Quantum News
Sign InSign Up
Home/Quantum Technology/Quantum Error Correction: Surface Code & Fault-Tolerant Computing

Quantum Error Correction: Surface Code & Fault-Tolerant Computing

Quantum error correction news: logical qubits, surface code, fault-tolerant quantum computing, QEC. Error mitigation & suppression.

9,002 Articles
Updated Daily

Quantum error correction (QEC) is the critical enabler for fault-tolerant quantum computing, protecting quantum information from environmental noise through redundant encoding across multiple physical qubits. Recent breakthroughs demonstrated below-threshold error correction where logical qubit error rates fall below physical qubit rates.

The 2D surface code is the leading QEC approach due to high error threshold (~1%), local nearest-neighbor interactions, and compatibility with superconducting chip designs. Recent breakthroughs include Google's Willow demonstrating below-threshold surface code scaling, and IBM's Heavy Hex optimizing qubit connectivity for surface code implementation.

India's Quantum Error Correction Research

India's National Quantum Mission includes quantum error correction in its basic science research component. The Foundation for QC Innovation at IISc Bengaluru addresses error correction as part of its quantum computing development. The Harish-Chandra Research Institute (HRI) and Institute of Mathematical Sciences (IMSc) conduct theoretical research on quantum error correction codes.

The NQM targets developing intermediate-scale quantum computers with 50-1000 physical qubits, requiring error mitigation and eventually error correction to achieve quantum advantage. The mission includes development of indigenous control electronics and error mitigation techniques.

Researchers harness sunlight to generate quantum entanglementquantum-computing

Researchers harness sunlight to generate quantum entanglement

Concentrating sunlight A new solar concentrator uses sunlight to produce pairs of entangled photons. (Courtesy: Florian Sterl and Soledad Cook)"> Concentrating sunlight A new solar concentrator uses sunlight to produce pairs of entangled photons. (Courtesy: Florian Sterl and Soledad Cook) As the world of quantum computing grows and researchers work towards scaling up quantum systems, energy consumption is becoming a major concern. Beyond the small scale and high level of control in a laboratory environment, the lasers that power quantum systems result in a large energy cost that may act as a bottleneck for the integration of quantum technology. Publishing their findings in Optica, researchers have demonstrated that sunlight can be used to generate pairs of entangled photons, providing a more energy efficient alternative to laser-pumped systems. This collaborative project combined theoretical research led by Robert Boyd at the University of Ottawa with technology developed by Hanieh Fattahi’s research group at the Max Plank Institute for the Science of Light in Erlangen, Germany. Overcoming assumptions Optical quantum computers use pairs of entangled photons as qubits, with the nonlinear optical processes used to produce them typically relying on lasers. This is largely due to two assumptions: firstly, that high optical coherence is required, meaning that the light waves maintain a steady phase relationship; and secondly, that lasers are the only way to achieve the necessary optical power density for these methods. Sunlight, while naturally abundant, is largely incoherent and is difficult to collect in concentrations comparable to that of lasers. As such, this natural reservoir of optical input has been largely overlooked as a direct resource for nonlinear optical processes. The researchers behind this latest study are challenging these assumptions with a new system that uses sunlight to fuel a process called spontaneous parametric down-conversion (SPDC). In this pro

Physics World QuantumLoading...0
Arqit Quantum: The Little Boat That Couldn'tquantum-computing

Arqit Quantum: The Little Boat That Couldn't

Luis Cortes Dequidt1 FollowerFollowSummaryArqit Quantum trades at a premium 397.6x FY26 EV/Sales, despite fundamentals not justifying its valuation versus peers.ARQQ faces significant risks: imminent 5.44M share dilution, stagnant R&D, ineffective cost controls, and recurring revenue uncertainty.My base case price target is $16.66 (-21.1%), reflecting warranted multiple compression, dilution, and ongoing cash burn pressures.ARQQ's product and execution lag behind competitors, raising concerns about its ability to capitalize on the quantum cryptography opportunity.Editor's note: Seeking Alpha is proud to welcome Luis Cortes Dequidt as a new contributing analyst. You can become one too! Share your best investment idea by submitting your article for review to our editors. Get published, earn money, and unlock exclusive SA Premium access. This article was written byLuis Cortes Dequidt1 FollowerFollowLuis Cortes Dequidt is a CFA charterholder and MBA graduate with a background spanning hedge fund equity research, financial modeling consulting, and wealth management. He most recently served as an Equity Analyst at Grow Funds LLC, a fundamental small-cap long/short equity hedge fund and 26-time Barclay Hedge Top 10 award recipient, where he initiated coverage of the quantum computing sector (RGTI, IONQ, QBTS, QNT), built financial models from scratch (DCF, SOTP, multiples-based, and comparable company analyses), and generated long and short investment ideas across global small-cap names. Before Grow Funds, Luis worked as a Financial Modeling Specialist at The Beyster Institute, where he built three-statement models and conducted valuation and due diligence work for middle-market clients. He began his career at UBS as a Registered Client Service Associate in the capacity of a financial analyst and assistant portfolio manager a financial advisor team managing over $200M in AUM, where he built a Python-based quantitative screening model to rank funds and ETFs across perfo

