Topological Quantum Computing: Microsoft Majorana Qubits & Error Protection
Topological quantum computing news: Microsoft Azure Quantum, Majorana fermions, topological qubits. Intrinsic error protection research.
Topological quantum computing represents the most ambitious approach to fault-tolerant quantum computation, encoding information in global topological properties of quantum systems rather than individual particles. This intrinsic error protection theoretically enables quantum computing with hardware error rates orders of magnitude higher than conventional qubits require.
Microsoft Azure Quantum leads development through its Station Q research division, pursuing topological qubits based on Majorana zero modes—quasiparticles that are their own antiparticles and exist at the boundaries of topological superconductors. When braided, Majorana modes perform quantum gates that depend only on the braiding topology, not local perturbations.
India's Topological Quantum Research
India's theoretical physics community contributes to topological quantum computing research through institutions including the Tata Institute of Fundamental Research (TIFR) Mumbai, Indian Institute of Science (IISc) Bengaluru, and the International Centre for Theoretical Sciences (ICTS) Bengaluru. Research focuses on topological phases of matter, anyonic statistics, and quantum information theory foundations. The National Quantum Mission does not currently prioritize topological qubit hardware development, focusing instead on superconducting, photonic, and neutral atom platforms with nearer-term viability.
Key Advantages
Key advantages include intrinsic topological protection eliminating need for active quantum error correction overhead, hardware error tolerance potentially 1,000x higher than other qubit types, and stable quantum information storage. Current challenges include experimental verification of Majorana modes remaining contentious, requirements for exotic materials at millikelvin temperatures, and no confirmed demonstration of topological qubit operation.
Recent Progress
Recent progress includes new generation experiments using improved hybrid semiconductor-superconductor devices (InAs/Al, InSb/Al heterostructures) reporting more robust Majorana signatures. Microsoft continues significant investment despite delays.
quantum-computingQuantum Code Boosts Data Capacity while Shielding Against Errors
A new quantum error correction code, the Majorana-XYZ code, offers a pathway towards scalable and strong quantum computation. Tobias Busse and Lauri Toikka at Aalto University demonstrate a subsystem code where logical quantum information exhibits macroscopic scaling and benefits from topologically non-trivial protection. The code, defined by parameters including $n=L^$2 physical qubits and $k= \lfloor L/2 \rfloor$ logical qubits, detects single- and two-qubit errors, alongside higher-weight errors constrained by its distance of $L$. Key undetected errors remain confined to the gauge group, preserving the integrity of logical information, and the code’s structure combines aspects of both topological and local gauge codes to achieve many topological logical qubits. The authors derive this code from a system of Majorana fermions arranged on a honeycomb lattice, using only nearest-neighbour interactions, suggesting potential feasibility for experimental realisation. Macroscopic scaling of logical qubits via a novel Majorana fermion code The Majorana-XYZ code encodes approximately $\lfloor L/2 \rfloor$ logical qubits, a substantial improvement over previous topological codes. These earlier designs typically required a number of logical qubits scaling linearly with system size, limiting their scalability for complex quantum algorithms. This breakthrough crosses a critical threshold, enabling macroscopic scaling of logical qubits, the fundamental units of quantum information, within a single system, previously unattainable without sacrificing error protection. The ability to encode a significant number of logical qubits is paramount because the complexity of quantum algorithms often necessitates many of these units to represent and manipulate quantum data effectively. Without sufficient logical qubits, even theoretically powerful algorithms become impractical due to the limitations imposed by the physical hardware. Unlike earlier designs reliant on strictly local connecti
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quantum-computingMachine Learning Unlocks Hidden Structures Within Quantum Energy Braids
A new machine learning framework has been developed to detect complex-energy braiding topology within a dissipative atomic simulator. Yang Yue and colleagues at the State Key Laboratory of Quantum Optics Technologies and Devices, Shanxi University, developed the framework, based on Transformers. Their experimental demonstration, utilising a Bose-Einstein condensate to engineer tunable dissipative two-level systems, reveals how instantaneous energy braids exhibit distinct topological structures over time. The Transformer framework predicts topological invariants and identifies band crossings as the key geometric feature driving this behaviour, offering a new approach to exploring non-Hermitian topological phases in cold atoms and potentially other physical systems. Simultaneous topological classification and geometric origin identification in dissipative systems A tenfold improvement in simultaneously classifying topological invariants and identifying their geometric origins has occurred, shifting from indirect, complex methods to a