作者:
Tani, SeiichiroNTT Corp
NTT Commun Sci Labs 3-1 Morinosato Wakamiya Atsugi 2430198 Japan Waseda Univ
1-6-1 Nishiwaseda Tokyo Tokyo 1698050 Japan
An ordered binary decision diagram (OBDD) is a directed acyclic graph representing a Boolean function. Since OBDDs have many nice properties as data structures, they have been extensively studied for decades in theore...
详细信息
An ordered binary decision diagram (OBDD) is a directed acyclic graph representing a Boolean function. Since OBDDs have many nice properties as data structures, they have been extensively studied for decades in theoretical and practical fields, such as VLSI (Very Large Scale Integration) design, formal verification, machine learning, and combinatorial problems. Arguably, the most crucial problem in using OBDDs is that they may vary exponentially in size depending on their variable ordering (i.e., the order in which the variables are to be read) when they represent the same function. Indeed, it is NP-hard to find an optimal variable ordering that minimizes an OBDD for a given function. Friedman and Supowit provided a clever deterministic algorithm with time/space complexity O & lowast;(3 degrees), where degrees is the number of variables of the function, which is much better than the trivial brute-force bound O & lowast;(degrees!2 degrees). This paper shows that a further speedup is possible with quantum computers by presenting a quantum algorithm that produces a minimum OBDD together with the corresponding variable ordering in O & lowast;(2.77286 degrees) time and space with an exponentially small error probability. Moreover, this algorithm can be adapted to constructing other minimum decision diagrams, such as zero-suppressed BDDs (ZBDDs or ZDDs).
In this paper, the authors give quantum algorithms for two fundamental computation problems: Solving polynomial systems over finite fields and optimization where the arguments of the objective function and constraints...
详细信息
In this paper, the authors give quantum algorithms for two fundamental computation problems: Solving polynomial systems over finite fields and optimization where the arguments of the objective function and constraints take values from a finite field or a bounded interval of integers. The quantum algorithms can solve these problems with any given success probability and have polynomial runtime complexities in the size of the input, the degree of the inequality constraints, and the condition number of the associated matrices of the problem. So, the authors achieve exponential speedup for these problems when their condition numbers are small. As applications, quantum algorithms are given to three basic computational problems in cryptography: The short integer solution problem, the shortest vector problem, the polynomial system with noise problem, and cryptanalysis for the lattice-based NTRU cryptosystem. It is shown that these problems and NTRU can against quantum computer attacks only if their condition numbers are large, so the condition number could be used as a new criterion for lattice-based post-quantum cryptosystems.
Derandomization is the process of taking a randomized algorithm and turning it into a deterministic algorithm, which has attracted great attention in classical computing. In quantum computing, it is challenging and in...
详细信息
Derandomization is the process of taking a randomized algorithm and turning it into a deterministic algorithm, which has attracted great attention in classical computing. In quantum computing, it is challenging and intriguing to derandomize quantum algorithms, due to the inherent randomness of quantum mechanics. The significance of derandomizing quantum algorithms lies not only in theoretically proving that the success probability can essentially be 1 without sacrificing quantum speedups, but also in experimentally improving the success rate when the algorithm is implemented on a real quantum computer. In this paper, we focus on derandomizing quantum algorithms for the triangle sum problem (including the famous triangle finding problem as a special case), which asks to find a triangle in an edge-weighted graph with n vertices, such that its edges sum up to a given weight. We show that when the graph is promised to contain at most one target triangle, there exists a deterministic quantum algorithm that either finds the triangle if it exists or outputs "no triangle" if none exists. It makes O(n9/7) queries to the edge weight matrix oracle, and thus has the same complexity as the state-of-the-art boundederror quantum algorithm. To achieve this derandomization, we make full use of several techniques: nested quantum walk with quantum data structure, deterministic quantum search with adjustable parameters, and dimensional reduction of quantum walk search on Johnson graph. (c) 2025 Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
Imaginary-time evolution is a powerful tool for obtaining the ground state of a quantum system, but the complexity of classical algorithms designed for simulating imaginary-time evolution will increase significantly a...
