Shunkai”

Japan Operationalizes First Full-Stack Neutral-Atom Quantum Computer “Shunkai” The Institute for Molecular Science (IMS), part of Japan’s National Institutes of Natural Sciences (NINS), has announced that Japan’s first full-stack neutral-atom quantum computer, named “Shunkai” (春海), is now operational. Led by Project Manager Professor Kenji Ohmori under Goal 6 of the Japanese Cabinet Office / JST Moonshot Research and Development Program, the platform was built through a industry-academia consortium partnering with Hitachi, Ltd. for the software stack and Infleqtion, Inc. for the Quantum Processing Unit (QPU) hardware stack. [ IMS Neutral-Atom System Architecture: “Shunkai” ]Hardware Stack (QPU)Software & Control StackScale & Roadmap Targets• Neutral Rubidium Atoms• Hitachi Software Stack• Phase 1: 50 Physical Qubits• Optical Tweezer Arrays• Infleqtion QPU Electronics• Phase 2: 500 Physical Qubits• Room-Temp Qubit Control• Dynamically Moved Atoms• 2031 Target: 10k FTQC Qubits Full-Stack Integration and Optical Tweezer Control The “Shunkai” system is named after Harumi (Shunkai) Shibukawa, the Edo-period astronomer who designed Japan’s first indigenous calendar based on celestial calculations. The full-stack platform integrates user-level software directly down to physical laser control and readout systems: Optical Tweezer Qubit Trapping: Single neutral atoms are trapped in a two-dimensional grid using optical tweezers created by tightly focused laser beams through high-NA objective lenses. Quantum logic gates are driven via targeted microwave and laser pulses, with individual readout executed via high-resolution fluorescence cameras. Room-Temperature Reconfiguration: Operating without cryogenic dilution refrigerators, the platform leverages dynamic atom transport to physically move qubits during runtime, enabling all-to-all connectivity and reconfigurable circuit topologies. Consortium Ecosystem: Hardware component integration and QPU packaging were developed

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All entangled qubits of a certain type can steer, study findsquantum-computing

All entangled qubits of a certain type can steer, study finds

Yu-Xuan Zhang of Nankai University and Jing-Ling Chen have proven that every entangled rank-2 two-qubit state is EPR steerable. This resolves a long-standing question of how entanglement and EPR steering relate for rank-2 two-qubit states, building on Gisin’s theorem which established a link for pure states. The researchers used a local-unitary parametrization of rank-2 two-qubit states and a state-dependent nonlinear steering inequality in their proof, establishing these states as certifiable resources for quantum information technologies. Rank-2 Two-Qubit States are Universally EPR Steerable This result extends Gisin’s theorem, which previously linked pure-state entanglement to Bell nonlocality, by proving a similar connection for a broader class of quantum states, specifically those with a rank of two. EPR steering describes a quantum phenomenon where one party, through local measurements, can seemingly prepare the state of another entangled particle, a concept central to quantum communication and computation. The ability to reliably generate and verify steerable states is crucial for applications like quantum teleportation and quantum key distribution, where secure information transfer depends on the unique properties of entangled particles. The researchers highlight the practical implications of their findings in their published work. The team’s work builds on decades of research into quantum nonlocality, beginning with the 1935 EPR paradox and Bell’s theorem in 1964, which further developed the EPR paradox and laid the groundwork for understanding the fundamental differences between quantum mechanics and classical physics. Prior investigations established a hierarchy of quantum nonlocality, with Bell nonlocality being the strongest form, EPR steering intermediate, and entanglement the most general. However, the precise relationship between these forms, particularly for rank-2 two-qubit states, remained an open question until now. In 1989, Werner demonstrated t

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Pasqal and Eleven Ventures Form Joint Venture to Scale Neutral-Atom Quantum Systems Across Saudi Arabia and MENA Regionquantum-computing

Pasqal and Eleven Ventures Form Joint Venture to Scale Neutral-Atom Quantum Systems Across Saudi Arabia and MENA Region

