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In recent times, Variational Quantum Circuits (VQC) have been widely adopted to different tasks in machine learning such as Combinatorial Optimization and Supervised Learning. With the growing interest, it is pertinent to study the…

Quantum Physics · Physics 2022-12-13 Dheeraj Peddireddy , Vipul Bansal , Vaneet Aggarwal

This paper presents a quantum algorithm for solving the fractional Poisson equation \((-\Delta)^s u = f\) with \(s \in (0,1)\) on bounded domains. The proposed approach combines rational approximation techniques with quantum linear system…

Quantum Physics · Physics 2026-04-02 Yin Yang , Yue Yu , Long Zhang , Ming Zhou

A universal quantum computer of large scale is not available yet, however, intermediate models of quantum computation would still permit demonstrations of a quantum computational advantage over classical computing and could challenge the…

Quantum Physics · Physics 2024-11-15 Raphael A. Abrahao , Arman Mansouri , Austin P. Lund

Simulating the dynamics and the non-equilibrium steady state of an open quantum system are hard computational tasks on conventional computers. For the simulation of the time evolution, several efficient quantum algorithms have recently been…

Quantum Physics · Physics 2021-02-24 Nathan Ramusat , Vincenzo Savona

We propose the first near-optimal quantum algorithm for estimating in Euclidean norm the mean of a vector-valued random variable with finite mean and covariance. Our result aims at extending the theory of multivariate sub-Gaussian…

Quantum Physics · Physics 2022-07-20 Arjan Cornelissen , Yassine Hamoudi , Sofiene Jerbi

We present and open source a quantum circuit simulator tailored to chemistry applications. More specifically, our simulator can compute the Born-rule probabilities of samples obtained from circuits containing passive fermionic linear…

Dynamic circuits use real-time outcomes of mid-circuit measurements, processed by a classical controller, to adapt subsequent operations during circuit execution. This additional flexibility over static circuits comes at a price.…

Quantum Physics · Physics 2026-05-28 Innocenzo Fulginiti , Yanbin Chen , Christian B. Mendl , Helmut Seidl

Precise device characterization is a fundamental requirement for a large range of applications using photonic hardware, and constitutes a multi-parameter estimation problem. Estimates based on measurements using single photons or classical…

Quantum Physics · Physics 2023-08-24 Nana Liu , Hugo Cable

We introduce an algorithm for the classical simulation of Gaussian boson sampling that is quadratically faster than previously known methods. The complexity of the algorithm is exponential in the number of photon pairs detected, not the…

Approximation algorithms for classical constraint satisfaction problems are one of the main research areas in theoretical computer science. Here we define a natural approximation version of the QMA-complete local Hamiltonian problem and…

Quantum Physics · Physics 2016-10-25 Sevag Gharibian , Julia Kempe

We present a quantum algorithm to solve systems of linear equations of the form $A\mathbf{x}=\mathbf{b}$, where $A$ is a tridiagonal Toeplitz matrix and $\mathbf{b}$ results from discretizing an analytic function, with a circuit complexity…

Quantum Physics · Physics 2022-01-17 Almudena Carrera Vazquez , Ralf Hiptmair , Stefan Woerner

Quantum data loading plays a central role in quantum algorithms and quantum information processing. Many quantum algorithms hinge on the ability to prepare arbitrary superposition states as a subroutine, with claims of exponential speedups…

Quantum Physics · Physics 2025-09-25 Chun-Tse Li , Hao-Chung Cheng

Randomized algorithms for low-rank approximation of quaternion matrices have gained increasing attention in recent years. However, existing methods overlook pass efficiency, the ability to limit the number of passes over the input…

Numerical Analysis · Mathematics 2026-03-25 Salman Ahmadi-Asl , Malihe Nobakht Kooshkghazi , Valentin Leplat

Quantum amplitude estimation is a key sub-routine of a number of quantum algorithms with various applications. We propose an adaptive algorithm for interval estimation of amplitudes. The quantum part of the algorithm is based only on…

Quantum Physics · Physics 2022-06-20 Yunpeng Zhao , Haiyan Wang , Kuai Xu , Yue Wang , Ji Zhu , Feng Wang

Variational quantum algorithms are considered to be appealing applications of near-term quantum computers. However, it has been unclear whether they can outperform classical algorithms or not. To reveal their limitations, we must seek a…

Quantum Physics · Physics 2020-12-15 Kosuke Mitarai , Yasunari Suzuki , Wataru Mizukami , Yuya O. Nakagawa , Keisuke Fujii

Outcome probability estimation via classical methods is an important task for validating quantum computing devices. Outcome probabilities of any quantum circuit can be estimated using Monte Carlo sampling, where the amount of negativity…

Quantum Physics · Physics 2022-10-14 Nikolaos Koukoulekidis , Hyukjoon Kwon , Hyejung H. Jee , David Jennings , M. S. Kim

Quantum algorithms have been developed for efficiently solving linear algebra tasks. However, they generally require deep circuits and hence universal fault-tolerant quantum computers. In this work, we propose variational algorithms for…

Quantum Physics · Physics 2021-12-28 Xiaosi Xu , Jinzhao Sun , Suguru Endo , Ying Li , Simon C. Benjamin , Xiao Yuan

We introduce a variational quantum algorithm to solve unconstrained black box binary optimization problems, i.e., problems in which the objective function is given as black box. This is in contrast to the typical setting of quantum…

We study the impact of experimental imperfections on a recently proposed protocol for performing quantum simulations of vibronic spectroscopy. Specifically, we propose a method for quantifying the impact of these imperfections, optimizing…

Variational hybrid quantum-classical optimization represents one of the most promising avenue to show the advantage of nowadays noisy intermediate-scale quantum computers in solving hard problems, such as finding the minimum-energy state of…

Quantum Physics · Physics 2020-11-18 Laura Gentini , Alessandro Cuccoli , Stefano Pirandola , Paola Verrucchi , Leonardo Banchi