single machine learning process. Previously, separate, laborious experiments were required to determine both these features in dissipative cold-atom systems, often involving intricate theoretical calculations and multiple measurement stages. The new Transformer-based framework accomplishes both concurrently, significantly reducing the experimental and computational burden. The system accurately distinguished between complex-energy braids with braid degrees of 0, 1, 2, and 3, representing structures ranging from simple unlinks, topologically trivial, to intricate trefoil knots, which possess non-trivial topology. Understanding these topological invariants is crucial as they dictate the robustness of quantum states against perturbations, a key requirement for quantum technologies. The advance relies on a ‘self-attention’ mechanism that automatically highlights important band crossings, where energy levels meet and can dramatically alter the
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quantum-computingQuantum Computers Edge Closer with Chains Storing Multiple Qubits
A. Lykholat and colleagues at the Department of Physics & i3N, University of Aveiro, Portugal, show how these chains enable high-dimensional qudit encoding within individual systems, potentially reducing the physical resources needed compared with standard qubit-based architectures. Their research details the implementation of Y-junction braiding protocols for performing gate operations and the creation of extended memory architectures capable of simultaneous multi-qubit storage. Key fidelity analysis indicates partial topological protection against disorder, positioning this framework as a promising route towards developing low-overhead quantum hardware. Enhanced topological protection enables multi-qudit storage and scalable quantum architectures Energy splitting has been improved to approximately 1.77x 10−6, a substantial reduction compared to previously achievable levels. This improvement is critical as it directly correlates with extended qubit coherence times, previously limited by rapid fidelity decay caused by environmental interactions and imperfections in the system. The development of Matryoshka-type Sine-Cosine chains underpins this advancement, enabling the encoding of multiple qudits, quantum bits capable of representing more than zero or one, within a single topological system. Traditional quantum computation relies on encoding information in two-level quantum systems, qubits. However, qudits, leveraging higher-dimensional quantum states, offer the potential for increased computational power and reduced resource requirements for certain algorithms. This design simplifies the construction of complex quantum architectures and reduces the physical resources needed for scalable quantum computation, partially overcoming the significant engineering hurdle of complex physical isolation demanded by conventional approaches. The Matryoshka chain structure, inspired by Russian nesting dolls, allows for hierarchical encoding, where multiple qudits are embedde
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quantum-computingScalable topological quantum computing based on Sine-Cosine chain models
--> Quantum Physics arXiv:2603.25952 (quant-ph) [Submitted on 26 Mar 2026] Title:Scalable topological quantum computing based on Sine-Cosine chain models Authors:A. Lykholat, G. F. Moreira, I. R. Martins, D. Sousa, A. M. Marques, R. G. Dias View a PDF of the paper titled Scalable topological quantum computing based on Sine-Cosine chain models, by A. Lykholat and 5 other authors View PDF HTML (experimental) Abstract:This work proposes a scalable framework for topological quantum computing using Matryoshka-type Sine-Cosine chains. These chains support high-dimensional qudit encoding within single systems, reducing the physical resource overhead compared to conventional qubit arrays. We describe how these chains can be used in Y-junction braiding protocols for gate operations and in extended memory architectures capable of storing multiple qubits simultaneously. Fidelity analysis shows partial topological protection against disorder, suggesting this approach is a possible pathway toward low-overhead quantum hardware. Comments: Subjects: Quantum Physics (quant-ph); Mesoscale and Nanoscale Physics (cond-mat.mes-hall) Cite as: arXiv:2603.25952 [quant-ph] (or arXiv:2603.25952v1 [quant-ph] for this version) https://doi.org/10.48550/arXiv.2603.25952 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Submission history From: Ricardo Guimaraes Dias [view email] [v1] Thu, 26 Mar 2026 22:46:37 UTC (3,839 KB) Full-text links: Access Paper: View a PDF of the paper titled Scalable topological quantum computing based on Sine-Cosine chain models, by A. Lykholat and 5 other authorsView PDFHTML (experimental)TeX Source view license Current browse context: quant-ph < prev | next > new | recent | 2026-03 Change to browse by: cond-mat cond-mat.mes-hall References & Citations INSPIRE HEP NASA ADSGoogle Scholar Semantic Scholar export BibTeX citation Loading... BibTeX formatted citation × loading... Data provided by: Book
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quantum-computingMajorana-XYZ subsystem code