Pasqal and Eleven Ventures Form Joint Venture to Scale Neutral-Atom Quantum Systems Across Saudi Arabia and MENA Region Neutral-atom quantum computing developer Pasqal and Saudi Arabian investment platform Eleven Ventures have signed an agreement to establish a commercial joint venture—Pasqal Arabia—to deploy, commercialize, and scale neutral-atom quantum processors across the Kingdom of Saudi Arabia and the broader Middle East and North Africa (MENA) region. Timed to coincide with Saudi Arabia’s state visit to France, the initiative supports the Kingdom’s Vision 2030 framework to establish localized, sovereign high-performance computing (HPC) and artificial intelligence infrastructure. Operational MetricJoint Venture DetailJoint Venture NamePasqal ArabiaBoard ChairmanshipHRH Prince Abdulaziz Bin Turki Bin Talal (Founder, Eleven Ventures)Corporate PartnersPasqal & Eleven VenturesDeployment FootprintKingdom of Saudi Arabia & MENA regionPrimary FocusOn-premises neutral-atom QPU deployment, AI convergence, and local talent developmentNasdaq SPAC PartnerBleichroeder Acquisition Corp. II (Nasdaq: BBCQ) On-Premises Infrastructure and Regional Workforce Scaling The joint venture establishes a commercial conduit to deploy multiple on-premises quantum computing systems directly within Saudi Arabia rather than relying solely on remote cloud access: Sovereign High-Performance Computing: Pasqal Arabia will integrate neutral-atom quantum hardware alongside high-performance classical computing and AI infrastructure to meet regional enterprise and government demand. Local Capability & Talent Pipeline: The entity will build dedicated technical expertise and workforce development programs within the Kingdom, training domestic quantum engineers and researchers to operate native installations. Diplomatic & Strategic Alignment: The agreement was highlighted during a diplomatic delegation visit by Saudi Arabian officials to Pasqal’s headquarters and QPU manufacturing fac

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Granthi: Higher-Order Quantum Programming via Unitary Wiringquantum-computing

Granthi: Higher-Order Quantum Programming via Unitary Wiring

--> Quantum Physics arXiv:2608.20443 (quant-ph) [Submitted on 20 Aug 2026] Title:Granthi: Higher-Order Quantum Programming via Unitary Wiring Authors:Samson Abramsky, Radha Jagadeesan View a PDF of the paper titled Granthi: Higher-Order Quantum Programming via Unitary Wiring, by Samson Abramsky and Radha Jagadeesan View PDF HTML (experimental) Abstract:Existing quantum programming languages confine higher order structure to a classical host while restricting the quantum layer to first order operations on qubits. This paper presents Granthi, a purely unitary higher-order quantum programming language built on three design commitments: quantum programs are first class values that may be passed, returned, and coherently composed; additive structure is tag-preserving routing rather than observational branching, so control may remain in superposition; and programmer-facing finite label types with named reversible operations provide domain-level control spaces without exposing tag management. Every well-typed term, including at function type, denotes a unitary on its boundary interface, and the compiler realizes exactly its wiring as a quantum circuit on the physical qubit layout (assuming correctness of the pytket backend). Granthi is implemented end-to-end: an OCaml DSL elaborates surface programs through a binder-free core IR to executable quantum circuits via pytket. The language directly supports the quantum switch, compiled to a static circuit, as well as interference on control-flow history and structured finite control, all within the purely unitary fragment. Comments: Subjects: Quantum Physics (quant-ph); Emerging Technologies (cs.ET); Logic in Computer Science (cs.LO); Programming Languages (cs.PL) Cite as: arXiv:2608.20443 [quant-ph]   (or arXiv:2608.20443v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2608.20443 Focus to learn more arXiv-issued DOI via DataCite Submission history From: Radha Jagadeesan [view email] [v1] Thu, 20 Aug 20

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Practical Error Suppression and Mitigation for Reliable Quantum Computingquantum-computing

