检索结果-内蒙古大学图书馆

Using models to improve optimizers for variational quantum algorithms

quantum SCIENCE AND TECHNOLOGY 2020年第4期5卷

作者： Sung, Kevin J. Yao, Jiahao Harrigan, Matthew P. Rubin, Nicholas C. Jiang, Zhang Lin, Lin Babbush, Ryan McClean, Jarrod R. Google Res Venice CA 90291 USA Univ Michigan Dept Elect Engn & Comp Sci Ann Arbor MI 48109 USA Univ Calif Berkeley Dept Math Berkeley CA 94720 USA Lawrence Berkeley Natl Lab Computat Res Div Berkeley CA USA

variational quantum algorithms are a leading candidate for early applications on noisy intermediate-scale quantum computers. These algorithms depend on a classical optimization outer-loop that minimizes some function of a parameterized quantum circuit. In practice, finite sampling error and gate errors make this a stochastic optimization with unique challenges that must be addressed at the level of the optimizer. The sharp trade-off between precision and sampling time in conjunction with experimental constraints necessitates the development of new optimization strategies to minimize overall wall clock time in this setting. In this work, we introduce two optimization methods and numerically compare their performance with common methods in use today. The methods are surrogate model-based algorithms designed to improve reuse of collected data. They do so by utilizing a least-squares quadratic fit of sampled function values within a moving trusted region to estimate the gradient or a policy gradient. To make fair comparisons between optimization methods, we develop experimentally relevant cost models designed to balance efficiency in testing and accuracy with respect to cloud quantum computing systems. The results here underscore the need to both use relevant cost models and optimize hyperparameters of existing optimization methods for competitive performance. The methods introduced here have several practical advantages in realistic experimental settings, and we have used one of them successfully in a separately published experiment on Google's Sycamore device.

关键词： quantum algorithms variational quantum algorithms optimization

来源：评论

学校读者我要写书评

暂无评论

Preparing ground states with a broken symmetry with variational quantum algorithms

引用

quantum SCIENCE AND TECHNOLOGY 2021年第3期6卷 035003-035003页

作者： Vogt, Nicolas Zanker, Sebastian Reiner, Jan-Michael Marthaler, Michael Eckl, Thomas Marusczyk, Anika HQS Quantum Simulat GmbH Haid & Neu Str 7 D-76131 Karlsruhe Germany Robert Bosch GmbH Robert Bosch Campus 1 D-71272 Renningen Germany

One of the most promising applications for near term quantum computers is the simulation of physical quantum systems, particularly many-electron systems in chemistry and condensed matter physics. In solid state physics, finding the correct symmetry broken ground state of an interacting electron system is one of the central challenges. To help finding the correct broken symmetries in the thermodynamic limit methods that allow to determine the groundstate of large but finite interacting electron systems are very useful. The variational Hamiltonian ansatz (VHA), a variational hybrid quantum-classical algorithm especially suited for finding the ground state of a solid state system, will in general not prepare a broken symmetry state unless the initial state is chosen to exhibit the correct symmetry. In this work, we discuss three variations of the VHA designed to find the symmetry-breaking groundstate of a finite system close to a transition point between different orders. As a test case we use the two-dimensional Hubbard model where we break the symmetry explicitly by means of external fields coupling to the Hamiltonian and calculate the response to these fields. For the calculation we simulate a gate-based quantum computer and also consider the effects of dephasing noise on the algorithms. We find that two of the three algorithms are in good agreement with the exact solution for the considered parameter range. The third algorithm agrees with the exact solution only for a part of the parameter regime, but is more robust with respect to dephasing compared to the other two algorithms.