Seeking AlphaLoading...0
On the Reachability Problem in Quantum Petri Netsquantum-computing

On the Reachability Problem in Quantum Petri Nets

--> Quantum Physics arXiv:2608.21428 (quant-ph) [Submitted on 16 Aug 2026] Title:On the Reachability Problem in Quantum Petri Nets Authors:Syed Asad Shah, A. Yavuz Oruc View a PDF of the paper titled On the Reachability Problem in Quantum Petri Nets, by Syed Asad Shah and A. Yavuz Oruc View PDF HTML (experimental) Abstract:In this paper, we propose a novel quantum solution to address the problem of reachability in bounded quantum Petri nets (QPNs), an advanced modeling framework that combines the classical Petri net model with quantum mechanical principles. The proposed approach exploits quantum parallelism to construct a superposition over all reachable markings from the initial marking. Grover's amplitude amplification algorithm is then applied to efficiently identify a desired target marking, while ancillary q-tokens used solely for transition control are excluded from the search space, significantly reducing its size. Theoretical analysis shows that our approach achieves a quadratic speed up over classical exhaustive algorithms. Experimental results also confirm the correctness and feasibility of the proposed quantum algorithm for solving the bounded reachability problem in Quantum Petri Nets. Comments: Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2608.21428 [quant-ph]   (or arXiv:2608.21428v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2608.21428 Focus to learn more arXiv-issued DOI via DataCite Submission history From: A. Yavuz Oruc [view email] [v1] Sun, 16 Aug 2026 21:36:59 UTC (644 KB) Full-text links: Access Paper: View a PDF of the paper titled On the Reachability Problem in Quantum Petri Nets, by Syed Asad Shah and A. Yavuz OrucView PDFHTML (experimental)TeX Source view license Current browse context: quant-ph < prev   |   next > new | recent | 2026-08 References & Citations INSPIRE HEP NASA ADSGoogle Scholar Semantic Scholar export BibTeX citation Loading... BibTeX formatted citation × loa

arXiv Quantum PhysicsLoading...0
The Pauli Probability Spectrum Carries the Pure-State Quantum Fisher Metricquantum-computing

The Pauli Probability Spectrum Carries the Pure-State Quantum Fisher Metric

--> Quantum Physics arXiv:2608.21437 (quant-ph) [Submitted on 17 Aug 2026] Title:The Pauli Probability Spectrum Carries the Pure-State Quantum Fisher Metric Authors:E. A. Ramirez Trino, M. A. Rajabpour View a PDF of the paper titled The Pauli Probability Spectrum Carries the Pure-State Quantum Fisher Metric, by E. A. Ramirez Trino and M. A. Rajabpour View PDF HTML (experimental) Abstract:Stabilizer Rényi entropies compress the distribution of squared Pauli expectation values of a pure quantum state into scalar measures of nonstabilizerness. Here we show that, before this compression, the distribution has a remarkably simple information-geometric structure. For any smooth pure-state family of $N$ qubits, its classical Fisher information matrix is exactly twice the quantum Fisher information matrix of the state at every regular point. This information can be accessed directly: by preparing the state together with its complex conjugate and performing pairwise Bell measurements between corresponding qubits, one samples the same Pauli distribution and saturates the quantum Fisher information matrix of the conjugate pair. The readout is fixed and does not depend on the number of estimated parameters or on the particular pure-state sensing model. We show that the origin of this result is more general than Pauli algebra: conjugation identifies the doubled pure state with the vectorized density operator, whose coordinates are real in any Hermitian Hilbert--Schmidt operator basis. The situation changes for mixed states, for which the Bell probabilities no longer coincide with normalized squared Pauli expectation values and the same fixed readout is generally not optimal. We derive an exact positive-semidefinite expression for the missing Fisher information, identifying the components of the state variation that are invisible to Bell sampling. Our results reveal a direct connection between stabilizer Rényi statistics, quantum-state geometry, and fixed multiparameter readout. C

arXiv Quantum PhysicsLoading...0
Robust cavity metrology beyond the limits of Pound-Drever-Hallquantum-computing

