Quantum最新文献 - Book学术

Low variance estimations of many observables with tensor networks and informationally-complete measurements 用张量网络和信息完备的测量对许多可观测值进行低方差估计

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-07-23 DOI: 10.22331/q-2025-07-23-1812

Stefano Mangini, Daniel Cavalcanti

引用次数: 0

Experiments with Schrödinger Cellular Automata Schrödinger细胞自动机实验

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-07-23 DOI: 10.22331/q-2025-07-23-1811

Kees van Berkel, Jan de Graaf, Kees van Hee

引用次数: 0

Graphical Framework for Non-Gaussian Quantum States 非高斯量子态的图形框架

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-07-23 DOI: 10.22331/q-2025-07-23-1809

Lina Vandré, Boxuan Jing, Yu Xiang, Otfried Gühne, Qiongyi He

引用次数: 0

Circuit-level fault tolerance of cat codes cat码的电路级容错

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-07-23 DOI: 10.22331/q-2025-07-23-1810

Long D. H. My, Shushen Qin, Hui Khoon Ng

{"title":"Circuit-level fault tolerance of cat codes","authors":"Long D. H. My, Shushen Qin, Hui Khoon Ng","doi":"10.22331/q-2025-07-23-1810","DOIUrl":"https://doi.org/10.22331/q-2025-07-23-1810","url":null,"abstract":"Bosonic codes encode quantum information into a single infinite-dimensional physical system endowed with error correction capabilities. This reduces the need for complex management of many physical constituents compared with standard approaches employing multiple physical qubits. Recent discussions of bosonic codes centre around correcting only boson-loss errors, with phase errors either actively suppressed or deferred to subsequent layers of encoding with standard qubit codes. Rotationally symmetric bosonic (RSB) codes, which include the well-known cat and binomial codes, are capable of simultaneous correction of loss and phase errors, offering an alternate route that deals with arbitrary errors already at the base layer. Here, we investigate the robustness of such codes, moving away from the more idealistic past studies towards a circuit-level noise analysis closer to the practical situation where every physical component in the device is potentially faulty. We extend the concept of fault tolerance to the case of RSB codes, and then examine the performance of two known error correction circuits under circuit-level noise. Our analysis reveals a significantly more stringent noise threshold for fault-tolerant operation than found in past works; nevertheless, we show how, through waiting-time optimization and the use of squeezing, we can restore the noise requirements to a regime achievable with near-term quantum hardware. While our focus here is on cat codes for concreteness, a similar analysis applies for general RSB codes.","PeriodicalId":20807,"journal":{"name":"Quantum","volume":"10 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144685145","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

Neural Projected Quantum Dynamics: a systematic study 神经投射量子动力学：一个系统的研究

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-07-22 DOI: 10.22331/q-2025-07-22-1803

Luca Gravina, Vincenzo Savona, Filippo Vicentini

引用次数: 0

Bounds on Autonomous Quantum Error Correction 自主量子纠错的边界

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-07-22 DOI: 10.22331/q-2025-07-22-1804

Oles Shtanko, Yu-Jie Liu, Simon Lieu, Alexey V. Gorshkov, Victor V. Albert

{"title":"Bounds on Autonomous Quantum Error Correction","authors":"Oles Shtanko, Yu-Jie Liu, Simon Lieu, Alexey V. Gorshkov, Victor V. Albert","doi":"10.22331/q-2025-07-22-1804","DOIUrl":"https://doi.org/10.22331/q-2025-07-22-1804","url":null,"abstract":"Autonomous quantum memories are a way to passively protect quantum information using engineered dissipation that creates an “always-on'' decoder. We analyze Markovian autonomous decoders that can be implemented with a wide range of qubit and bosonic error-correcting codes, and derive several upper bounds and a lower bound on the logical error rate in terms of correction and noise rates. These bounds suggest that, in general, there is always a correction rate, possibly size-dependent, above which autonomous memories exhibit arbitrarily long coherence times. For any given autonomous memory, size dependence of this correction rate is difficult to rule out: we point to common scenarios where autonomous decoders that stochastically implement active error correction must operate at rates that grow with code size. For codes with a threshold, we show that it is possible to achieve faster-than-polynomial decay of the logical error rate with code size by using superlogarithmic scaling of the correction rate. We illustrate our results with several examples. One example is an exactly solvable global dissipative toric code model that can achieve an effective logical error rate that decreases exponentially with the linear lattice size, provided that the recovery rate grows proportionally with the linear lattice size.","PeriodicalId":20807,"journal":{"name":"Quantum","volume":"113 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144677381","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

Certifying nonlocal properties of noisy quantum operations 证明有噪声量子运算的非局域性质

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-07-22 DOI: 10.22331/q-2025-07-22-1807