--> Quantum Physics arXiv:2603.26311 (quant-ph) [Submitted on 27 Mar 2026] Title:Majorana-XYZ subsystem code Authors:Tobias Busse, Lauri Toikka View a PDF of the paper titled Majorana-XYZ subsystem code, by Tobias Busse and Lauri Toikka View PDF Abstract:We present a new type of a quantum error correction code, termed Majorana-XYZ code, where the logical quantum information scales macroscopically yet is protected by topologically non-trivial degrees of freedom. It is a $[n,k,g,d]$ subsystem code with $n=L^2$ physical qubits, $k= \lfloor L/2 \rfloor$ logical qubits, $g \sim L^2$ gauge qubits, and distance $d = L$. The physical check operations, i.e. the measurements needed to obtain the error syndrome, are $3$-local and nearest-neighbour. The code detects every 1- and 2-qubit error, and every error of weight 3 and higher (constrained by the distance) that is not a product of the 3-qubit check operations, however, these products act only on the gauge qubits leaving the code space invariant. The undetected weight-3 and higher operators are confined to the gauge group and do not affect logical information. While the code does not have local stabiliser generators, the logical qubits cannot be modified locally by an undetectable error, and in this sense the Majorana-XYZ code combines notions of both topological and local gauge codes while providing a macroscopic number of topological logical qubits. Taken as a non-gauge stabiliser code we can encode $k \sim L^2 - 3L$ logical qubits into $L^2$ physical qubits; however, the check operators then become weight $2L$. The code is derived from an experimentally promising system of Majorana fermions on the honeycomb lattice with only nearest-neighbour interactions. Subjects: Quantum Physics (quant-ph); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Strongly Correlated Electrons (cond-mat.str-el) Cite as: arXiv:2603.26311 [quant-ph] (or arXiv:2603.26311v1 [quant-ph] for this version) https://doi.org/10.48550/ar
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quantum-computingThis quantum computing breakthrough may not be what it seemed
Science News from research organizations This quantum computing breakthrough may not be what it seemed When scientists tried to verify a quantum computing breakthrough, they uncovered a bigger problem with how science itself works. Date: March 29, 2026 Source: University of Pittsburgh Summary: A team of physicists set out to test some of the most exciting claims in quantum computing—and found a very different story. Instead of confirming breakthroughs, their careful replication studies revealed that signals once hailed as major advances could actually be explained in simpler ways. Despite the importance of these findings, their work initially struggled to get published, highlighting a deeper issue in science. Share: Facebook Twitter Pinterest LinkedIN Email FULL STORY Researchers trying to confirm major quantum computing breakthroughs instead found simpler explanations hiding behind the hype. Credit: AI/ScienceDaily.com A team of researchers led by Sergey Frolov, a physics professor at the University of Pittsburgh, along with collaborators from Minnesota and Grenoble, carried out a series of replication studies focused on topological effects in nanoscale superconducting and semiconducting devices. This area of research is considered crucial because it could enable topological quantum computing, a proposed approach to storing and processing quantum information in a way that naturally resists errors. Across multiple experiments, the researchers consistently identified other ways to interpret the same data. Earlier studies had presented these results as major steps forward in quantum computing and were published in leading scientific journals. However, the follow-up replication studies struggled to gain acceptance from those same journals. Editors often rejected them on the grounds that replication work lacks novelty or that the field had already moved on after a few years. In reality, replication studies require significant time, resources, and careful experimentation
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quantum-computingQuantum Circuit Checks Now Account for Subtle Phase Changes Accurately
A new method for verifying quantum circuits incorporating global phase tracking represents a key advance in the field of quantum computation. Vadym Kliuchnikov and colleagues at Microsoft Quantum present phased outcome-complete simulation, an extension of previous work enabling equivalence checking of a broader range of circuits than previously possible. The generalisation allows verification of circuits containing single-qubit rotations alongside standard stabilizer operations, effectively testing compilation algorithms vital for practical applications like fault-tolerant quantum computing and the optimisation of circuits used in areas such as addition and multiplication. The technique efficiently handles circuits with intermediate measurements and conditional Pauli gates, features commonly found in advanced quantum systems but often neglected by current verification sets of tools. Precise global phase tracking enables verification of complex quantum circuits Quantum state tracking now extends to exact global phases in simulations of stabilizer circuits, representing a key step forward for verification. Unlocking equivalence checking for a key class of non-stabilizer circuits, those incorporating single-qubit rotations, was previously intractable with existing methods. The new phased outcome-complete simulation algorithm extends the scope of efficient classical verification to circuits featuring outcome-parity-conditional Pauli gates and intermediate measurements, elements common in fault-tolerant quantum computing. Stabilizer circuits, while powerful, are limited in their expressivity; the ability to verify circuits that deviate even slightly from strict stabilizer formalism is crucial for real-world implementation and optimisation. The previous limitation of tracking quantum states only up to a global phase introduced uncertainty in the verification process, potentially masking errors in circuit compilation or hardware execution. This new approach removes that am
