IF 6.4 2区物理与天体物理

Quantum Pub Date : 2026-10-08 DOI: 10.22331/q-2026-10-08-2231

Lucas Tendick, Costantino Budroni, Marco Túlio Quintino

{"title":"Strict hierarchy between $n$-wise measurement simulability, compatibility structures, and multi-copy compatibility","authors":"Lucas Tendick, Costantino Budroni, Marco Túlio Quintino","doi":"10.22331/q-2026-10-08-2231","DOIUrl":"https://doi.org/10.22331/q-2026-10-08-2231","url":null,"abstract":"The incompatibility of quantum measurements, i.e. the fact that certain observable quantities cannot be measured jointly is widely regarded as a distinctive quantum feature with important implications for the foundations and the applications of quantum information theory. While the standard incompatibility of multiple measurements has been the focus of attention since the inception of quantum theory, its generalizations, such as measurement simulability, $n$-wise incompatibility, and mulit-copy incompatibility have only been proposed recently. Here, we point out that all these generalizations are differing notions of the question of how many measurements are genuinely contained in a measurement device. We then show, that all notions do differ not only in their operational meaning but also mathematically in the set of measurement assemblages they describe. We then fully resolve the relations between these different generalizations, by showing a strict hierarchy between these notions. Hence, we provide a general framework for generalized measurement incompatibility. Finally, we consider the implications our results have for recent works using these different notions.","PeriodicalId":20807,"journal":{"name":"Quantum","volume":"91 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149123734","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Enhanced measurements on quantum computers via the simultaneous probing of non-commuting Pauli operators 通过同时探测非交换泡利算子增强量子计算机上的测量

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2026-10-07 DOI: 10.22331/q-2026-10-07-2229

Rick P. A. Simon,Zheng Shi,Charlie Nation,Andrew Jena,Luca Dellantonio

引用次数: 0

Quantum Graph Theory by Example 量子图论举例

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2026-10-06 DOI: 10.22331/q-2026-10-06-2228

Gian Luca Spitzer, Ion Nechita

{"title":"Quantum Graph Theory by Example","authors":"Gian Luca Spitzer, Ion Nechita","doi":"10.22331/q-2026-10-06-2228","DOIUrl":"https://doi.org/10.22331/q-2026-10-06-2228","url":null,"abstract":"Quantum graphs have been introduced by Duan, Severini, and Winter to describe the zero-error behaviour of quantum channels. Since then, quantum graph theory has become a field of study in its own right. A substantial source of difficulty in working with quantum graphs compared to classical graphs stems from the fact that they are no longer discrete objects. This makes it generally difficult to construct insightful, non-trivial examples. We present a collection of non-trivial quantum graphs that can be thought of in discrete terms, and that can be expressed in the diagrammatic formalism introduced by Musto, Reutter, and Verdon. The examples arise as the quantum graphs acted on by increasingly smaller classical matrix groups, and are parametrised by triples of matrices $(A, B, C)$. The parametrisation reveals a clean decomposition of quantum graph structure into classical and genuinely quantum components: $A$ and $C$ are described by a classical weighted graph called the strange graph, while $B$ provides a purely quantum contribution with no classical analogue. Based on this model, we give exact formulas or establish bounds for quantum graph parameters, such as the number of connected components, the chromatic number, the independence number, and the clique number. Our results provide the first large, parametric families of quantum graphs for which standard graph parameters can be computed analytically.","PeriodicalId":20807,"journal":{"name":"Quantum","volume":"1 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149087156","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Limits to black-box amplification in QMA QMA中黑盒放大的限制

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2026-10-06 DOI: 10.22331/q-2026-10-06-2227

Scott Aaronson, Phillip Harris, Freek Witteveen

引用次数: 0

Fast Bosonic Control via Multiphoton Qubit-Oscillator Interactions 基于多光子量子-振荡器相互作用的快速玻色子控制

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2026-10-01 DOI: 10.22331/q-2026-10-01-2224