Practical Error Suppression and Mitigation for Reliable Quantum Computing

--> Quantum Physics arXiv:2608.20453 (quant-ph) [Submitted on 20 Aug 2026] Title:Practical Error Suppression and Mitigation for Reliable Quantum Computing Authors:Han-Ze Li, Mengjie Yang, Xianquan Yan, Dax Enshan Koh, Ching Hua Lee, Ruizhe Shen View a PDF of the paper titled Practical Error Suppression and Mitigation for Reliable Quantum Computing, by Han-Ze Li and 5 other authors View PDF HTML (experimental) Abstract:Quantum computing is entering a transitional regime between noisy intermediate-scale quantum (NISQ) processing and early fault-tolerant quantum computation (FTQC), in which increasingly capable hardware is beginning to support repeated syndrome measurements, partial error correction, and logical-qubit operations, while residual physical and logical errors remain non-negligible. In this regime, error suppression, error mitigation, and quantum error correction are increasingly better viewed as complementary layers of a unified error-reduction strategy rather than as separate approaches, with each acting at a different stage of the quantum computation to improve simulation reliability. Thus, in this review, we provide a practical and forward-looking overview of the principal hardware error sources and the corresponding error suppression and mitigation methods for reducing their impact across the current NISQ-FTQC transition. We discuss hardware-aware circuit design, coherent-error suppression, readout mitigation, noise extrapolation, classical inference, and software-supported workflows, with particular emphasis on their implementation on actual quantum processors. We further examine how error mitigation techniques can be adapted to encoded and logical-qubit settings so that they can operate alongside quantum error correction to suppress residual logical errors and improve the accuracy of computation in the early fault-tolerant regime. Comments: Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2608.20453 [quant-ph]   (or arXiv:2608.20453v1 [quant-

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To Scale Up or To Scale Out: Evaluating Space-Time Costs of Compiled Logical Circuits on Modular Superconducting Quantum Processorsquantum-computing

To Scale Up or To Scale Out: Evaluating Space-Time Costs of Compiled Logical Circuits on Modular Superconducting Quantum Processors

--> Quantum Physics arXiv:2608.20462 (quant-ph) [Submitted on 20 Aug 2026] Title:To Scale Up or To Scale Out: Evaluating Space-Time Costs of Compiled Logical Circuits on Modular Superconducting Quantum Processors Authors:Nikiforos Paraskevopoulos, Sebastian de Bone, Mick Christophersen, Simon Storz, A. Mert Bozkurt, Arno Bargerbos, Sebastian Feld View a PDF of the paper titled To Scale Up or To Scale Out: Evaluating Space-Time Costs of Compiled Logical Circuits on Modular Superconducting Quantum Processors, by Nikiforos Paraskevopoulos and 6 other authors View PDF HTML (experimental) Abstract:Modular integration has emerged as the main pathway for scaling superconducting quantum processing units (QPUs) beyond the constraints of fabrication yield and physical footprint. Currently, two primary strategies lead this effort. Mirroring the "Scaling Up" and "Scaling Out" approaches in GPU architectures and AI infrastructures, these are: chiplet-based scaling, which preserves dense connectivity and high gate fidelity at the expense of engineering complexity, and distributed architectures, which decouple system scaling from monolithic QPU advancements at the expense of sparser connectivity and lower interconnect quality. To evaluate these approaches, we introduce a quantitative stress test measuring the execution cost of a dense workload of random logical entangling operations using a surface code scheme. Using a dedicated compiler, we compute the space-time cost as the number of network nodes increases, analysing this scaling behaviour across various surface code distances, Bell-state fidelities, and Bell-pair generation times. We find that distributed architectures incur an up to exponential space-time performance penalty compared to an effectively monolithic architecture across all simulations. Our results also show that as the network grows, this penalty manifests in two distinct scaling regimes: a noise-dominated regime constrained by insufficient Bell-state fidelity an

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Energetics in daemonic work extraction protocols via non-ideal QND-energy measurementquantum-computing

Energetics in daemonic work extraction protocols via non-ideal QND-energy measurement

--> Quantum Physics arXiv:2608.20487 (quant-ph) [Submitted on 20 Aug 2026] Title:Energetics in daemonic work extraction protocols via non-ideal QND-energy measurement Authors:Daniele Morrone, Francesco Albarelli, Vittorio Giovannetti, Mauro Paternostro, Marco G. Genoni View a PDF of the paper titled Energetics in daemonic work extraction protocols via non-ideal QND-energy measurement, by Daniele Morrone and 3 other authors View PDF HTML (experimental) Abstract:We address the problem of extracting work from a quantum system assisted by a quantum non-demolition (QND) energy measurement. When a perfect QND measurement can be performed and an auxiliary zero-temperature bath is available, the full energy of the quantum state can in principle be extracted even without any prior information on the input state. Owing to the presence of a zero-temperature bath, this is achieved at no energetic cost for the measurement process itself. On the contrary, here we consider what happens when the same protocol is implemented in non-ideal scenarios, specifically when the auxiliary bath has a finite temperature. In this case, not only is it impossible to extract the entire energy from the system, but the measurement strategy also acquires a non-zero energetic cost, accounting for both the interaction between system and measurement apparatus, and the corresponding Landauer erasure cost. We quantitatively assess the performance of these work-extraction protocols, both in absolute terms and through the so-called daemonic net gain, which explicitly includes the energetic cost of the measurement. We rigorously prove that, when access to a thermal bath is allowed in the extraction protocol, the daemonic net gain is always non-positive for any temperature of the auxiliary bath. Conversely, when only unitary operations are considered, the daemonic net gain can attain positive values. We further discuss these different figures of merit by analyzing a paradigmatic example for a single qubit sys

