Decomposing complex unitary evolution into a series of constituent components is a cornerstone of practical quantuminformationprocessing. While the decomposition of an n×n unitary into a product of 2×2 sub...
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Decomposing complex unitary evolution into a series of constituent components is a cornerstone of practical quantuminformationprocessing. While the decomposition of an n×n unitary into a product of 2×2 subunitaries (which can for example be realized by beam splitters and phase shifters in linear optics) is well established, we show how for any m>2 this decomposition can be generalized into a product of m×m subunitaries (which can then be realized by a more complex device acting on m modes). If the cost associated with building each m×m multimode device is less than constructing with m(m−1)2 individual 2×2 devices, we show that the decomposition of large unitaries into m×m submatrices is more resource efficient and exhibits a higher tolerance to errors, than its 2×2 counterpart. This allows larger-scale unitaries to be constructed with lower errors, which is necessary for various tasks, not least boson sampling, the quantum Fourier transform, and quantum simulations.
In this paper, we present a generalisation of the Phase Kick-Back technique, which is central to some of the classical algorithms in quantum computing. We will begin by recalling the Phase Kick-Back technique to then ...
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In this paper, we present a generalisation of the Phase Kick-Back technique, which is central to some of the classical algorithms in quantum computing. We will begin by recalling the Phase Kick-Back technique to then introduce the new generalised version for f : {0, 1}(n) ->{0, 1}(m) functions using the eigenvalues of the oracle function U (f). After that, we will present a new generalised version of the Deutsch-Jozsa problem and how it can be solved using the previously defined technique. We will also deal with a generalised version of the Bernstein-Vazirani problem and solve it using the generalised Phase Kick-Back. Finally, we show how we can use this technique to obtain an algorithm for Simon's problem that improves the classical one.
In this letter, we consider the problem of online (real-time, single-shot) estimation of static or slow-varying parameters along quantum trajectories in quantum dynamical systems. Based on the measurement signal of a ...
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In this letter, we consider the problem of online (real-time, single-shot) estimation of static or slow-varying parameters along quantum trajectories in quantum dynamical systems. Based on the measurement signal of a continuously monitored quantum system, we propose a recursive algorithm for computing the maximum likelihood (ML) estimate of unknown parameters using an approach based on stochastic gradient ascent on the log-likelihood function. We formulate the algorithm in both discrete-time and continuous-time and illustrate the performance of the algorithm through simulations of a simple two-level system undergoing homodyne measurement from which we are able to track multiple parameters simultaneously.
As quantum computing technology matures, the availability and performance of quantum devices are steadily improving. However, in the NISQ (Noisy Intermediate-Scale quantum) era, the quantum bit error rate caused by qu...
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This article proposes a benchmark testing set and evaluation system for quantum computers. Our tests do not focus on the topology of quantum computers or the specific implementation details of preparing quantum bits. ...
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This article proposes a benchmark testing set and evaluation system for quantum computers. Our tests do not focus on the topology of quantum computers or the specific implementation details of preparing quantum bits. Instead, we examine the overall performance of quantum computers from the perspective of users. Inspired by traditional computer benchmark tests such as SPECCPU2017, we integrate existing scalable quantum applications and algorithms to generate a testing set that covers algorithms such as search, machine learning, factorization, portfolio optimization, and entanglement state preparation, effectively simulating real workloads. By running the testing set, we can understand the performance of current quantum computers and generate a comprehensive score by combining our evaluation system, which consists of sub-scores of various backend features, including quantum gate error rate, entanglement between quantum bits, cross talk, and connectivity. These sub-scores are calculated based on the program features of the testing cases combined with their running results, where the program features are analyzed through the logical circuits of the testing cases. We incorporate Hellinger fidelity and polarization rescaling into each benchmark to calculate the fidelity of the running results. Through our evaluation system, researchers can be guided toward research directions and understand how far quantum computers are from solving practical problems.
Technological advancements in the 21st century have led to the rise of "big data,"characterized by datasets so vast and complex that traditional database systems struggle to manage them. This term denotes da...
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The crazy, unconscious use of the Internet, and the increase in cybercrime and hacking, which resulted in the loss of a large number of sensitive data, the risk of piracy, etc. were the motivation for protecting right...
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The discrete-logarithm problem and related problems are important in public-key cryptography;however, these problems can be reduced to the hidden-subgroup problem (HSP) of an abelian group, for which efficient quantum...
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The discrete-logarithm problem and related problems are important in public-key cryptography;however, these problems can be reduced to the hidden-subgroup problem (HSP) of an abelian group, for which efficient quantumalgorithms exist. This paper more broadly regards these problems as semigroup-action problems (SAPs) on different modules. The results prove that if the action on a module is injective or the cardinality of the hidden subgroup's least generating set is less than or equal to that of the ring's least generating set, the corresponding SAP on the module can be reduced to the HSP of an abelian group in polynomial time;therefore, most cryptosystems based on the SAP on a module cannot resist quantum cryptanalysis. The results are applicable to the discrete-logarithm problem and matrix-action problem on a group, along with other SAPs on a module. Such reduction is not be found for the SAP on the semi-module. The cryptographic systems based on SAPs on some semi-modules are likely to resist quantum attacks.
quantum computing is an upcoming research area that applies quantum properties of the materials, e.g., superposition and Entanglement, to informationprocessing. The probabilistic nature of this computation allows som...
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ISBN:
(纸本)9798350361513;9798350372304
quantum computing is an upcoming research area that applies quantum properties of the materials, e.g., superposition and Entanglement, to informationprocessing. The probabilistic nature of this computation allows some unique capabilities that are not available in classical computing. quantuminformationprocessing (QIP), the area of computation using quantum devices, promises to speed up computing significantly compared to classical processing. QIP has been extended to Artificial Intelligence / Machine learning (AI/ML.) in what is referred to as quantum Artificial Intelligence (QAI) / quantum Machine Learning (QML). Whereas the classical ML algorithms efficiently identify patterns from datasets, QML tries to implement algorithms that utilize classical computing in handling the datasets and quantum computing for quantum-specific algorithms. In this paper, we attempt to implement QML in Cyber Security. We will demonstrate an advanced method of attack vector recognition using virtual machine memory introspection using quantum neural networks.
Legitimate quantum operations must adhere to principles of quantum mechanics, particularly the requirements of complete positivity and trace preservation. Yet, non-completely positive maps, especially Hermitian-preser...
Legitimate quantum operations must adhere to principles of quantum mechanics, particularly the requirements of complete positivity and trace preservation. Yet, non-completely positive maps, especially Hermitian-preserving maps, play a crucial role in quantuminformation science. Here, we introduce the Hermitian-preserving map exponentiation algorithm, which can effectively simulate the action of an arbitrary Hermitian-preserving map by exponentiating its output, N(rho)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathcal{N}}(\rho )$$\end{document}, into a quantum process, e-iN(rho)t\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${e}<^>{-i{\mathcal{N}}(\rho )t}$$\end{document}. We analyze the sample complexity of this algorithm and prove its optimality in certain cases. Utilizing positive but not completely positive maps, this algorithm provides exponential speedups in entanglement detection and quantification compared to protocols based on single-copy operations. In addition, it facilitates the encoding-free recovery of noiseless quantum states from multiple noisy ones by simulating the inverse map of the corresponding noise channel, providing a new approach to handling quantum noises. This algorithm acts as a building block of large-scale quantumalgorithms and presents a pathway for exploring potential quantum speedups across a wide range of information-processing tasks.
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