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quantum-computingWellcome Leap Q4Bio Finalists Present Quantum Approaches to Biomedical Challenges
Insider Brief Wellcome Leap’s Quantum for Bio (Q4Bio) program concluded its final in-person milestone, with six finalist teams presenting hybrid quantum-classical approaches to biomedical problems. Delegates from leading quantum organizations and Nobel laureate John Martinis reviewed results across drug discovery and oncology biomarker identification. Winners will be announced in April 2026, with up to $7M in challenge prizes for experimental results on real quantum hardware. Wellcome Leap’s Quantum for Bio (Q4Bio) program, a $40M research initiative with up to $10M in challenge prizes, has reached its final in-person milestone. This week, the six finalist teams gathered in Marina del Rey to present their findings to a select group of invited delegates drawn from the highest ranks of the global quantum computing field. The Q4Bio program was launched to answer a deceptively simple question: can today’s quantum computers, noisy and limited as they are, do something genuinely useful for human health? After 30 months and three phases of rigorous evaluation, the teams are presenting their answers. Delegates invited to review the results include Ryan Babbush of Google Quantum AI, Gopal Karemore of IBM Research, Nathan Baker of Microsoft Quantum, Evgeny Epifanovsky of IonQ, Harry Buhrman and Christopher Langer of Quantinuum, Sam Pallister of PsiQuantum, and Alan Ho of QoLab. John Martinis, the 2025 Nobel Laureate in Physics, will join as a featured guest. “When we started the program, people didn’t know about any use cases where quantum can definitely impact biology,” said Shihan Sajeed, Q4Bio Program Director at Wellcome Leap. “We now know the fields where quantum can matter.” The six finalist teams have each developed hybrid quantum-classical approaches, combining quantum processors with classical high-performance computing to tackle biomedical problems ranging from drug discovery to oncology biomarker identification. The gathering in Marina del Rey is not a prize ceremo
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quantum-computingImplementing non-Abelian Hatano-Nelson model in electric circuits
--> Quantum Physics arXiv:2603.24642 (quant-ph) [Submitted on 25 Mar 2026] Title:Implementing non-Abelian Hatano-Nelson model in electric circuits Authors:Xiangru Chen, Jien Wu, Xingyu Chen, Zhenhang Pu, Yejian Hu, Jiuyang Lu, Manzhu Ke, Weiyin Deng, Zhengyou Liu View a PDF of the paper titled Implementing non-Abelian Hatano-Nelson model in electric circuits, by Xiangru Chen and 8 other authors View PDF Abstract:Non-Hermitian systems generally host complex spectra that bring unique spectral topologies, leading to the spectral braiding and non-Hermitian skin effect. The experimental exploration of non-Hermitian physics is mainly concentrated in artificial systems due to the flexibility in the introduction of the non-Hermiticity, but to date has focused only on the systems without gauge fields or with Abelian gauge fields. Here, we propose a non-Abelian Hatano-Nelson model with a nonreciprocal U(2) gauge field. The gauge field induces two non-Hermitian phenomena: the first is the Hopf-link-shaped complex energy braiding, and the second is the bipolar skin effect arising under the non-Abelian condition. The non-Abelian Hatano-Nelson model is implemented in electric circuits, and the Hopf-link-shaped admittance spectra and bipolar skin admittance modes are observed. Our work enriches the experimental non-Hermitian physics, and provides an approach to designing multifunctional non-Hermitian devices. Comments: Subjects: Quantum Physics (quant-ph); Mesoscale and Nanoscale Physics (cond-mat.mes-hall) Cite as: arXiv:2603.24642 [quant-ph] (or arXiv:2603.24642v1 [quant-ph] for this version) https://doi.org/10.48550/arXiv.2603.24642 Focus to learn more arXiv-issued DOI via DataCite Related DOI: https://doi.org/10.1103/48wx-5gmj Focus to learn more DOI(s) linking to related resources Submission history From: Yejian Hu [view email] [v1] Wed, 25 Mar 2026 12:39:03 UTC (10,888 KB) Full-text links: Access Paper: View a PDF of the paper titled Implementing non-Abelian Ha
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quantum-computingNeural Networks Simplify Quantum Error Correction, Reducing Decoding Complexity
A new decoding method for topological quantum error correction codes, specifically the toric code, offers more efficient hardware implementation. Luca Menti and Francisco Lázaro, at the Institute of Communications and Navigation German Aerospace Centre (DLR), have developed a neural belief-matching decoder streamlined by a convolutional architecture. This architecture enables the model to generalise from smaller code sizes to much larger, more complex instances without sacrificing accuracy. The method reduces the substantial training costs typically associated with neural network approaches and addresses a key challenge in realising practical quantum computers: correcting errors that inevitably arise during computation. It provides a strong and flexible set of tools, moving away from current techniques that combine belief-propagation with complex matching algorithms, which demand