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Clifford-efficient sparse state preparation for molecular wavefunctionsquantum-computing

Clifford-efficient sparse state preparation for molecular wavefunctions

--> Quantum Physics arXiv:2608.20593 (quant-ph) [Submitted on 20 Aug 2026] Title:Clifford-efficient sparse state preparation for molecular wavefunctions Authors:Yingrong Chen, Nathan A. Baker, Rushi Gong, Conrad S.N. Johnston, Brad Lackey, Hongbin Liu, Sasha Schmidt, Yuan Su, David B. Williams-Young, Yinuo Yang View a PDF of the paper titled Clifford-efficient sparse state preparation for molecular wavefunctions, by Yingrong Chen and 8 other authors View PDF HTML (experimental) Abstract:Sparse quantum state preparation concerns an $n$-qubit target state that is a superposition of only $d \ll 2^n$ computational basis states. Existing approaches exploit this sparsity by compressing these $d$ basis states and their amplitudes onto a smaller set of qubits, called the dense register, before expanding the prepared state to the full register. Rather than relying on the permutation-based compression used in prior work, we exploit affine relationships among the binary configurations over the finite field $\operatorname{GF}(2)$ to reduce both the non-Clifford gate count and the ancillary qubit count. Invertible affine transformations over $\operatorname{GF}(2)$, comprising Gaussian elimination and all-ones-row removal, first reduce the dense register from $n$ to the rank $r$ using only Clifford gates and no ancillary qubits. An optional binary encoding stage then trades additional Toffoli gates and ancillary qubits for further compression to the minimum $\lceil\log_2 d\rceil$ dense qubits needed to represent $d$ distinct configurations. For chemically relevant wavefunctions, such as those obtained from selected configuration interaction calculations, shared electronic excitation patterns produce many of these affine relationships, enabling substantial Clifford-only compression before binary encoding. Across the molecular benchmarks, our method requires the fewest ancillary qubits among the evaluated sparse state preparation methods while maintaining comparable non-Clifford ga

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Quantum Zeno and Anti-Zeno Responses: Universal Spectral Criterion for Measurement-Induced Decayquantum-computing

Quantum Zeno and Anti-Zeno Responses: Universal Spectral Criterion for Measurement-Induced Decay

--> Quantum Physics arXiv:2608.20702 (quant-ph) [Submitted on 21 Aug 2026] Title:Quantum Zeno and Anti-Zeno Responses: Universal Spectral Criterion for Measurement-Induced Decay Authors:Yu-Xiang Chen, Yuan-De Jin, Wen-Long Ma View a PDF of the paper titled Quantum Zeno and Anti-Zeno Responses: Universal Spectral Criterion for Measurement-Induced Decay, by Yu-Xiang Chen and 2 other authors View PDF HTML (experimental) Abstract:We develop a general framework for characterizing the response of an evolving quantum system to repetitive quantum measurements. Modeling each evolution-measurement cycle as a quantum channel induced by an effective Liouvillian generator, we find that the Liouvillian spectral gap determines the measurement-induced decay rate. We analyze how the spectral gap responds to the measurement frequency, and define a quantum Zeno response as a decrease in the gap with increasing measurement frequency, and an anti-Zeno response as the opposite. We illustrate this criterion for both discrete-time and continuous-time quantum measurements. In an exactly solvable discrete-time qubit model, the exceptional-point spectral coalescence or spectral crossings mark the transition between Zeno and anti-Zeno responses, which can be experimentally distinguished from the long-time decay envelope of the survival probability. In a continuous-time superconducting-qubit defect model, the same transition manifests as smooth extrema of the spectral gap. Our results establish a universal spectral criterion for measurement-induced decay, offering a practical route to identify and manipulate these effects in generic quantum systems. Comments: Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2608.20702 [quant-ph]   (or arXiv:2608.20702v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2608.20702 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Submission history From: Yuxiang Chen [view email] [v1] Fri, 21 Aug 2026 03:18:28 UTC