Noah Gorgichuk, Mohammad Ayyash, Matteo Mariantoni, Sahel Ashhab

{"title":"Fast Bosonic Control via Multiphoton Qubit-Oscillator Interactions","authors":"Noah Gorgichuk, Mohammad Ayyash, Matteo Mariantoni, Sahel Ashhab","doi":"10.22331/q-2026-10-01-2224","DOIUrl":"https://doi.org/10.22331/q-2026-10-01-2224","url":null,"abstract":"We study the problem of $n$-fold rotationally symmetric bosonic state preparation, which is of great importance to bosonic quantum error correction, using a multiphoton interaction between an oscillator and an auxiliary qubit. We present an $n$-photon Law-Eberly ($n$LE) protocol that serves as an analytic baseline, alongside numerical optimal control calculations that further reduce state preparation time. We find that multiphoton control protocols substantially reduce preparation times for binomial, cat, and Gottesman-Kitaev-Preskill codewords compared to schemes relying on standard linear interactions. Further, we achieve arbitrary control over the oscillator's Hilbert space by combining different multiphoton interaction orders. We also extend these control improvements to the preparation of rotationally symmetric multi-oscillator states. Lastly, numerical simulations using realistic planar superconducting circuit parameters validate the robustness of our scheme against qubit and oscillator decoherence. Our findings can significantly enhance the performance of bosonic codes on planar superconducting hardware, an important ingredient for scalable fault-tolerant quantum computers.","PeriodicalId":20807,"journal":{"name":"Quantum","volume":"55 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149083826","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Spinor Bose-Einstein condensate as an analog simulator of molecular bending vibrations 旋量玻色-爱因斯坦凝聚作为分子弯曲振动的模拟模拟器

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2026-10-01 DOI: 10.22331/q-2026-10-01-2226

Ayaka Usui, Artur Niezgoda, Manuel Gessner

{"title":"Spinor Bose-Einstein condensate as an analog simulator of molecular bending vibrations","authors":"Ayaka Usui, Artur Niezgoda, Manuel Gessner","doi":"10.22331/q-2026-10-01-2226","DOIUrl":"https://doi.org/10.22331/q-2026-10-01-2226","url":null,"abstract":"We demonstrate that spinor Bose-Einstein condensates (BECs) can be operated as an analog simulator of the two-dimensional vibron model. This algebraic model describes bending vibrations of molecules and, in the case of triatomic molecules, exhibits two phases where linear and bent configurations are stabilised. Spinor BECs can be engineered to simulate states that correspond to linear or bent triatomic molecules, with the Wigner function of the BEC encoding information about the molecular configuration. We show how quantum simulations of the bending dynamics of linear molecules can be realised, and how preparing a linear configuration in the bent phase leads to a dynamical instability. In the dynamics triggered by the corresponding instability, a significant amount of entanglement is generated, and we characterise the dynamics with the squeezing parameter and the quantum Fisher information (QFI). The scaling of the non-Gaussian sensitivity, described by the difference between squeezing and QFI, grows with the system size once the spinor system crosses from the linear to the bent phase, thus serving as a dynamical witness for the quantum phase transition.","PeriodicalId":20807,"journal":{"name":"Quantum","volume":"196 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149083830","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

GPU-Accelerated Quantum Simulation of Stabilizer Circuits 稳定电路的gpu加速量子模拟

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2026-10-01 DOI: 10.22331/q-2026-10-01-2225

Muhammad Osama, Dimitrios Thanos, Alfons Laarman

{"title":"GPU-Accelerated Quantum Simulation of Stabilizer Circuits","authors":"Muhammad Osama, Dimitrios Thanos, Alfons Laarman","doi":"10.22331/q-2026-10-01-2225","DOIUrl":"https://doi.org/10.22331/q-2026-10-01-2225","url":null,"abstract":"We introduce new parallel algorithms for efficiently simulating stabilizer (Clifford) circuits on GPUs, with a focus on data-parallel tableau evolution and scalable handling of projective measurements. Our approach reformulates key bottlenecks in stabilizer simulation – such as Gaussian elimination and measurement updates – into GPU-tailored primitives that eliminate sequential dependencies and maximize memory coalescing. We implement these techniques in QuaSARQ, a GPU-accelerated stabilizer simulator designed for large qubit counts and many-shot sampling. Across a broad benchmark suite reaching 180,000 qubits and depth 1,000 (roughly 130M gates), QuaSARQ shows substantial runtime improvements, with up to 105$times$ speedup, and over 80% energy reduction on demanding instances. Moreover, QuaSARQ consistently outperforms Stim, a state-of-the-art CPU-optimized stabilizer simulator, as well as Qiskit-Aer (CPU/GPU), Qibo, Cirq, and PennyLane. Finally, QuaSARQ exhibits a significant advantage in many-shot sampling on large workloads. These results demonstrate that our parallel algorithms can significantly advance the scalability of stabilizer-circuit simulation, particularly for workloads involving extensive measurements and sampling.","PeriodicalId":20807,"journal":{"name":"Quantum","volume":"481 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149083828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Lifting the maximally-entangledness assumption in robust self-testing for synchronous games 提升同步游戏鲁棒自测中的最大纠缠度假设

