Quantum Science and Technology最新文献_第9页

Sequential optimal selections of single-qubit gates in parameterized quantum circuits 参数化量子电路中单量子比特门的顺序优化选择

IF 6.7 2区物理与天体物理

Quantum Science and Technology Pub Date : 2024-05-12 DOI: 10.1088/2058-9565/ad4583

Kaito Wada, Rudy Raymond, Yuki Sato and Hiroshi C Watanabe

{"title":"Sequential optimal selections of single-qubit gates in parameterized quantum circuits","authors":"Kaito Wada, Rudy Raymond, Yuki Sato and Hiroshi C Watanabe","doi":"10.1088/2058-9565/ad4583","DOIUrl":"https://doi.org/10.1088/2058-9565/ad4583","url":null,"abstract":"In variational quantum algorithms, it is important to balance conflicting requirements of expressibility and trainability of a parameterized quantum circuit (PQC). However, appropriate PQC designs are not necessarily trivial. Here, we propose an algorithm for optimizing the PQC structure, where single-qubit gates are sequentially replaced by the optimal ones via diagonalization of a matrix whose elements are evaluated on slightly modified circuits. This replacement leads to a better approximation of target states with limited circuit depth. Furthermore, we clarify the existence of a barren plateau in the sequential optimization in terms of the spectrum concentration of the matrix, which defines the cost landscape with respect to changes in the target gate. Then, we rigorously show the concentration is no faster than polynomials in the number of qubits when an n-qubit PQC depth is using local observables. Finally, numerical experiments are provided to show the convergence of our method which is faster than classical optimizers on both simulators and a real device. Our results provide evidences for sequential optimizers as better alternatives to optimize PQCs on near-term quantum devices.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140915031","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

Analog quantum simulation of partial differential equations 偏微分方程的模拟量子仿真

IF 6.7 2区物理与天体物理

Quantum Science and Technology Pub Date : 2024-05-10 DOI: 10.1088/2058-9565/ad49cf

Shi Jin, Nana Liu

{"title":"Analog quantum simulation of partial differential equations","authors":"Shi Jin, Nana Liu","doi":"10.1088/2058-9565/ad49cf","DOIUrl":"https://doi.org/10.1088/2058-9565/ad49cf","url":null,"abstract":"\u0000 Quantum simulators were originally proposed for simulating one partial differential equation in particular -- Schrodinger's equation. Can quantum simulators also efficiently simulate other partial differential equations? While most computational methods for partial differential equations -- both classical and quantum -- are digital (they must be discretised first), partial differential equations have continuous degrees of freedom. This suggests that an analog representation can be more natural. While digital quantum degrees of freedom are usually described by qubits, the analog or continuous quantum degrees of freedom can be captured by qumodes. Based on a method called Schrodingerisation, we show how to directly map D-dimensional linear partial differential equations onto a (D+1)-qumode quantum system where analog or continuous-variable Hamiltonian simulation on D+1 qumodes can be used. This very simple methodology does not require one to discretise partial differential equations first, and it is not only applicable to linear partial differential equations but also to some nonlinear partial differential equations and systems of nonlinear ordinary differential equations. We show some examples using this method, including the Liouville equation, heat equation, Fokker-Planck equation, Black-Scholes equations, wave equation and Maxwell's equations. We also devise new protocols for linear partial differential equations with random coefficients, important in uncertainty quantification, where it is clear how the analog or continuous-variable framework is most natural. This also raises the possibility that some partial differential equations may be simulated directly on analog quantum systems by using Hamiltonians natural for those quantum systems.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140992118","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: 5

Mode Analysis of Spin Field of Thermal Atomic Ensembles 热原子集合体自旋场的模式分析

IF 6.7 2区物理与天体物理

Quantum Science and Technology Pub Date : 2024-05-09 DOI: 10.1088/2058-9565/ad4912