关键词： quantum computing variational quantum algorithms symmetry breaking quantum simulation Hubbard model

来源：评论

学校读者我要写书评

暂无评论

Emulating two qubits with a four-level transmon qudit for variational quantum algorithms

引用

quantum SCIENCE AND TECHNOLOGY 2024年第3期9卷 035003-035003页

作者： Cao, Shuxiang Bakr, Mustafa Campanaro, Giulio Fasciati, Simone D. Wills, James Lall, Deep Shteynas, Boris Chidambaram, Vivek Rungger, Ivan Leek, Peter Univ Oxford Dept Phys Clarendon Lab Oxford TW11 0LW England Natl Phys Lab Teddington TW11 0LW England Univ Oxford Dept Mat Parks Rd Oxford OX1 3PH England Thames Valley Sci Pk Oxford Quantum Circuits Reading RG2 9LH England Alice & Bob 49 Bd Gen Martial Valin F-75015 Paris France Rutherford Appleton Lab Natl Quantum Comp Ctr Harwell Campus Didcot OX11 0QX England

Using quantum systems with more than two levels, or qudits, can scale the computational space of quantum processors more efficiently than using qubits, which may offer an easier physical implementation for larger Hilbert spaces. However, individual qudits may exhibit larger noise, and algorithms designed for qubits require to be recompiled to qudit algorithms for execution. In this work, we implemented a two-qubit emulator using a 4-level superconducting transmon qudit for variational quantum algorithm applications and analyzed its noise model. The major source of error for the variational algorithm was readout misclassification error and amplitude damping. To improve the accuracy of the results, we applied error-mitigation techniques to reduce the effects of the misclassification and qudit decay event. The final predicted energy value is within the range of chemical accuracy.

关键词： transmon qudit variational quantum algorithms

来源：评论

学校读者我要写书评

暂无评论

Excited-state molecular dynamics simulation based on variational quantum algorithms

引用

CHEMICAL PHYSICS LETTERS 2023年 816卷

作者： Hirai, Hirotoshi Toyota Cent Res & Dev Labs Inc 41 1 Yokomichi Nagakute Aichi 4801192 Japan

We propose an excited-state molecular dynamics simulation method based on variational quantum algorithms at a computational cost comparable to that of ground-state simulations. We utilize the feature that excited -states can be obtained as metastable states in the restricted variational quantum eigensolver calculation with a hardware-efficient ansatz. To demonstrate the effectiveness of the method, molecular dynamics simulations are performed for the S1 excited-states of H2 and CH2NH molecules. The results are consistent with those of the exact adiabatic simulations in the S1 states, except for the CH2NH system, after crossing the conical intersection, where the proposed method causes a nonadiabatic transition.

关键词： Excited-state Molecular dynamics quantum computers variational quantum algorithms

来源：评论

学校读者我要写书评

暂无评论

Single-component gradient rules for variational quantum algorithms

引用

quantum SCIENCE AND TECHNOLOGY 2022年第3期7卷 035008-035008页

作者： Hubregtsen, Thomas Wilde, Frederik Qasim, Shozab Eisert, Jens Free Univ Berlin Dahlem Ctr Complex Quantum Syst D-14195 Berlin Germany Helmholtz Zentrum Berlin Mat & Energie D-14109 Berlin Germany Fraunhofer Heinrich Hertz Inst D-10587 Berlin Germany

Many near-term quantum computing algorithms are conceived as variational quantum algorithms, in which parameterized quantum circuits are optimized in a hybrid quantum-classical setup. Examples are variational quantum eigensolvers, quantum approximate optimization algorithms as well as various algorithms in the context of quantum-assisted machine learning. A common bottleneck of any such algorithm is constituted by the optimization of the variational parameters. A popular set of optimization methods work on the estimate of the gradient, obtained by means of circuit evaluations. We will refer to the way in which one can combine these circuit evaluations as gradient rules. This work provides a comprehensive picture of the family of gradient rules that vary parameters of quantum gates individually. The most prominent known members of this family are the parameter shift rule (PSR) and the finite differences method. To unite this family, we propose a generalized PSR that expresses all members of the aforementioned family as special cases, and discuss how all of these can be seen as providing access to a linear combination of exact first- and second-order derivatives. We further prove that a PSR with one non-shifted evaluation and only one shifted circuit evaluation does not exist, and introduce a novel perspective for approaching new gradient rules.