significant computational resources. Neural networks drastically accelerate decoding of topological quantum codes A substantial leap in efficiency for quantum error correction has been achieved, reducing the number of times the minimum-weight perfect matching (MWPM) decoder is called by up to four orders of magnitude. Previously, performing this important decoding step required immense computational power. Severely limiting the scalability of quantum systems was a major obstacle. This breakthrough now allows for practical implementation on larger, more complex codes, as a neural belief-matching decoder replaces standard belief-propagation with a neural network, streamlining the process and enabling weight sharing across the code’s structure. Quantum error correction (QEC) is paramount for building fault-tolerant quantum computers, as qubits are inherently susceptible to noise and decoherence. These errors, if left unchecked, rapidly corrupt quantum computations. Topological codes, such as the toric code, are particularly promising due to their inherent resilience to local errors and their p
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quantum-computingQuantum simulation of lattice gauge theories coupled to fermionic matter via anyonic regularization
--> Quantum Physics arXiv:2603.15820 (quant-ph) [Submitted on 16 Mar 2026] Title:Quantum simulation of lattice gauge theories coupled to fermionic matter via anyonic regularization Authors:Mason L. Rhodes, Shivesh Pathak, Riley W. Chien View a PDF of the paper titled Quantum simulation of lattice gauge theories coupled to fermionic matter via anyonic regularization, by Mason L. Rhodes and 2 other authors View PDF HTML (experimental) Abstract:The optimal regularization of infinite-dimensional degrees of freedom is a central open problem in the tractable simulation of lattice gauge theories on quantum computers. Here, we consider regularizing the gauge field by replacing the gauge group $G$ with a braided fusion category whose objects correspond to Wilson lines of the associated Chern-Simons theory $G_k$, with the level $k$ serving as the regularization parameter. We demonstrate how to couple these regularized $U(1)$ and $SU(2)$ gauge groups to fermionic matter using the framework of fusion surface models, which treats matter and gauge field excitations as interacting anyons. We then address the simulation of the Hamiltonians we construct on fault-tolerant quantum computers, providing explicit quantum circuit constructions for implementing the primitive gates in this model, namely, the $F$ and $R$ symbols of the $U(1)_k$ and $SU(2)_k$ anyon theories, which may be of independent interest. Subjects: Quantum Physics (quant-ph); Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics - Lattice (hep-lat) Cite as: arXiv:2603.15820 [quant-ph] (or arXiv:2603.15820v1 [quant-ph] for this version) https://doi.org/10.48550/arXiv.2603.15820 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Submission history From: Mason Rhodes [view email] [v1] Mon, 16 Mar 2026 18:51:41 UTC (502 KB) Full-text links: Access Paper: View a PDF of the paper titled Quantum simulation of lattice gauge theories coupled to fermionic matter via anyonic regu
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quantum-computingStandard Qubit Error Correction is Hitting a Wall. I Propose 'Topological Qubit Surgery' (The $di$ Architecture) – A Biologically-Inspired Framework.
Hey r/QuantumComputing and r/HypotheticalPhysics, We all know the current bottleneck in scaling quantum computers: environmental noise and the immense overhead of standard error correction codes. But what if we are approaching the problem from the wrong angle? What if we look at how biological systems (like codon repair mechanisms) handle microscopic errors and translate that into quantum topology? I’ve been working on a new theoretical framework I call the $di$ Architecture, and I just published the preprint. Here is the core of the dfi theory: The Problem: Classical spatial noise destroys coherence. The Mechanism: Instead of just adding more physical qubits for redundancy, this framework introduces Topological Qubit Surgery. It utilizes macroscopic topological defects ($d$) paired with an imaginary time wave engine ($i$). The Math: By mapping a 64-state tensor network and applying concepts like Hironaka's resolution of singularities and Perelman's Ricci flow, the architecture mathematically "excises" geometric errors before they cascade. It’s essentially a self-healing, fault-tolerant topological network. I know this sounds like a massive paradigm shift—bridging biological self-healing inspiration with pure topological quantum mechanics. That’s exactly why I want this community to tear it apart, critique it, and discuss the mathematical soundness of the $di$ state. I have permanently archived the full theory, mathematical proofs, and data on Zenodo to ensure it remains open and uncensored. 🔗 Read the full paper here (DOI):https://zenodo.org/records/19078543 I’ll be in the comments to defend the math and answer any questions. Let’s get into it. TL;DR: Introducing the "dfi theory"—a mathematically backed, biologically-inspired approach to quantum error correction using Topological Qubit Surgery. Full preprint linked above. submitted by /u/Glum_Journalist_4897 [link] [comments]
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quantum-computingTheory of the Matchgate Commutant