Robust cavity metrology beyond the limits of Pound-Drever-Hall

--> Quantum Physics arXiv:2608.21512 (quant-ph) [Submitted on 21 Aug 2026] Title:Robust cavity metrology beyond the limits of Pound-Drever-Hall Authors:Ibukunoluwa Adisa, Won Chan Lee, Yanqin Huang, Nathan Schine, Kevin C. Cox, Alicia J. Kollár View a PDF of the paper titled Robust cavity metrology beyond the limits of Pound-Drever-Hall, by Ibukunoluwa Adisa and 5 other authors View PDF HTML (experimental) Abstract:Precise measurement of the resonance frequencies of microwave and optical cavities is a foundational capability across quantum technologies. One of the highest-performance methods currently available is Pound-Drever-Hall (PDH) spectroscopy, which relies on a three-tone interrogation and eliminates sensitivity to path-length fluctuations. However, PDH is known to suffer from systematic offsets due to residual amplitude modulation and demodulation-phase errors. Here we leverage an optimal linear combination of the phases of the three interrogation tones to implement a method for robust cavity metrology which eliminates significant systematic-error sensitivities of PDH. We experimentally demonstrate robust cavity measurements in both the optical and microwave frequency regime, showing insensitivity to sideband imbalance and demodulation phase, as well as demonstrating single-shot readout of a cavity-coupled superconducting qubit. Comments: Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2608.21512 [quant-ph]   (or arXiv:2608.21512v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2608.21512 Focus to learn more arXiv-issued DOI via DataCite Submission history From: Ibukunoluwa Adisa [view email] [v1] Fri, 21 Aug 2026 18:00:01 UTC (1,317 KB) Full-text links: Access Paper: View a PDF of the paper titled Robust cavity metrology beyond the limits of Pound-Drever-Hall, by Ibukunoluwa Adisa and 5 other authorsView PDFHTML (experimental)TeX Source view license Current browse context: quant-ph < prev   |   next >

arXiv Quantum PhysicsLoading...0
Asymptotic entanglement in circle stabilizer states and states forbidding arbitrary vertex-minorsquantum-computing

Asymptotic entanglement in circle stabilizer states and states forbidding arbitrary vertex-minors

--> Quantum Physics arXiv:2608.21526 (quant-ph) [Submitted on 21 Aug 2026] Title:Asymptotic entanglement in circle stabilizer states and states forbidding arbitrary vertex-minors Authors:Kenneth Goodenough, Marcelo Sales View a PDF of the paper titled Asymptotic entanglement in circle stabilizer states and states forbidding arbitrary vertex-minors, by Kenneth Goodenough and 1 other authors View PDF HTML (experimental) Abstract:Stabilizer states play a central role in quantum information theory, and understanding their entanglement has motivated a large body of work. A well-studied question in particular is when a stabilizer state $|\psi\rangle$ can be transformed into another stabilizer state $|\phi\rangle$ using only single-qubit Clifford operations and Pauli measurements. If this is possible, we say that $|\phi\rangle$ is a vertex-minor of $|\psi\rangle$. Assuming Geelen's weak structural conjecture on vertex-minors, we establish the following general statement. For any fixed stabilizer state $|\phi\rangle$, the entanglement in stabilizer states $|\psi\rangle$ that do not contain $|\phi\rangle$ as a vertex-minor is asymptotically constrained. More concretely, we show that the distance of any sufficiently rank-connected $|\psi\rangle$ not containing $|\phi\rangle$ as a vertex-minor grows as $O(\log n)$, and prove similar results for the so-called locally accessible information, a quantity that captures the amount of information that can be learned through single-qubit Pauli measurements. Our results rely on (i) connecting the above two entanglement measures to rank functions of multimatroids, (ii) connecting the rank functions of circle stabilizer states to rank functions on $4$-regular multigraphs, which asymptotically constrains the entanglement of circle stabilizer states, and (iii) using Geelen's weak structural conjecture on vertex-minors to `lift' the previous result to sufficiently connected states in proper vertex-minor-closed families of stabilizer states.

arXiv Quantum PhysicsLoading...0
Prior-Informed Adaptive Shifts for Sequential Minimal Optimization in Variational Quantum Eigensolversquantum-computing