Weiyi Wang, Mingming Xia, Wei Quan, Kai Wei

{"title":"Mode Analysis of Spin Field of Thermal Atomic Ensembles","authors":"Weiyi Wang, Mingming Xia, Wei Quan, Kai Wei","doi":"10.1088/2058-9565/ad4912","DOIUrl":"https://doi.org/10.1088/2058-9565/ad4912","url":null,"abstract":"\u0000 The spin dynamics in a thermal atomic vapor cell have been investigated thoroughly over the past decades and have proven successful in quantum metrology and memory owing to their long coherent time and manipulation convenience. The existing mean field analysis of spin dynamics among the whole cell is sometimes inaccurate due to the non-uniform of the ensemble and spatial coupling of multi-physical fields interacting with the ensembles. Here we perform mode analysis onto the quasi-continuous spin field including atomic thermal motion to derive Bloch mode equations and obtain corresponding analytical solutions in diffusion regime. We show that the widely used mean field dynamics of thermal gas is a particular case in our solution corresponding to the uniform spatial mode. This mode analysis approach offers a precise method for analyzing the dynamics of the spin ensemble in greater details from a field perspective, enabling the effective determination of spatially non-uniform multi-physical field coupling with the spin ensembles, which cannot be accurately analyzed by the mean field method. Furthermore, this work paves a way to address noises and relaxation mechanisms associated with non-uniform fields and interatomic interactions, which are limiting the further improvement of ultrasensitive spin-based sensors.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140995688","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

On the relevance of weak measurements in dissipative quantum systems 论耗散量子系统中弱测量的相关性

IF 6.7 2区物理与天体物理

Quantum Science and Technology Pub Date : 2024-05-08 DOI: 10.1088/2058-9565/ad420b

Lorena Ballesteros Ferraz, John Martin and Yves Caudano

{"title":"On the relevance of weak measurements in dissipative quantum systems","authors":"Lorena Ballesteros Ferraz, John Martin and Yves Caudano","doi":"10.1088/2058-9565/ad420b","DOIUrl":"https://doi.org/10.1088/2058-9565/ad420b","url":null,"abstract":"We investigate the impact of dissipation, including energy relaxation and decoherence, on weak measurements. While weak measurements have been successful in signal amplification, dissipation can compromise their usefulness. More precisely, we show that in systems with a unique steady state, weak values always converge to an expectation value of the measured observable as dissipation time tends to infinity, in contrast to systems with multiple steady states, where the weak values can remain anomalous, i.e. outside the range of eigenvalues of the observable, even in the limit of an infinite dissipation time. In addition, we propose a method for extracting information about the dissipative dynamics of a system using weak values at short dissipation times. Specifically, we explore the amplification of the dissipation rate in a two-level system and the use of weak values to differentiate between Markovian and non-Markovian dissipative dynamics. We also find that weak measurements operating around a weak atom-cavity coupling can probe the atom dissipation through the weak value of non-Hermitian operators within the rotating-wave approximation of the weak interaction.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140895423","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

Privacy-preserving quantum federated learning via gradient hiding 通过梯度隐藏实现隐私保护的量子联合学习

IF 6.7 2区物理与天体物理

Quantum Science and Technology Pub Date : 2024-05-07 DOI: 10.1088/2058-9565/ad40cc

Changhao Li, Niraj Kumar, Zhixin Song, Shouvanik Chakrabarti and Marco Pistoia

{"title":"Privacy-preserving quantum federated learning via gradient hiding","authors":"Changhao Li, Niraj Kumar, Zhixin Song, Shouvanik Chakrabarti and Marco Pistoia","doi":"10.1088/2058-9565/ad40cc","DOIUrl":"https://doi.org/10.1088/2058-9565/ad40cc","url":null,"abstract":"Distributed quantum computing, particularly distributed quantum machine learning, has gained substantial prominence for its capacity to harness the collective power of distributed quantum resources, transcending the limitations of individual quantum nodes. Meanwhile, the critical concern of privacy within distributed computing protocols remains a significant challenge, particularly in standard classical federated learning (FL) scenarios where data of participating clients is susceptible to leakage via gradient inversion attacks by the server. This paper presents innovative quantum protocols with quantum communication designed to address the FL problem, strengthen privacy measures, and optimize communication efficiency. In contrast to previous works that leverage expressive variational quantum circuits or differential privacy techniques, we consider gradient information concealment using quantum states and propose two distinct FL protocols, one based on private inner-product estimation and the other on incremental learning. These protocols offer substantial advancements in privacy preservation with low communication resources, forging a path toward efficient quantum communication-assisted FL protocols and contributing to the development of secure distributed quantum machine learning, thus addressing critical privacy concerns in the quantum computing era.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140890120","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