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Hybrid dynamical decoupling and coherent driving for high-fidelity nuclear-spin control in diamondquantum-computing

Hybrid dynamical decoupling and coherent driving for high-fidelity nuclear-spin control in diamond

--> Quantum Physics arXiv:2608.20742 (quant-ph) [Submitted on 21 Aug 2026] Title:Hybrid dynamical decoupling and coherent driving for high-fidelity nuclear-spin control in diamond Authors:Jiwon Jeon, Donghun Jung, Eunsang Lee, Junghyun Lee View a PDF of the paper titled Hybrid dynamical decoupling and coherent driving for high-fidelity nuclear-spin control in diamond, by Jiwon Jeon and 3 other authors View PDF Abstract:Nitrogen-vacancy (NV) centers in diamond provide room-temperature electron-nuclear spin registers for quantum sensing and quantum information processing, with surrounding 13C nuclear spins serving as long-lived quantum memories. However, coherent control of large nuclear-spin registers is limited by finite electron-spin coherence and spectral addressability. Existing approaches follow two complementary strategies: dynamical-decoupling (DD) gates exploit filter-function resonances to realize selective conditional evolution but permit only discrete rotation angles, whereas dynamical-decoupling radio-frequency (DDrf) control restores continuous tunability at the cost of stringent hyperfine-geometry and RF-power requirements. Here, we introduce hybrid dynamical-decoupling and radio-frequency (H-DDrf) control, which preserves the DD-induced conditional evolution and employs a geometrically phase-matched RF drive to complete the target operation. This approach reduces both RF power and gate duration while maintaining high-fidelity control, thereby expanding the accessible 13C nuclear-spin register for room-temperature NV-based quantum memories and quantum processors. Comments: Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2608.20742 [quant-ph]   (or arXiv:2608.20742v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2608.20742 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Submission history From: Jiwon Jeon [view email] [v1] Fri, 21 Aug 2026 05:02:26 UTC (15,779 KB) Full-text links: Access Paper: View

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The four-dimensional Chamon codequantum-computing

The four-dimensional Chamon code

--> Quantum Physics arXiv:2608.20775 (quant-ph) [Submitted on 21 Aug 2026] Title:The four-dimensional Chamon code Authors:Zhipeng Liang, Xuan Wang View a PDF of the paper titled The four-dimensional Chamon code, by Zhipeng Liang and Xuan Wang View PDF HTML (experimental) Abstract:Fracton models have attracted considerable interest as candidates for quantum memories because of their unconventional ground-state degeneracy (GSD) and restricted-mobility excitations. The four-dimensional (4D) Chamon code introduced in our previous work is constructed via the 4D XYZ product of two two-dimensional (2D) toric codes. Its GSD grows exponentially with the system size, similar to that of the three-dimensional (3D) Chamon code, suggesting that it may be regarded as a 4D generalization of the 3D Chamon code. However, the excitation properties of the 4D Chamon code have not been studied in depth, and a high-performance decoding strategy is still lacking. In this work, we first establish the correspondence between the algebraic structure of the 4D Chamon code and the 4D lattice, thereby characterizing the geometric distributions of qubits and stabilizers. Second, we show that the 4D Chamon code supports three types of restricted-mobility excitations analogous to those of the 3D Chamon code, further supporting its interpretation as a 4D generalization of the 3D Chamon code. Finally, we uncover two structural properties relevant to decoding: a hyperplane symmetry and a projection-induced 2D toric-code structure. By exploiting these properties, we develop a two-layer decoding strategy that decomposes the original decoding problem into multiple independent and parallelizable subproblems. Numerical simulations show that the proposed decoder substantially outperforms BP-OSD in decoding accuracy, demonstrating the benefit of incorporating the intrinsic geometric and algebraic structures of the code into decoder design. Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2608.20775 [quant-

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