Prior-Informed Adaptive Shifts for Sequential Minimal Optimization in Variational Quantum Eigensolvers

--> Quantum Physics arXiv:2608.21616 (quant-ph) [Submitted on 21 Aug 2026] Title:Prior-Informed Adaptive Shifts for Sequential Minimal Optimization in Variational Quantum Eigensolvers Authors:Frederik Stalschus, Samuele Pedrielli, Stefan Kühn, Karl Jansen, Kim A. Nicoli, Shinichi Nakajima View a PDF of the paper titled Prior-Informed Adaptive Shifts for Sequential Minimal Optimization in Variational Quantum Eigensolvers, by Frederik Stalschus and 5 other authors View PDF HTML (experimental) Abstract:Sequential minimal optimization methods, such as the Rotosolve and the Nakanishi-Fujii-Todo algorithm (NFT), are widely used for Variational Quantum Eigensolvers (VQEs). These methods optimize one parameter direction at a time, requiring measurements at only a few locations along that direction. In the presence of measurement shot noise, however, their performance depends critically on the choice of measurement locations, and recent studies suggest that equidistant measurements are optimal. However, we often observe that equidistant measurements are not always optimal in practice. We argue that this discrepancy between theory and practice arises from the fact that two assumptions underlying previous analyses do not generally hold: (1) the absence of prior knowledge about the energy minimizer, and (2) the use of the uncertainty of the estimated energy as a proxy for optimization performance. In this paper, we develop a new theory for determining optimal measurement locations. First, we show that incorporating prior information about the minimizer is beneficial. Early in optimization, when little is known about the pivot, i.e., the current minimizer, equidistant measurements are indeed near-optimal, but as the prior belief sharpens the optimal locations move away from equidistant. Second, rather than analyzing the uncertainty of the estimated minimum energy, we study the uncertainty of the estimator of the minimizer itself, which leads to substantially different strategies

arXiv Quantum PhysicsLoading...0
Measurement and reload costs in direct quantum simulation of nonlinear wavesquantum-computing

Measurement and reload costs in direct quantum simulation of nonlinear waves

--> Quantum Physics arXiv:2608.21647 (quant-ph) [Submitted on 21 Aug 2026] Title:Measurement and reload costs in direct quantum simulation of nonlinear waves Authors:Ziqing Guo, Viraj Dsouza, Alex Khan, Abhishek Chopra, Rut Lineswala, Ziwen Pan View a PDF of the paper titled Measurement and reload costs in direct quantum simulation of nonlinear waves, by Ziqing Guo and 5 other authors View PDF HTML (experimental) Abstract:Quantum processors encode an N-point field in log_2(N) qubits, which renders nonlinear wave equations an important application for quantum simulation. Nonlinear evolution, however, requires the field values themselves, and these are not directly accessible without quantum measurement. Existing algorithms circumvent this measurement through linear embeddings and state copies, thereby obscuring its cost within the truncation order, the auxiliary dimensions, and the state preparation. In order to expose this cost, a hybrid split-step solver is proposed in which the field is measured, updated classically, and reloaded at every step, with all shots and gates accounted for in a single cost-and-error model. Since the entire field is available at every step, a property unavailable to linear approximations in strongly nonlinear regimes, the design of the solver reduces to a budgeting problem over the timestep, the polynomial degree, and the shot count. The coherent kernels of the solver are validated on superconducting hardware. An identical structure and bottleneck govern the viscous Burgers' equation in one and two dimensions. Because every step reads the full field, the quantum cost per step, measured as circuit depth multiplied by measurement shots, exceeds the classical cost with increasing grid size. The framework consequently identifies a coherent, measurement-free nonlinear update as the quantitative target that any end-to-end advantage must meet. Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2608.21647 [quant-ph]   (or arXiv:2608.21647v1

arXiv Quantum PhysicsLoading...0
Scalable Quantum Key Distribution via GHZ Entanglement and Qubit Reusequantum-computing