Non-Markovian quantum gate set tomography 非马尔可夫量子门集层析技术

IF 6.7 2区物理与天体物理

Quantum Science and Technology Pub Date : 2024-05-06 DOI: 10.1088/2058-9565/ad3d80

Ze-Tong Li, Cong-Cong Zheng, Fan-Xu Meng, Han Zeng, Tian Luan, Zai-Chen Zhang and Xu-Tao Yu

{"title":"Non-Markovian quantum gate set tomography","authors":"Ze-Tong Li, Cong-Cong Zheng, Fan-Xu Meng, Han Zeng, Tian Luan, Zai-Chen Zhang and Xu-Tao Yu","doi":"10.1088/2058-9565/ad3d80","DOIUrl":"https://doi.org/10.1088/2058-9565/ad3d80","url":null,"abstract":"Engineering quantum devices requires reliable characterization of the quantum system, including qubits, quantum operations (also known as instruments) and the quantum noise. Recently, quantum gate set tomography (GST) has emerged as a powerful technique for self-consistently describing quantum states, gates, and measurements. However, non-Markovian correlations between the quantum system and environment impact the reliability of GST. To address this, we propose a self-consistent operational framework called instrument set tomography (IST) for non-Markovian GST. Based on the stochastic quantum process, the instrument set describes instruments and system-environment (SE) correlations. We introduce a linear inversion IST (LIST) to describe instruments and SE correlations without physical constraints. The disharmony of linear relationships between instruments is detected. Furthermore, we propose a physically constrained statistical method based on the maximum likelihood estimation for IST (MLE-IST) with adjustable dimensions. MLE-IST shows significant flexibility in adapting to different types of devices, such as noisy intermediate-scale quantum (NISQ) devices, by adjusting the model and constraints. Experimental results demonstrate the effectiveness and necessity of simultaneously describing instruments and SE correlations. Specifically, the LIST and MLE-IST obtains significant improvement on average square error reduction in the imperfect implemented simulations by orders of −23.77 and −6.21, respectively, compared to their comparative methods. Remarkably, real-chip experiments indicate that a polynomial number of parameters with respect to the Markovian order are sufficient to characterize non-Markovian quantum noise in current NISQ devices. Consequently, IST provides an essential and self-consistent framework for characterizing, benchmarking, and developing quantum devices in terms of the instrument set.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140845761","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

Quantum thermodynamics of boundary time-crystals 边界时间晶体的量子热力学

IF 6.7 2区物理与天体物理

Quantum Science and Technology Pub Date : 2024-05-06 DOI: 10.1088/2058-9565/ad3f42

Federico Carollo, Igor Lesanovsky, Mauro Antezza and Gabriele De Chiara

{"title":"Quantum thermodynamics of boundary time-crystals","authors":"Federico Carollo, Igor Lesanovsky, Mauro Antezza and Gabriele De Chiara","doi":"10.1088/2058-9565/ad3f42","DOIUrl":"https://doi.org/10.1088/2058-9565/ad3f42","url":null,"abstract":"Time-translation symmetry breaking is a mechanism for the emergence of non-stationary many-body phases, so-called time-crystals, in Markovian open quantum systems. Dynamical aspects of time-crystals have been extensively explored over the recent years. However, much less is known about their thermodynamic properties, also due to the intrinsic nonequilibrium nature of these phases. Here, we consider the paradigmatic boundary time-crystal system, in a finite-temperature environment, and demonstrate the persistence of the time-crystalline phase at any temperature. Furthermore, we analyze thermodynamic aspects of the model investigating, in particular, heat currents, power exchange and irreversible entropy production. Our work sheds light on the thermodynamic cost of sustaining nonequilibrium time-crystalline phases and provides a framework for characterizing time-crystals as possible resources for, e.g. quantum sensing. Our results may be verified in experiments, for example with trapped ions or superconducting circuits, since we connect thermodynamic quantities with mean value and covariance of collective (magnetization) operators.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140845847","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

Information flow in parameterized quantum circuits 参数化量子电路中的信息流

IF 6.7 2区物理与天体物理

Quantum Science and Technology Pub Date : 2024-05-06 DOI: 10.1088/2058-9565/ad3eab

