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Gaussian building blocks are essential for photonic quantum information processing, and universality can be practically achieved by equipping Gaussian circuits with adaptive measurement and feedforward. The number of adaptive steps then…

Quantum Physics · Physics 2026-02-17 Changhun Oh , Youngrong Lim

Variational quantum algorithms are a class of techniques intended to be used on near-term quantum computers. The goal of these algorithms is to perform large quantum computations by breaking the problem down into a large number of shallow…

Quantum Physics · Physics 2023-03-24 Ryan Shaffer , Lucas Kocia , Mohan Sarovar

Symmetries are crucial for tailoring parametrized quantum circuits to applications, due to their capability to capture the essence of physical systems. In this work, we shift the focus away from incorporating symmetries in the circuit…

Quantum Physics · Physics 2023-12-13 David Wierichs , Richard D. P. East , Martín Larocca , M. Cerezo , Nathan Killoran

Quantum sensing is an important application of emerging quantum technologies. We explore whether a hybrid system of quantum sensors and quantum circuits can surpass the classical limit of sensing. In particular, we use optimization…

Here we show how universal quantum computers based on the quantum circuit model can handle mathematical analysis calculations for functions with continuous domains, without any digitalization, and with remarkably few qubits. The basic…

Quantum Physics · Physics 2022-10-10 Pablo Bermejo , Roman Orus

A key component of variational quantum algorithms (VQAs) is the choice of classical optimizer employed to update the parameterization of an ansatz. It is well recognized that quantum algorithms will, for the foreseeable future, necessarily…

Quantum Physics · Physics 2025-05-06 Jeffrey Larson , Matt Menickelly , Jiahao Shi

Currently, quantum hardware is restrained by noises and qubit numbers. Thus, a quantum virtual machine that simulates operations of a quantum computer on classical computers is a vital tool for developing and testing quantum algorithms…

Quantum Physics · Physics 2022-06-10 Chuong Nguyen Quoc , Le Bin Ho , Lan Nguyen Tran , Hung Q. Nguyen

Variational quantum algorithms are promising applications of noisy intermediate-scale quantum (NISQ) computers. These algorithms consist of a number of separate prepare-and-measure experiments that estimate terms in a Hamiltonian. The…

Quantum Physics · Physics 2020-06-25 Andrew Zhao , Andrew Tranter , William M. Kirby , Shu Fay Ung , Akimasa Miyake , Peter Love

Quantum computing uses the physical principles of very small systems to develop computing platforms which can solve problems that are intractable on conventional supercomputers. There are challenges not only in building the required…

Quantum Physics · Physics 2024-11-19 Dieter Jaksch , Peyman Givi , Andrew J. Daley , Thomas Rung

Quantum computers are not yet up to the task of providing computational advantages for practical stochastic diffusion models commonly used by financial analysts. In this paper we introduce a class of stochastic processes that are both…

Quantum Physics · Physics 2023-11-03 Eric Ghysels , Jack Morgan , Hamed Mohammadbagherpoor

Variational quantum algorithms (VQAs) are a modern family of quantum algorithms designed to solve optimization problems using a quantum computer. Typically VQAs rely on a feedback loop between the quantum device and a classical optimization…

Quantum Physics · Physics 2022-08-26 Alexey Uvarov

Efficient optimization of quantum systems is a necessity for reaching fault tolerant thresholds. A standard tool for optimizing simulated quantum dynamics is the gradient-based \textsc{grape} algorithm, which has been successfully applied…

Quantum Physics · Physics 2020-10-28 Mogens Dalgaard , Felix Motzoi , Jesper Hasseriis Mohr Jensen , Jacob Sherson

We examine a particular realization of derivative-free method as implemented on tensor train based optimization to the variational quantum eigensolver. As an example, we consider parametrized quantum circuits composed of a low-depth…

Quantum Physics · Physics 2023-06-06 Georgii Paradezhenko , Anastasiia Pervishko , Dmitry Yudin

Several quantities of interest in quantum information, including entanglement and purity, are nonlinear functions of the density matrix and cannot, even in principle, correspond to proper quantum observables. Any method aimed to determine…

Quantum Physics · Physics 2009-08-25 Matteo G. A. Paris

In this proceedings we present quantum machine learning optimization experiments using stochastic gradient descent with the parameter shift rule algorithm. We first describe the gradient evaluation algorithm and its optimization procedure…

Quantum Physics · Physics 2022-10-21 Matteo Robbiati , Stavros Efthymiou , Andrea Pasquale , Stefano Carrazza

Universal fault-tolerant quantum computers will require error-free execution of long sequences of quantum gate operations, which is expected to involve millions of physical qubits. Before the full power of such machines will be available,…

Variational Quantum Algorithms are among the most promising systems to implement quantum computing under the Noisy-Intermediate Scale Quantum (NISQ) technology. In variational quantum algorithm, wavefunction represented by a parametrized…

Quantum Physics · Physics 2023-01-02 H. Davoodi Yeganeh

Hybrid classical quantum optimization methods have become an important tool for efficiently solving problems in the current generation of NISQ computers. These methods use an optimization algorithm executed in a classical computer, fed with…

Quantum Physics · Physics 2023-08-02 J. Gidi , B. Candia , A. D. Muñoz-Moller , A. Rojas , L. Pereira , M. Muñoz , L. Zambrano , A. Delgado

We simulate the effects of different types of noise in state preparation circuits of variational quantum algorithms. We first use a variational quantum eigensolver to find the ground state of a Hamiltonian in presence of noise, and adopt…

Quantum Physics · Physics 2021-08-11 Enrico Fontana , Nathan Fitzpatrick , David Muñoz Ramo , Ross Duncan , Ivan Rungger

Pricing a multi-asset derivative is an important problem in financial engineering, both theoretically and practically. Although it is suitable to numerically solve partial differential equations to calculate the prices of certain types of…

Quantum Physics · Physics 2022-07-05 Kenji Kubo , Koichi Miyamoto , Kosuke Mitarai , Keisuke Fujii