Scalable Quantum Key Distribution via GHZ Entanglement and Qubit Reuse

--> Quantum Physics arXiv:2608.21667 (quant-ph) [Submitted on 21 Aug 2026] Title:Scalable Quantum Key Distribution via GHZ Entanglement and Qubit Reuse Authors:Tasdiqul Islam, Rasman Mubtasim Swargo, Engin Arslan, Md Arifuzzaman View a PDF of the paper titled Scalable Quantum Key Distribution via GHZ Entanglement and Qubit Reuse, by Tasdiqul Islam and 2 other authors View PDF Abstract:Conventional Quantum Key Distribution (QKD) requires the transmission of qubits proportional to or exceeding the length of the key, as protocols such as BB84 transmit more qubits than the final key size due to basis sifting and privacy amplification. Since quantum networks are still in their infancy and have limited capacity, this overhead puts significant pressure on network resources. To address this issue, we propose a Multi-Qubit Greenberger--Horne--Zeilinger (GHZ) State-based QKD scheme that reduces the number of qubits transmitted over the quantum channel. The proposed method transmits one GHZ qubit between endpoints and reuses the resulting entanglement to convey multiple classical key bits with the help of Quantum Non-Demolition (QND) measurements. Under the stated assumptions on authenticated classical communication, local reset verification, and bounded-error QND discrimination, one can transfer $L$ classical bits by generating an (L+1)-qubit GHZ state and transferring one qubit to the remote party. We verify correctness using the NetSquid quantum network simulator: the protocol achieves 100\% raw-key fidelity for keys of length up to 12 bits under both ideal conditions and depolarizing noise up to p = 0.005 per round. We further show that the proposed QKD algorithm can be extended to multi-party QKD and server-client deployment. The proposed scheme offers a transmitted-qubit-efficient, noise-tolerant alternative for bandwidth-limited quantum networks. Comments: Subjects: Quantum Physics (quant-ph); Cryptography and Security (cs.CR); Networking and Internet Architecture (cs.N

arXiv Quantum PhysicsLoading...0
Scalable quantum simulation of continuous-time generative models via tensor networksquantum-computing

Scalable quantum simulation of continuous-time generative models via tensor networks

--> Quantum Physics arXiv:2608.21700 (quant-ph) [Submitted on 22 Aug 2026] Title:Scalable quantum simulation of continuous-time generative models via tensor networks Authors:Nathan X. Kodama, L. Andrew Wray, Sam Cochran, Chad Rigetti, Shravan Veerapaneni, Michael J. Keiser View a PDF of the paper titled Scalable quantum simulation of continuous-time generative models via tensor networks, by Nathan X. Kodama and 5 other authors View PDF HTML (experimental) Abstract:Continuous-time flow and diffusion models are widely used across many application domains, from large-scale deployment in computer vision and protein folding to emerging adoption for modeling language, time series, and quantum states. After training, inferring statistical properties from continuous-time models is costly. Wavefunction flows target this cost by recasting learned transport as unitary evolution, whose final Born distribution approximates the target distribution. This prepares a coherent amplitude encoding (a qsample) that can be post-processed by quantum algorithms offering a quadratic advantage over Monte Carlo sampling. We present the first numerical study of these flows, in which we represent time-dependent potentials and states as tensor networks. At spatial dimension $d=8$, storage falls by $\sim 10^7\times$ relative to the dense grid of $N^d$ points, and evolution wall-clock time falls by $\gtrsim 10^3\times$ against a baseline extrapolated from the measured $d\le 5$ scaling. We validate our pipeline by reproducing the $O(1/\sqrt{p_{\rm rare}})$ scaling of rare-event sampling. Subjects: Quantum Physics (quant-ph); Artificial Intelligence (cs.AI); Machine Learning (cs.LG) Cite as: arXiv:2608.21700 [quant-ph]   (or arXiv:2608.21700v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2608.21700 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Submission history From: Nathan Kodama [view email] [v1] Sat, 22 Aug 2026 00:24:06 UTC (1,309 KB) Full-t

arXiv Quantum PhysicsLoading...0
Infleqtion’s chip powers Japan’s first full quantum system
Featured
quantum-computing

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

Quantum ZeitgeistLoading...0
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

Quantum ZeitgeistLoading...0
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,

Quantum ZeitgeistLoading...0
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.

The Qubit ReportLoading...0
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

Quantum ZeitgeistLoading...0
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

The Motley FoolLoading...0
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

Quantum ZeitgeistLoading...0
Infleqtion Collaboration with Japan Moonshot Program Achieves Major Milestone: “Shunkai” Neutral Atom Quantum Computer Now Operational
Featured
quantum-computing

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

ColdQuantaLoading...0
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

Quantum ZeitgeistLoading...0
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

Quantum Computing ReportLoading...0

Related Topics

Superconducting QubitsTrapped Ion Quantum ComputingNeutral Atom Quantum ComputingQuantum Software Development