详细信息
Imaginary-time evolution is a powerful tool for obtaining the ground state of a quantum system, but the complexity of classical algorithms designed for simulating imaginary-time evolution will increase significantly as the size of the quantum system becomes larger. Here, a probabilistic quantum algorithm based on Taylor expansion for implementing imaginary-time evolution is introduced. For Hamiltonians composed of Pauli product terms, the quantum circuit requires only a single ancillary qubit and is exclusively constructed using elementary single-qubit and two-qubit gates. Furthermore, similar principles are used to extend the algorithm to the case where the Hamiltonian takes a more general form. The algorithm only requires negligible precomputed numerical calculations, without the need for complex classical pre-mathematical calculations or optimization loops. We demonstrate the algorithm by solving the ground state energy of hydrogen molecules and Heisenberg Hamiltonians. Moreover, we conducted experiments on real quantum computers through the quantum cloud platform to find the ground state energy of Heisenberg Hamiltonians. Our work extends the methods for realizing imaginary-time evolution on quantum computers, and our algorithm exhibits potential for implementation on near-term quantum devices, particularly when the Hamiltonian consists of Pauli product terms.
In accord with imaging mechanism, by tackling the integrated quantum circuit without multiple preparations and measurements, a quantum algorithm with remarkable speedup for synthetic aperture radar (SAR) imaging is pr...
详细信息
In accord with imaging mechanism, by tackling the integrated quantum circuit without multiple preparations and measurements, a quantum algorithm with remarkable speedup for synthetic aperture radar (SAR) imaging is proposed to decrease the data storage and time consuming in this letter. First, the quantum algorithms for 2-D matched filtering and range cell migration correction (RCMC) are presented. Then, the relevant quantum circuits are designed and bonded together as an integrated quantum circuit for SAR imaging. It would be further applied to wide-swath imaging and sparse-driven radar imaging to form the corresponding quantum algorithm from quantum data to quantum data. The polynomial speedup in computational complexity is analyzed theoretically, and the needed quantum data are reduced exponentially compared to classical data. Experimental results obtained by computer simulation of quantum algorithm demonstrate that the proposed method can obtain the high-resolution SAR image and decrease at least 10(2) orders in complexity.
quantum phase estimation (QPE) is a key ingredient to some of the most important results of quantum computing. In this paper we examine the QPE algorithm through the looking glass of signal processing. This perspectiv...
详细信息
ISBN:
(数字)9798350368741
ISBN:
(纸本)9798350368758
quantum phase estimation (QPE) is a key ingredient to some of the most important results of quantum computing. In this paper we examine the QPE algorithm through the looking glass of signal processing. This perspective helps to reveal a relation between the distribution of quantum phase estimates and the shape of the discrete Fourier transform (DFT) of a pure complex sinusoid. Guided by spectral shaping theory, we design a class of quantum circuits that are the quantum equivalents to classical windowing operators, for a family of window functions that have compact support in the DFT. These circuits have complexity linear in the number of target qubits, strictly lower than QPE itself. Using these circuits we are able to reshape QPE's performance characteristics. In particular, the asymptotic marginal cost for 2x reduction in fail rate (2x improvement in reliability) is reduced from one qubit to 1/3 qubit or lower, which can help reduce the qubit budget for a preset accuracy-reliability target, especially in high-reliability scenarios. This makes a demonstration of the value of signal processing principles in designing quantum algorithms.
quantum search algorithms, such as Grover's algorithm, are anticipated to efficiently solve constrained combinatorial optimization problems. However, applying these algorithms to the traveling salesman problem (TS...