--> Quantum Physics arXiv:2603.12392 (quant-ph) [Submitted on 12 Mar 2026] Title:Theory of the Matchgate Commutant Authors:Piotr Sierant, Xhek Turkeshi, Poetri Sonya Tarabunga View a PDF of the paper titled Theory of the Matchgate Commutant, by Piotr Sierant and 2 other authors View PDF Abstract:In quantum information theory and statistical physics, symmetries of multiple copies, or replicas, of a system play a pivotal role. For unitary ensembles, these symmetries are encoded in the replicated commutant: the algebra of operators commuting with the ensemble across $k$ replicas. Determining the commutant is straightforward for the full unitary group, but remains a major obstacle for structured, computationally relevant circuit families. We solve this problem for matchgate circuits, which prepare fermionic Gaussian states on $n$ qubits. Using a Majorana fermion representation, we show that operators coupling different system copies generate the orthogonal Lie algebra $\mathfrak{so}(k)$, endowing the space of invariants with rich and tractable structure. This underlying symmetry decomposes the matchgate commutant into irreducible sectors, which we completely resolve via a Gelfand--Tsetlin construction. We provide an explicit orthonormal basis of the matchgate commutant for all $k$ and $n$, together with a formula for its dimension that grows polynomially in $n$. Furthermore, we characterize the commutant of the Clifford--matchgate subgroup, showing that restricting to signed permutations of Majorana modes yields a commutant that qualitatively diverges from the matchgate case for $k \geq 4$ replicas. Ultimately, our orthonormal basis turns algebraic classification into a working toolbox. Using it, we derive closed-form expressions for matchgate twirling channels and a fermionic analogue of Weingarten calculus, the projector encoding all moments of the Gaussian state orbit, state and unitary frame potentials, the average nonstabilizerness of fermionic Gaussian states, a s
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quantum-computingQuantum Computers Move Closer with New Universal Code Design
A pathway towards universal quantum computation utilising group surface codes expands upon existing quantum error correction techniques. Naren Manjunath from the Perimeter Institute for Theoretical Physics, Vieri Mattei from Purdue University, Apoorv Tiwari from the Centre for Quantum Mathematics & Danish Institute for Advanced Study (Danish IAS) and Southern Denmark University, and Tyler D. Ellison from the Perimeter Institute for Theoretical Physics, Purdue University, and Purdue Quantum Science and Engineering Institute, detail how these codes – equivalent to quantum double models of finite groups – enable non-Clifford gates within established 2 surface codes. This work offers a means of achieving universal quantum computation without relying on the braiding of anyons. Importantly, it circumvents limitations imposed by the Bravyi-König theorem on topological Pauli stabilizer models. The codes represent a key development as they provide a flexible set of tools for quantum computation and represent a strong alternative to existing methods. This collaborative work, conducted across the Perimeter Institute for Theoretical Physics, Purdue University, Centre for Quantum Mathematics & Danish Institute for Advanced Study (Danish IAS), Southern Denmark University, and Purdue Quantum Science and Engineering Institute, offers a means of achieving universal quantum computation without relying on the braiding of anyons. It also circumvents limitations imposed by the Bravyi-König theorem on topological Pauli stabilizer models. The codes represent a key development as they provide a flexible set of tools for quantum computation and represent a strong alternative to existing methods. Transversal implementation of classical gates unlocks low-overhead quantum error correction Error rates dropped to 0.6% when implementing arbitrary reversible classical gates transversally—a strong improvement over previous methods requiring rates above 10%. This breakthrough, utilising grou
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quantum-computingUtility-Scale Quantum State Preparation: Classical Training using Pauli Path Simulation
AbstractWe use Pauli Path simulation to variationally obtain parametrized circuits for preparing ground states of various quantum many-body Hamiltonians. These include the quantum Ising model in one dimension, in two dimensions on square and heavy-hex lattices, and the Kitaev honeycomb model, all at system sizes of one hundred qubits or more – sizes at which generic quantum circuits are beyond the reach of exact state-vector simulation – thereby reaching utility scale. We benchmark the Pauli Path simulation results against exact ground-state energies when available, and against density-matrix renormalization group calculations otherwise, finding strong agreement. To further assess the quality of the variational states, we evaluate the magnetization in the x and z directions for the quantum Ising models and compute the topological entanglement entropy for the Kitaev honeycomb model. Finally, we prepare approximate ground states of the Kitaev honeycomb model with 48 qubits, in both the gapped and gapless regimes, on Quantinuum's System Model H2 quantum computer using parametrized circuits obtained from Pauli Path simulation. We achieve a relative energy error of approximately $5\%$ without error mitigation and demonstrate the braiding of Abelian anyons on the quantum device beyond fixed-point models.Featured image: A modified framework for variational quantum algorithms in which the quantum circuit calculations are performed via classical simulation.Popular summaryOne of the most promising applications of quantum computers is quantum simulation, where preparing the lowest-energy, or ground-state, quantum wavefunctions on quantum hardware is a key task. A common approach is to design a parameterized circuit to prepare such a ground state, with the parameters optimized by minimizing the energy within a variational framework. Typically, the energy and its gradient are evaluated using quantum hardware. However, limited access to quantum devices makes this procedure very c