Albert Rico, Moisés Bermejo Morán, Fereshte Shahbeigi, Karol Życzkowski

{"title":"Certifying nonlocal properties of noisy quantum operations","authors":"Albert Rico, Moisés Bermejo Morán, Fereshte Shahbeigi, Karol Życzkowski","doi":"10.22331/q-2025-07-22-1807","DOIUrl":"https://doi.org/10.22331/q-2025-07-22-1807","url":null,"abstract":"Certifying quantum properties from the probability distributions they induce is an important task for several purposes. While this framework has been largely explored and used for quantum states, its extrapolation to the level of channels started recently in a variety of approaches. In particular, little is known about to what extent noise can spoil certification methods for channels. In this work we provide a unified methodology to certify nonlocal properties of quantum channels from the correlations obtained in prepare-and-measurement protocols: our approach gathers fully and semi-device-independent existing methods for this purpose, and extends them to new certification criteria. In addition, the effect of different models of dephasing noise is analysed. Some noise models are shown to generate nonlocality and entanglement in special cases. In the extreme case of complete dephasing, the measurement protocols discussed yield particularly simple tests to certify nonlocality, which can be obtained from known criteria by fixing the dephasing basis. These are based on the relations between bipartite quantum channels and their classical analogues: bipartite stochastic matrices defining conditional distributions.","PeriodicalId":20807,"journal":{"name":"Quantum","volume":"99 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144677695","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

Symmetry verification for noisy quantum simulations of non-Abelian lattice gauge theories 非阿贝尔晶格规范理论的噪声量子模拟对称性验证

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-07-22 DOI: 10.22331/q-2025-07-22-1802

Edoardo Ballini, Julius Mildenberger, Matteo M. Wauters, Philipp Hauke

{"title":"Symmetry verification for noisy quantum simulations of non-Abelian lattice gauge theories","authors":"Edoardo Ballini, Julius Mildenberger, Matteo M. Wauters, Philipp Hauke","doi":"10.22331/q-2025-07-22-1802","DOIUrl":"https://doi.org/10.22331/q-2025-07-22-1802","url":null,"abstract":"Non-Abelian gauge theories underlie our understanding of fundamental forces of modern physics. Simulating them on quantum hardware is an outstanding challenge in the rapidly evolving field of quantum simulation. A key prerequisite is the protection of local gauge symmetries against errors that, if unchecked, would lead to unphysical results. While an extensive toolkit devoted to identifying, mitigating, and ultimately correcting such errors has been developed for Abelian groups, non-commuting symmetry operators complicate the implementation of similar schemes in non-Abelian theories. Here, we discuss two techniques for error mitigation through symmetry verification, tailored for non-Abelian lattice gauge theories implemented in noisy qudit hardware: dynamical post-selection (DPS), based on mid-circuit measurements without active feedback, and post-processed symmetry verification (PSV), which combines measurements of correlations between target observables and gauge transformations. We illustrate both approaches for the discrete non-Abelian group $D_3$ in 2+1 dimensions, explaining their usefulness for current NISQ devices even in the presence of fast fluctuating noise. Our results open new avenues for robust quantum simulation of non-Abelian gauge theories, for further development of error-mitigation techniques, and for measurement-based control methods in qudit platforms.","PeriodicalId":20807,"journal":{"name":"Quantum","volume":"115 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144677379","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

Critical spin models from holographic disorder 来自全息无序的临界自旋模型

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-07-22 DOI: 10.22331/q-2025-07-22-1808

Dimitris Saraidaris, Alexander Jahn

引用次数: 0

Dictionary-based Block Encoding of Sparse Matrices with Low Subnormalization and Circuit Depth 基于字典的低次归一化和电路深度稀疏矩阵分块编码

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-07-22 DOI: 10.22331/q-2025-07-22-1805

Chunlin Yang, Zexian Li, Hongmei Yao, Zhaobing Fan, Guofeng Zhang, Jianshe Liu

{"title":"Dictionary-based Block Encoding of Sparse Matrices with Low Subnormalization and Circuit Depth","authors":"Chunlin Yang, Zexian Li, Hongmei Yao, Zhaobing Fan, Guofeng Zhang, Jianshe Liu","doi":"10.22331/q-2025-07-22-1805","DOIUrl":"https://doi.org/10.22331/q-2025-07-22-1805","url":null,"abstract":"Block encoding severs as an important data input model in quantum algorithms, enabling quantum computers to simulate non-unitary operators effectively. In this paper, we propose an efficient block-encoding protocol for sparse matrices based on a novel data structure, called the dictionary data structure, which classifies all non-zero elements according to their values and indices. Non-zero elements with the same values, lacking common column and row indices, belong to the same classification in our block-encoding protocol's dictionary. When compiled into the $textit{{U(2), CNOT}}$ gate set, the protocol queries a $2^n times 2^n$ sparse matrix with $s$ non-zero elements at a circuit depth of $mathcal{O}(log(ns))$, utilizing $mathcal{O}(n^2s)$ ancillary qubits. This offers an exponential improvement in circuit depth relative to the number of system qubits, compared to existing methods [1,2] with a circuit depth of $mathcal{O}(n)$. Moreover, in our protocol, the subnormalization, a scaled factor that influences the measurement probability of ancillary qubits, is minimized to $sum_{l=0}^{s_0}vert A_lvert$, where $s_0$ denotes the number of classifications in the dictionary and $A_l$ represents the value of the $l$-th classification. Furthermore, we show that our protocol connects to linear combinations of unitaries $(LCU)$ and the sparse access input model $(SAIM)$. To demonstrate the practical utility of our approach, we provide several applications, including Laplacian matrices in graph problems and discrete differential operators.","PeriodicalId":20807,"journal":{"name":"Quantum","volume":"18 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144677389","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