详细信息
quantum search algorithms, such as Grover's algorithm, are anticipated to efficiently solve constrained combinatorial optimization problems. However, applying these algorithms to the traveling salesman problem (TSP) on a quantum circuit presents a significant challenge. Existing quantum search algorithms for the TSP typically assume that an initial state-an equal superposition of all feasible solutions satisfying the problem's constraints-is pre-prepared. The query complexity of preparing this state using brute-force methods scales exponentially with the factorial growth of feasible solutions, creating a significant hurdle in designing quantum circuits for large-scale TSPs. To address this issue, we propose a two-step quantum search (TSQS) algorithm that employs two sets of operators. In the first step, all the feasible solutions are amplified into their equal superposition state. In the second step, the optimal solution state is amplified from this superposition state. The TSQS algorithm demonstrates greater efficiency compared to conventional search algorithms that employ a single oracle operator for finding a solution within the encoded space. Encoded in the higher order unconstrained binary optimization representation, our approach significantly reduces the qubit requirements. This enables efficient initial state preparation through a unified circuit design, offering a quadratic speedup in solving the TSP without prior knowledge of feasible solutions.
Neighborhood preserving embedding(NPE)is an important linear dimensionality reduction technique that aims at preserving the local manifold *** contains three steps,i.e.,finding the nearest neighbors of each data point...
详细信息
Neighborhood preserving embedding(NPE)is an important linear dimensionality reduction technique that aims at preserving the local manifold *** contains three steps,i.e.,finding the nearest neighbors of each data point,constructing the weight matrix,and obtaining the transformation *** et *** a variational quantum algorithm(VQA)for NPE[***.A 101032323(2020)].The algorithm consists of three quantum sub-algorithms,corresponding to the three steps of NPE,and was expected to have an exponential speedup on the dimensionality ***,the algorithm has two disadvantages:(i)It is not known how to efficiently obtain the input of the third sub-algorithm from the output of the second one.(ii)Its complexity cannot be rigorously analyzed because the third sub-algorithm in it is a *** this paper,we propose a complete quantum algorithm for NPE,in which we redesign the three sub-algorithms and give a rigorous complexity *** is shown that our algorithm can achieve a polynomial speedup on the number of data points m and an exponential speedup on the dimensionality n under certain conditions over the classical NPE algorithm,and achieve a significant speedup compared to Liang et al.’s algorithm even without considering the complexity of the VQA.
Using quantum algorithms to solve various problems has attracted widespread attention with the development of quantum *** are particularly interested in using the acceleration properties of quantum algorithms to solve...
详细信息
Using quantum algorithms to solve various problems has attracted widespread attention with the development of quantum *** are particularly interested in using the acceleration properties of quantum algorithms to solve NP-complete *** paper focuses on the well-known NP-complete problem of finding the minimum dominating set in undirected *** expedite the search process,a quantum algorithm employing Grover’s search is ***,a challenge arises from the unknown number of solutions for the minimum dominating set,rendering direct usage of original Grover’s search ***,a swap test method is introduced to ascertain the number of iterations *** oracle,diffusion operators,and swap test are designed with achievable quantum *** query complexity is O(1.414^(n))and the space complexity is O(n).To validate the proposed approach,qiskit software package is employed to simulate the quantum circuit,yielding the anticipated results.
In scientific computing, one can find a wide application of the matrix-vector product f (A)b. Recently, a quantum algorithm that computes the state | f > corresponding to f (A)b has been proposed in Takahira et al....
详细信息
In scientific computing, one can find a wide application of the matrix-vector product f (A)b. Recently, a quantum algorithm that computes the state | f > corresponding to f (A)b has been proposed in Takahira et al. (quantum Inf Comput 20(1/2):14-36, 2020). However, this important algorithm can not be directly applied to the matrix logarithm, which is one of the significant matrix functions. In this paper, we propose an original quantum algorithm to compute the state | f > = log(A)|b >/|| log(A)|b >/||, via the integral representation of log(A) and the Gauss-Legendre quadrature rule, using LCU method and block-encoding technique as subroutines.
暂无评论