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quantum-computingEmergence of Coherence in Nonequilibrium and Structured Environments
Emergence of Coherence in Nonequilibrium and Structured Environments Acronym: eco-noise2026Dates: Thursday, July 23, 2026 to Tuesday, July 28, 2026Web page: eco-noise2026Registration deadline: Friday, May 15, 2026Submission deadline: Friday, May 15, 2026Tags: nonequilibrium quantum many-body physics; driven quantum materials; cavity physics; ultrafast phenomena; superconductors; ultracold atoms; quantum simulationThe eco-noise2026 workshop, “Emergence of Coherence in Nonequilibrium and Structured Environments,” will take place at the Ettore Majorana Foundation and Centre for Scientific Culture in Erice, Italy, from 23 to 28 July 2026. For the abstract and the list of invited speakers, please check out the details below and our website. Applications are now open for contributed talks, posters, and participants. Please check out our website for registration and submission information. Registration deadline: 15 May 2026 For further questions regarding the workshop, please contact the organisers at eco.noise2026@gmail.com. Organizers Eugene Demler (ETH), Andrea Cavalleri (MPSD), Angel Rubio (MPSD), Marios Michael (MPI-PKS), Duilio De Santis (ETH), Hope Bretscher (MPSD) Abstract Driving quantum many-body systems with an external source has been explored as a route to control the collective properties of quantum matter. Recently, studies of cavity–matter hybrids have suggested that dynamical control need not be coherent: quantum or thermal noise from light inside an optical cavity can be used to passively control phases of matter. In this workshop, we aim to merge these two communities that sit at different limits along the spectrum of dynamical control. The central question we seek to address is: how can nonequilibrium and engineered environments, ranging from laser driving to cavity-mediated noise, be leveraged to enhance coherence in many-body quantum systems? In particular, we are interested in exploring the boundaries of how fragile but
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quantum-computingPhase-space complexity of discrete-variable quantum states and operations
--> Quantum Physics arXiv:2603.03431 (quant-ph) [Submitted on 3 Mar 2026] Title:Phase-space complexity of discrete-variable quantum states and operations Authors:Siting Tang, Shunlong Luo, Matteo G. A. Paris View a PDF of the paper titled Phase-space complexity of discrete-variable quantum states and operations, by Siting Tang and 2 other authors View PDF HTML (experimental) Abstract:We introduce a quantifier of phase-space complexity for discrete-variable (DV) quantum systems. Motivated by a recent framework developed for continuous-variable systems, we construct a complexity measure of quantum states based on the Husimi Q-function defined over spin coherent states. The quantifier combines into a single scalar quantity two complementary information-theoretic quantities, the Wehrl entropy, which captures phase-space spread, and the Fisher information, which captures localization. We derive fundamental properties of this measure, including its invariance under SU(2) displacements. The complexity is normalized such that coherent states have unit complexity, while the completely mixed state has zero complexity, a feature distinct from the continuous-variable case. We provide analytic expressions for several relevant families of states, including Gibbs and Dicke states, and perform a numerical analysis of spin-squeezed states, NOON states, and randomly generated states. Numerical results reveal a monotonic, but not deterministic, relationship between complexity and purity, leading us to conjecture that maximal complexity is attained by pure states, thereby connecting the problem to the optimization of Wehrl entropy via Majorana constellations. Finally, we extend the framework to quantum channels, defining measures for both the generation and breaking of complexity. We analyze the performance of common unitary gates and the amplitude damping channel, showing that while low-dimensional systems can achieve maximal complexity via spin squeezing or NOON states, this becomes
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quantum-computingResource-Efficient Emulation of Majorana Zero Mode Braiding on a Superconducting Trijunction