关键词： parameter-shift rule variational quantum algorithms gradient descent

来源：评论

学校读者我要写书评

暂无评论

A case study of variational quantum algorithms for a job shop scheduling problem

引用

EPJ quantum TECHNOLOGY 2022年第1期9卷 5-5页

作者： Amaro, David Rosenkranz, Matthias Fitzpatrick, Nathan Hirano, Koji Fiorentini, Mattia Cambridge Quantum Comp Ltd London SW1P 1BX England Cambridge Quantum Comp Ltd Terrington House 13-15 Hills Rd Cambridge CB2 1NL England Nippon Steel Corp Ltd 20-1 Shintomi Futtsu Chiba 2938511 Japan

Combinatorial optimization models a vast range of industrial processes aiming at improving their efficiency. In general, solving this type of problem exactly is computationally intractable. Therefore, practitioners rely on heuristic solution approaches. variational quantum algorithms are optimization heuristics that can be demonstrated with available quantum hardware. In this case study, we apply four variational quantum heuristics running on IBM's superconducting quantum processors to the job shop scheduling problem. Our problem optimizes a steel manufacturing process. A comparison on 5 qubits shows that the recent filtering variational quantum eigensolver (F-VQE) converges faster and samples the global optimum more frequently than the quantum approximate optimization algorithm (QAOA), the standard variational quantum eigensolver (VQE), and variational quantum imaginary time evolution (VarQITE). Furthermore, F-VQE readily solves problem sizes of up to 23 qubits on hardware without error mitigation post processing.

关键词： Combinatorial optimization variational quantum algorithms Heuristics quantum hardware

来源：评论

学校读者我要写书评

暂无评论

Training iterated protocols for distillation of GHZ states with variational quantum algorithms

引用

PHYSICS LETTERS A 2024年 499卷

作者： Rozgonyi, Aron Szechenyi, Gabor Kalman, Orsolya Kiss, Tamas Eotvos Lorand Univ H-1117 Budapest Hungary HUN REN Wigner Res Ctr Phys H-1525 Budapest Hungary

We present optimized distillation schemes for preparing Greenberger-Horne-Zeilinger (GHZ) states. Our approach relies on training variational quantum circuits with white noise affected GHZ states as inputs. Optimizing for a single iteration of the scheme, we find that it is possible to achieve an increased fidelity to the GHZ state, although further iterations decrease the fidelity. The same scheme, acting on coherently distorted pure-state inputs, is effective only in certain special cases. We show that radically different results can be achieved, however, when one optimizes for the output after two iterations of the protocol. In this case, the obtained schemes are more effective in distilling GHZ states from inputs affected by white noise. Moreover, they can also correct several types of coherent pure-state errors.

关键词： GHZ distillation variational quantum algorithms Iterated nonlinear quantum protocols quantum optimization LOCC

来源：评论

学校读者我要写书评

暂无评论

VarSaw: Application-tailored Measurement Error Mitigation for variational quantum algorithms 23

VarSaw: Application-tailored Measurement Error Mitigation fo...

引用

Proceedings of the 28th ACM International Conference on Architectural Support for Programming Languages and Operating Systems, Volume 4

作者： Siddharth Dangwal Gokul Subramanian Ravi Poulami Das Kaitlin N. Smith Jonathan Mark Baker Frederic T. Chong University of Chicago Chicago USA University of Michigan Ann Arbor United States University of Texas at Austin Austin USA Infleqtion Chicago United States University of Texas at Austin Austin United States of America University of Chicago Chicago United States

ISBN: (纸本)9798400703942

For potential quantum advantage, variational quantum algorithms (VQAs) need high accuracy beyond the capability of today's NISQ devices, and thus will benefit from error mitigation. In this work we are interested in mitigating measurement errors which occur during qubit measurements after circuit execution and tend to be the most error-prone operations, especially detrimental to VQAs. Prior work, JigSaw, has shown that measuring only small subsets of circuit qubits at a time and collecting results across all such `subset' circuits can reduce measurement errors. Then, running the entire (`global') original circuit and extracting the qubit-qubit measurement correlations can be used in conjunction with the subsets to construct a high-fidelity output distribution of the original circuit. Unfortunately, the execution cost of JigSaw scales polynomially in the number of qubits in the circuit, and when compounded by the number of circuits and iterations in VQAs, the resulting execution cost quickly turns *** combat this, we propose VarSaw, which improves JigSaw in an application-tailored manner, by identifying considerable redundancy in the JigSaw approach for VQAs: spatial redundancy across subsets from different VQA circuits and temporal redundancy across globals from different VQA iterations. VarSaw then eliminates these forms of redundancy by commuting the subset circuits and selectively executing the global circuits, reducing computational cost (in terms of the number of circuits executed) over naive JigSaw for VQA by 25x on average and up to 1000x, for the same VQA accuracy. Further, it can recover, on average, 45% of the infidelity from measurement errors in the noisy VQA baseline. Finally, it improves fidelity by 55%, on average, over JigSaw for a fixed computational budget. VarSaw can be accessed here: https://***/siddharthdangwal/VarSaw