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2026-10-01 DOI: 10.22331/q-2026-10-01-2222

Matthijs Vernooij, Yuming Zhao

引用次数: 0

Universal Dilation of Linear Itô SDEs: Quantum Trajectories and Lindblad Simulation of Second Moments 线性SDEs的普遍膨胀Itô：量子轨迹和秒矩的Lindblad模拟

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2026-10-01 DOI: 10.22331/q-2026-10-01-2223

Hsuan-Cheng Wu, Xiantao Li

{"title":"Universal Dilation of Linear Itô SDEs: Quantum Trajectories and Lindblad Simulation of Second Moments","authors":"Hsuan-Cheng Wu, Xiantao Li","doi":"10.22331/q-2026-10-01-2223","DOIUrl":"https://doi.org/10.22331/q-2026-10-01-2223","url":null,"abstract":"We present a universal framework for simulating $N$-dimensional linear Itô stochastic differential equations (SDEs) on quantum computers with additive or multiplicative noises. Building on a unitary dilation technique, we establish a rigorous mapping from the general linear SDEs $ dX_t = A(t) X_t dt + sum_{j=1}^J B_j(t)X_t dW_t^j $ to stochastic Schrödinger equations (SSE) on a dilated Hilbert space. Crucially, this embedding is pathwise exact in that the classical solution is recovered as a projection of the dilated quantum state for each fixed noise realization. We demonstrate that the resulting SSEs are naturally implementable on digital quantum processors, where the stochastic Wiener increments are encoded directly by preparing the ancillary qubits. Exploiting this physical mapping, we develop two algorithmic strategies: (1) a trajectory-based approach that uses sequential weak measurements to realize efficient stochastic integrators, including a second-order scheme, and (2) an ensemble-based approach that maps moment evolution to a deterministic Lindblad quantum master equation, enabling simulation without Monte Carlo sampling. We provide error bounds based on a stochastic light-cone analysis and validate the framework with numerical experiments.","PeriodicalId":20807,"journal":{"name":"Quantum","volume":"167 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149083827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Performance of the spin qubit shuttling architecture for a surface code implementation 自旋量子比特穿梭结构的表面代码实现性能

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2026-09-30 DOI: 10.22331/q-2026-09-30-2219

Berat Yenilen, Arnau Sala, Hendrik Bluhm, Markus Müller, Manuel Rispler

{"title":"Performance of the spin qubit shuttling architecture for a surface code implementation","authors":"Berat Yenilen, Arnau Sala, Hendrik Bluhm, Markus Müller, Manuel Rispler","doi":"10.22331/q-2026-09-30-2219","DOIUrl":"https://doi.org/10.22331/q-2026-09-30-2219","url":null,"abstract":"Qubit shuttling promises to advance some quantum computing platforms to the qubit register sizes needed for effective quantum error correction (QEC), but also introduces additional errors whose impact must be evaluated. The established method to investigate the performance of QEC codes in a realistic scenario is to employ a standard noise model known as circuit-level noise, where all quantum operations are modeled as noisy. In the present work, we take this noise model and single out the effect of shuttling errors by introducing them as an additional so-called error location. This hardware abstraction is motivated by the SpinBus architecture and allows a systematic numerical investigation to map out the resulting two-dimensional parameter space. To this end, we take the Surface code and perform large scale simulations, most notably extracting the threshold across said two-dimensional parameter space. We study two scenarios for shuttling errors, depolarization on the one hand and dephasing on the other hand. For a purely dephasing shuttling error, we find a threshold of several percent, provided that all other operations have a high fidelity. The qubit overhead needed to reach a logical error rate of $10^{-12}$ (known as the \"teraquop\" regime [23] increases only moderately for shuttling error rates up to about 1 % per shuttling operation. The error rates at which practically useful, i.e. well below threshold error correction is predicted to be possible are comfortably higher than what is expected to be achievable for spin qubits. Our results thus show that it is reasonable to expect shuttling operations to fall below threshold already at surprisingly large error rates. With realistic efforts in the near term, this offers positive prospects for spin qubit based quantum processors as a viable avenue for scalable fault-tolerant error-corrected quantum computing.","PeriodicalId":20807,"journal":{"name":"Quantum","volume":"66 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149078083","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

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