--> Quantum Physics arXiv:2603.03645 (quant-ph) [Submitted on 4 Mar 2026] Title:Resource-Efficient Emulation of Majorana Zero Mode Braiding on a Superconducting Trijunction Authors:Rahul Signh, Weixin Lu, Kaelyn J Ferris, Javad Shabani View a PDF of the paper titled Resource-Efficient Emulation of Majorana Zero Mode Braiding on a Superconducting Trijunction, by Rahul Signh and 3 other authors View PDF HTML (experimental) Abstract:Topological superconductivity could host quasiparticles that are key candidates for fault-tolerant quantum computation due to their immunity to noise as they obey non-Abelian exchange statistics. For example, in the case of Majorana Zero Modes (MZM), braiding enables two topologically protected quantum gates. While their direct manipulation in solid-state systems remains experimentally challenging, digital emulation of MZM behavior has provided insight as well as a deeper understanding of controlling these topological quantum systems. This emulation is typically accomplished by mapping the topological and trivial phases of a Majorana system to ferromagnetic and paramagnetic Hamiltonians of a spin-glass model. This approach usually relies on adiabatic evolution of superconducting Hamiltonians, which require circuits with very large depths. In this work, we present a resource-efficient method to emulate MZM braiding in a trijunction geometry using a quantum processor. We introduce direct braiding operators which simulate the evolution more efficiently, reducing the quantum gate overhead. We then further generalize this method to emulate braiding operations in extended trijunction architectures based on Kitaev chains. Comments: Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2603.03645 [quant-ph] (or arXiv:2603.03645v1 [quant-ph] for this version) https://doi.org/10.48550/arXiv.2603.03645 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Submission history From: Kaelyn Ferris [view email] [v1] Wed, 4 Ma
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quantum-computingPurdue Names Michael Manfra Chief Quantum Officer
Insider Brief Michael Manfra has been appointed chief quantum officer at Purdue University, effective January 1, 2026, while continuing as director of the Purdue Quantum Science and Engineering Institute. In the newly created role, Manfra will oversee Purdue’s quantum research portfolio, industry and government partnerships, and educational programs, and advise university leadership on integrating quantum efforts into the Purdue Computes initiative. Manfra is recognized for experimental work demonstrating evidence of anyons and previously served in leadership roles at Bell Laboratories and Microsoft Quantum. PRESS RELEASE — Purdue University announced Tuesday (March 3) that quantum computing expert Michael Manfra has been appointed chief quantum officer, effective Jan. 1, 2026. He is currently director of the Purdue Quantum Science and Engineering Institute (PQSEI). In this newly established joint role, Manfra — the Bill and Dee O’Brien Distinguished Professor of Physics and Astronomy, professor in the Elmore Family School of Electrical and Computer Engineering, and professor of materials engineering — will strategically guide Purdue’s quantum portfolio including its engagement with industry and government partners, educational activities, and serve as special advisor to university President Mung Chiang and Provost Patrick Wolfe to integrate quantum research into the broader Purdue Computes initiative. “Mike is the right person, and now is the right time, for this appointment, given the potential of quantum technologies to transform our future,” Wolfe said. “A team player for Purdue and someone whose research career has consistently generated important firsts, Mike’s strategic understanding of the broad and promising landscape in quantum science and engineering will position us well to advance and integrate our growing quantum research portfolio.” The need for highly skilled talent in quantum science and technology is expected to grow dramatically in the n
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quantum-computingNQCC SparQ Access Programme Supports Academic Research with Quantum Resources
The National Quantum Computing Centre is now accepting applications for its SparQ Access programme, offering the UK academic community access to a diverse array of quantum computing platforms. This initiative, part of the broader ‘SparQ’ effort to bolster quantum readiness within the nation, aims to accelerate scientific research and innovation by removing barriers to utilizing advanced quantum resources. Researchers at UK universities can request access to systems including Azure Quantum, Rigetti Ankaa-2, and IBM Quantum’s suite of processors, with awards granted on a rolling three-month basis; applications for the period of 1st May, 31st July 2026 are now open, and the deadline to submit is 4pm on 27th March 2026. The programme also supports collaborative Proof of Concepts projects, integrating quantum computing resources directly into awarded funding packages. NQCC SparQ Access Programme Supports UK Quantum Readiness Over 20 distinct quantum computing platforms are now accessible to researchers and innovators across the United Kingdom through the National Quantum Computing Centre’s SparQ Access programme, a key component of the broader SparQ initiative designed to bolster national quantum readiness. Currently, the NQCC offers access to a diverse range of hardware, encompassing both superconducting and trapped ion technologies, as well as a suite of simulators like the H1-1 Emulator and IBM’s offerings, including the IBM Torino and IBM Marrakesh systems. Beyond direct access, the NQCC integrates quantum computing resources into awards from its funding calls, and is open to proposals for delivering programmes aligned with UK quantum readiness objectives from partner councils or institutions. Furthermore, collaborative Proof of Concepts projects are now being offered as part of the award package, providing additional support for use-case discovery, according to the NQCC; interested parties are encouraged to monitor Funding opportunities, NQCC for the latest calls. A
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