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Cyclic measurements and simplified quantum state tomography 循环测量和简化量子态层析成像

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-06-04 DOI: 10.22331/q-2025-06-04-1763

Victor Gonzalez Avella, Jakub Czartowski, Dardo Goyeneche, Karol Życzkowski

引用次数: 0

Full Characterization of the Depth Overhead for Quantum Circuit Compilation with Arbitrary Qubit Connectivity Constraint 任意量子比特连通性约束下量子电路编译深度开销的全面表征

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-05-28 DOI: 10.22331/q-2025-05-28-1757

Pei Yuan, Shengyu Zhang

引用次数: 0

Reinforcement Learning Based Quantum Circuit Optimization via ZX-Calculus 基于zx -微积分的强化学习量子电路优化

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-05-28 DOI: 10.22331/q-2025-05-28-1758

Jordi Riu, Jan Nogué, Gerard Vilaplana, Artur Garcia-Saez, Marta P. Estarellas

{"title":"Reinforcement Learning Based Quantum Circuit Optimization via ZX-Calculus","authors":"Jordi Riu, Jan Nogué, Gerard Vilaplana, Artur Garcia-Saez, Marta P. Estarellas","doi":"10.22331/q-2025-05-28-1758","DOIUrl":"https://doi.org/10.22331/q-2025-05-28-1758","url":null,"abstract":"We propose a novel Reinforcement Learning (RL) method for optimizing quantum circuits using graph-theoretic simplification rules of ZX-diagrams. The agent, trained using the Proximal Policy Optimization (PPO) algorithm, employs Graph Neural Networks to approximate the policy and value functions. We demonstrate the capacity of our approach by comparing it against the best performing ZX-Calculus-based algorithm for the problem in hand. After training on small Clifford+T circuits of 5-qubits and few tenths of gates, the agent consistently improves the state-of-the-art for this type of circuits, for at least up to 80-qubit and 2100 gates, whilst remaining competitive in terms of computational performance. Additionally, we illustrate the versatility of the agent by incorporating additional optimization routines on the workflow during training, improving the two-qubit gate count state-of-the-art on multiple structured quantum circuits for relevant applications of much larger dimension and different gate distributions than the circuits the agent trains on. This conveys the potential of tailoring the reward function to the specific characteristics of each application and hardware backend. Our approach is a valuable tool for the implementation of quantum algorithms in the near-term intermediate-scale range (NISQ).","PeriodicalId":20807,"journal":{"name":"Quantum","volume":"11 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144165063","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

The State Preparation of Multivariate Normal Distributions using Tree Tensor Network 基于树张量网络的多元正态分布状态准备

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-05-28 DOI: 10.22331/q-2025-05-28-1755

Hidetaka Manabe, Yuichi Sano

引用次数: 0

Renormalisation of Quantum Cellular Automata 量子元胞自动机的重整化

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-05-28 DOI: 10.22331/q-2025-05-28-1756

Lorenzo Siro Trezzini, Alessandro Bisio, Paolo Perinotti

引用次数: 0

Operational verification of the existence of a spacetime manifold 时空流形存在的操作验证

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-05-22 DOI: 10.22331/q-2025-05-22-1753

Nikola Paunkovic, Marko Vojinovic

引用次数: 0

Protecting information in a parametrically driven hybrid quantum system 参数驱动混合量子系统中的信息保护

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-05-22 DOI: 10.22331/q-2025-05-22-1754

Siddharth Tiwary, Harsh Sharma, Himadri Shekhar Dhar

引用次数: 0

Rise of conditionally clean ancillae for efficient quantum circuit constructions 高效量子电路结构的条件清洁辅助装置的兴起

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-05-21 DOI: 10.22331/q-2025-05-21-1752

Tanuj Khattar, Craig Gidney

{"title":"Rise of conditionally clean ancillae for efficient quantum circuit constructions","authors":"Tanuj Khattar, Craig Gidney","doi":"10.22331/q-2025-05-21-1752","DOIUrl":"https://doi.org/10.22331/q-2025-05-21-1752","url":null,"abstract":"We introduce conditionally clean ancilla qubits, a new quantum resource, recently explored by [17], that bridges the gap between traditional clean and dirty ancillae. Like dirty ancillae, they begin and end in an unknown state and can be borrowed from existing system qubits, avoiding the space overhead of explicit qubit allocation. Like clean ancillae, they can be treated as initialized in a known state within specific computations, thus avoiding the overhead of toggle detection required for dirty ancillae. We present new circuit constructions leveraging conditionally clean ancillae to achieve lower gate counts and depths, particularly with limited ancilla availability. Specifically, we provide constructions for: \u0000 (a) $n$-controlled NOT using $2n$ Toffolis and $O(log{n})$ depth given 2 clean ancillae. (b) $n$-qubit incrementer using $3n$ Toffolis given $log_2^*{n}$ clean ancillae. (c) $n$-qubit quantum-classical comparator using $3n$ Toffolis given $log_2^*{n}$ clean ancillae. (d) unary iteration over $[0,N)$ using $2.5N$ Toffolis given $log_2^*{n}$ clean ancillae. (e) unary iteration via skew tree over $[0, N)$ using $1.25N$ Toffolis given $n$ dirty ancillae. \u0000 We also introduce $textit{laddered toggle detection}$, a technique to replace clean ancillae with dirty ancillae in all our constructions, incurring a 2x Toffoli gate overhead. Our results demonstrate that conditionally clean ancillae are a valuable tool for quantum circuit design, especially in the resource-constrained early fault-tolerant era.","PeriodicalId":20807,"journal":{"name":"Quantum","volume":"19 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144104723","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

