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We report an efficient program for computing the eigenvalues and symmetry-adapted eigenvectors of very large quaternionic (or Hermitian skew-Hamiltonian) matrices, using which structure-preserving diagonalization of matrices of dimension N…

Chemical Physics · Physics 2017-03-20 Toru Shiozaki

We introduce two kinds of quantum algorithms to explore microcanonical and canonical properties of many-body systems. The first one is a hybrid quantum algorithm that, given an efficiently preparable state, computes expectation values in a…

Quantum Physics · Physics 2021-05-19 Sirui Lu , Mari Carmen Bañuls , J. Ignacio Cirac

We present a quantum algorithm to solve dynamic programming problems with convex value functions. For linear discrete-time systems with a $d$-dimensional state space of size $N$, the proposed algorithm outputs a quantum-mechanical…

Quantum Physics · Physics 2021-03-18 David Sutter , Giacomo Nannicini , Tobias Sutter , Stefan Woerner

This paper narrows the gap between previous literature on quantum linear algebra and practical data analysis on a quantum computer, formalizing quantum procedures that speed-up the solution of eigenproblems for data representations in…

Quantum Physics · Physics 2022-08-09 Armando Bellante , Alessandro Luongo , Stefano Zanero

The fundamental problem faced in quantum chemistry is the calculation of molecular properties, which are of practical importance in fields ranging from materials science to biochemistry. Within chemical precision, the total energy of a…

Quantum optimization algorithms hold the promise of solving classically hard, discrete optimization problems in practice. The requirement of encoding such problems in a Hamiltonian realized with a finite -- and currently small -- number of…

Quantum Physics · Physics 2023-07-10 Yifeng Rocky Zhu , David Joseph , Cong Ling , Florian Mintert

We apply numerical optimization and linear algebra algorithms for classical computers to the problem of automatically synthesizing algorithms for quantum computers. Using our framework, we apply several common techniques from these…

Numerical Analysis · Mathematics 2025-09-16 Yuxin Huang , Benjamin E. Grossman-Ponemon , David A. B. Hyde

Harrow, Hassidim, and Lloyd showed that for a suitably specified $N \times N$ matrix $A$ and $N$-dimensional vector $\vec{b}$, there is a quantum algorithm that outputs a quantum state proportional to the solution of the linear system of…

Quantum Physics · Physics 2017-12-27 Andrew M. Childs , Robin Kothari , Rolando D. Somma

Search is one of the most commonly used primitives in quantum algorithm design. It is known that quadratic speedups provided by Grover's algorithm are optimal, and no faster quantum algorithms for Search exist. While it is known that at…

Quantum Physics · Physics 2023-06-07 Ansis Rosmanis

A recent breakthrough by Ambainis, Balodis, Iraids, Kokainis, Pr\=usis and Vihrovs (SODA'19) showed how to construct faster quantum algorithms for the Traveling Salesman Problem and a few other NP-hard problems by combining in a novel way…

Quantum Physics · Physics 2020-07-16 Masayuki Miyamoto , Masakazu Iwamura , Koichi Kise , François Le Gall

We give a classical algorithm for linear regression analogous to the quantum matrix inversion algorithm [Harrow, Hassidim, and Lloyd, Physical Review Letters'09, arXiv:0811.3171] for low-rank matrices [Wossnig, Zhao, and Prakash, Physical…

Data Structures and Algorithms · Computer Science 2022-07-06 András Gilyén , Zhao Song , Ewin Tang

This paper studies the problem of selecting a submatrix of a positive definite matrix in order to achieve a desired bound on the smallest eigenvalue of the submatrix. Maximizing this smallest eigenvalue has applications to selecting input…

Systems and Control · Computer Science 2017-09-08 Andrew Clark , Qiqiang Hou , Linda Bushnell , Radha Poovendran

Recently, there has been a surge of interest for quantum computation for its ability to exponentially speed up algorithms, including machine learning algorithms. However, Tang suggested that the exponential speed up can also be done on a…

Discrete Mathematics · Computer Science 2020-12-03 Daniel Chen , Yekun Xu , Betis Baheri , Samuel A. Stein , Chuan Bi , Ying Mao , Qiang Quan , Shuai Xu

Leverage score sampling is crucial to the design of randomized algorithms for large-scale matrix problems, while the computation of leverage scores is a bottleneck of many applications. In this paper, we propose a quantum algorithm to…

Quantum Physics · Physics 2023-09-19 Changpeng Shao

We construct a quantum-inspired classical algorithm for computing the permanent of Hermitian positive semidefinite matrices, by exploiting a connection between these mathematical structures and the boson sampling model. Specifically, the…

Quantum Physics · Physics 2017-09-01 L. Chakhmakhchyan , N. J. Cerf , R. Garcia-Patron

We extend molecular bootstrap embedding to make it appropriate for implementation on a quantum computer. This enables solution of the electronic structure problem of a large molecule as an optimization problem for a composite Lagrangian…

We create a variety of new quantum algorithms that use Grover's algorithm and similar techniques to give polynomial speedups over their classical counterparts. We begin by introducing a set of tools that carefully minimize the impact of…

Quantum Physics · Physics 2007-05-23 Bartholomew Furrow

Quantum algorithms for solving linear systems of equations have generated excitement because of the potential speed-ups involved and the importance of solving linear equations in many applications. However, applying these algorithms can be…

A quantum walk algorithm can detect the presence of a marked vertex on a graph quadratically faster than the corresponding random walk algorithm (Szegedy, FOCS 2004). However, quantum algorithms that actually find a marked element…

Quantum Physics · Physics 2019-03-19 Andris Ambainis , András Gilyén , Stacey Jeffery , Martins Kokainis

We consider the uniform approximation of the smallest eigenvalue of a large parameter-dependent Hermitian matrix by that of a smaller counterpart obtained through projections. The projection subspaces are constructed iteratively by means of…

Numerical Analysis · Mathematics 2026-01-16 Mattia Manucci , Emre Mengi , Nicola Guglielmi