Abhinav Anand, Lasse Bjørn Kristensen, Felix Frohnert, Sukin Sim and Alán Aspuru-Guzik

引用次数: 0

Quantum Fourier networks for solving parametric PDEs 用于求解参数 PDE 的量子傅立叶网络

IF 6.7 2区物理与天体物理

Quantum Science and Technology Pub Date : 2024-05-06 DOI: 10.1088/2058-9565/ad42ce

Nishant Jain, Jonas Landman, Natansh Mathur and Iordanis Kerenidis

{"title":"Quantum Fourier networks for solving parametric PDEs","authors":"Nishant Jain, Jonas Landman, Natansh Mathur and Iordanis Kerenidis","doi":"10.1088/2058-9565/ad42ce","DOIUrl":"https://doi.org/10.1088/2058-9565/ad42ce","url":null,"abstract":"Many real-world problems, like modelling environment dynamics, physical processes, time series etc involve solving partial differential equations (PDEs) parameterised by problem-specific conditions. Recently, a deep learning architecture called Fourier neural operator (FNO) proved to be capable of learning solutions of given PDE families for any initial conditions as input. However, it results in a time complexity linear in the number of evaluations of the PDEs while testing. Given the advancements in quantum hardware and the recent results in quantum machine learning methods, we exploit the running efficiency offered by these and propose quantum algorithms inspired by the classical FNO, which result in time complexity logarithmic in the number of evaluations and are expected to be substantially faster than their classical counterpart. At their core, we use the unary encoding paradigm and orthogonal quantum layers and introduce a new quantum Fourier transform in the unary basis. We propose three different quantum circuits to perform a quantum FNO. The proposals differ in their depth and their similarity to the classical FNO. We also benchmark our proposed algorithms on three PDE families, namely Burgers’ equation, Darcy’s flow equation and the Navier–Stokes equation. The results show that our quantum methods are comparable in performance to the classical FNO. We also perform an analysis on small-scale image classification tasks where our proposed algorithms are at par with the performance of classical convolutional neural networks, proving their applicability to other domains as well.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140845914","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

Near-term distributed quantum computation using mean-field corrections and auxiliary qubits 利用均场修正和辅助量子比特的近期分布式量子计算

IF 6.7 2区物理与天体物理

Quantum Science and Technology Pub Date : 2024-05-02 DOI: 10.1088/2058-9565/ad3f45

Abigail McClain Gomez, Taylor L Patti, Anima Anandkumar and Susanne F Yelin

{"title":"Near-term distributed quantum computation using mean-field corrections and auxiliary qubits","authors":"Abigail McClain Gomez, Taylor L Patti, Anima Anandkumar and Susanne F Yelin","doi":"10.1088/2058-9565/ad3f45","DOIUrl":"https://doi.org/10.1088/2058-9565/ad3f45","url":null,"abstract":"Distributed quantum computation is often proposed to increase the scalability of quantum hardware, as it reduces cooperative noise and requisite connectivity by sharing quantum information between distant quantum devices. However, such exchange of quantum information itself poses unique engineering challenges, requiring high gate fidelity and costly non-local operations. To mitigate this, we propose near-term distributed quantum computing, focusing on approximate approaches that involve limited information transfer and conservative entanglement production. We first devise an approximate distributed computing scheme for the time evolution of quantum systems split across any combination of classical and quantum devices. Our procedure harnesses mean-field corrections and auxiliary qubits to link two or more devices classically, optimally encoding the auxiliary qubits to both minimize short-time evolution error and extend the approximate scheme’s performance to longer evolution times. We then expand the scheme to include limited quantum information transfer through selective qubit shuffling or teleportation, broadening our method’s applicability and boosting its performance. Finally, we build upon these concepts to produce an approximate circuit-cutting technique for the fragmented pre-training of variational quantum algorithms. To characterize our technique, we introduce a non-linear perturbation theory that discerns the critical role of our mean-field corrections in optimization and may be suitable for analyzing other non-linear quantum techniques. This fragmented pre-training is remarkably successful, reducing algorithmic error by orders of magnitude while requiring fewer iterations.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140821083","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