关键词： quantum computing variational quantum algorithms error mitigation measurement errors noisy intermediate-scale quantum variational quantum eigensolver

来源：评论

学校读者我要写书评

暂无评论

A high-efficiency variational quantum classifier for high-dimensional data

引用

JOURNAL OF SUPERCOMPUTING 2025年第1期81卷 1-20页

作者： Qi, Han Xiao, Sihui Liu, Zhuo Gong, Changqing Gani, Abdullah Shenyang Aerosp Univ Sch Comp Sci & Technol Shenyang 110136 Peoples R China Univ Malaya Fac Comp Sci & Informat Technol Kuala Lumpur 50603 Malaysia

variational quantum algorithms (VQAs) are most promising to show quantum advantages on noisy intermediate-scale quantum devices. variational quantum classifiers (VQCs) are widely applied to classification tasks in the quantum domain. However, VQCs cannot show advantages in high-dimensional data. The large number of features necessitates the use of a significant number of qubits in VQCs. This results in long training time and increases training difficulty, ultimately leading to poor classification performance. In this paper, in order to enhance the ability of VQCs to handle high-dimensional data, a high-efficiency variational quantum classifier (HE-VQC) is proposed. Comparative Qiskit simulations of HE-VQC and four common VQCs were conducted on the UNSW-NB15 dataset. The simulation results show that HE-VQC significantly reduces training time while delivering superior classification performance.

关键词： quantum computing variational quantum algorithms variational quantum classifiers Noisy intermediate-scale quantum

来源：评论

学校读者我要写书评

暂无评论

Boundary treatment for variational quantum simulations of partial differential equations on quantum computers

引用

COMPUTERS & FLUIDS 2025年 288卷

作者： Over, Paul Bengoechea, Sergio Rung, Thomas Clerici, Francesco Scandurra, Leonardo de Villiers, Eugene Jaksch, Dieter Hamburg Univ Technol Inst Fluid Dynam & Ship Theory Schwarzenberg Campus 4 D-21073 Hamburg Germany ENGYS Srl Via Follatoio 12 I-34148 Trieste TS Italy Engys Ltd London SW18 3SX England Univ Hamburg Inst Quantum Phys Luruper Chaussee 149 D-22761 Hamburg Germany Univ Oxford Clarendon Lab Parks Rd Oxford OX1 3PU England

The paper presents a variational quantum algorithm to solve initial-boundary value problems described by second-order partial differential equations. The approach uses hybrid classical/quantum framework that is well suited for quantum computers of the current noisy intermediate-scale quantum era. The partial differential equation is initially translated into an optimal control problem with a modular control-to-state operator (ansatz). The objective function and its derivatives required by the optimizer can efficiently be evaluated on a quantum computer by measuring an ancilla qubit, while the optimization procedure employs classical hardware. The focal aspect of the study is the treatment of boundary conditions, which is tailored to the properties of the quantum hardware using a correction technique. For this purpose, the boundary conditions and the discretized terms of the partial differential equation are decomposed into a sequence of unitary operations and subsequently compiled into quantum gates. The accuracy and gate complexity of the approach are assessed for second-order partial differential equations by classically emulating the quantum hardware. The examples include steady and unsteady diffusive transport equations fora scalar property in combination with various Dirichlet, Neumann, or Robin conditions. The results of this flexible approach display a robust behavior and a strong predictive accuracy in combination with a remarkable polylog complexity scaling in the number of qubits of the involved quantum circuits. Remaining challenges refer to adaptive ansatz strategies that speedup the optimization procedure.

关键词： Computational fluid dynamics variational quantum algorithms quantum computing Boundary conditions

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：