Classical Benchmarks for Variational Quantum Eigensolver Simulations of the Hubbard Model 哈伯德模型变分量子特征解算器模拟的经典基准

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-05-20 DOI: 10.22331/q-2025-05-20-1748

Antonios M. Alvertis, Abid Khan, Thomas Iadecola, Peter P. Orth, Norm Tubman

{"title":"Classical Benchmarks for Variational Quantum Eigensolver Simulations of the Hubbard Model","authors":"Antonios M. Alvertis, Abid Khan, Thomas Iadecola, Peter P. Orth, Norm Tubman","doi":"10.22331/q-2025-05-20-1748","DOIUrl":"https://doi.org/10.22331/q-2025-05-20-1748","url":null,"abstract":"Simulating the Hubbard model is of great interest to a wide range of applications within condensed matter physics, however its solution on classical computers remains challenging in dimensions larger than one. The relative simplicity of this model, embodied by the sparseness of the Hamiltonian matrix, allows for its efficient implementation on quantum computers, and for its approximate solution using variational algorithms such as the variational quantum eigensolver. While these algorithms have been shown to reproduce the qualitative features of the Hubbard model, their quantitative accuracy in terms of producing true ground state energies and other properties, and the dependence of this accuracy on the system size and interaction strength, the choice of variational ansatz, and the degree of spatial inhomogeneity in the model, remains unknown. Here we present a rigorous classical benchmarking study, demonstrating the potential impact of these factors on the accuracy of the variational solution of the Hubbard model on quantum hardware, for systems with up to $32$ qubits. We find that even when using the most accurate wavefunction ansÃ¤tze for the Hubbard model, the error in its ground state energy and wavefunction plateaus for larger lattices, while stronger electronic correlations magnify this issue. Concurrently, spatially inhomogeneous parameters and the presence of off-site Coulomb interactions only have a small effect on the accuracy of the computed ground state energies. Our study highlights the capabilities and limitations of current approaches for solving the Hubbard model on quantum hardware, and we discuss potential future avenues of research.","PeriodicalId":20807,"journal":{"name":"Quantum","volume":"73 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144097665","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

Transfer and routing of Gaussian states through quantum complex networks with and without community structure 具有和不具有社团结构的量子复杂网络中高斯态的传输和路由

IF 6.4 2区物理与天体物理

Quantum Pub Date : 2025-05-20 DOI: 10.22331/q-2025-05-20-1751

Markku Hahto, Johannes Nokkala, Guillermo García-Pérez, Sabrina Maniscalco, Jyrki Piilo

{"title":"Transfer and routing of Gaussian states through quantum complex networks with and without community structure","authors":"Markku Hahto, Johannes Nokkala, Guillermo García-Pérez, Sabrina Maniscalco, Jyrki Piilo","doi":"10.22331/q-2025-05-20-1751","DOIUrl":"https://doi.org/10.22331/q-2025-05-20-1751","url":null,"abstract":"The goal in quantum state transfer is to avoid the need to physically transport carriers of quantum information. This is achieved by using a suitably engineered Hamiltonian that induces the transfer of the state of one subsystem to another. A less known generalization of state transfer considers multiple systems such that any pair can exchange quantum information and transfers can take place at any time, starting and stopping independently. This is sometimes called routing of quantum states. State transfer in particular has received a great deal of attention, however the vast majority of results in both state transfer and routing concern qubits transferred in a network of restricted structure. Here we consider routing of single-mode Gaussian states and entanglement through complex networks of quantum harmonic oscillators. We compare a protocol where the transfer is completed in a single step but the effective Hamiltonian only approximately transfers the state with one where the transfer can in principle be perfect but the transfer is done in two steps, and also illustrate the state-dependency of the transfer fidelity. We find that even in a random and homogeneous network, the transfer fidelity still depends on the degree of the nodes for any link density, and that in both random and complex networks it is the community structure that controls the appearance of higher frequency normal modes useful for transfer. Finally, we find that networks of sufficient complexity may have superior routing performance over superficially similar random networks. Our results pave the way for further exploration of the role of community structure in state transfer and related tasks.","PeriodicalId":20807,"journal":{"name":"Quantum","volume":"35 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144104722","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