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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

Neuroscientists fit morphologically and biophysically detailed neuron simulations to physiological data, often using evolutionary algorithms. However, such gradient-free approaches are computationally expensive, making convergence slow when…

Neurons and Cognition · Quantitative Biology 2024-07-23 Ilenna Simone Jones , Konrad Paul Kording

In this work, the Particle Swarm Optimization (PSO) algorithm has been used to train various Variational Quantum Circuits (VQCs). This approach is motivated by the fact that commonly used gradient-based optimization methods can suffer from…

Quantum Physics · Physics 2025-09-22 Marco Mordacci , Michele Amoretti

Solving linear ordinary differential equations (ODE) is one of the most promising applications for quantum computers to demonstrate exponential advantages. The challenge of designing a quantum ODE algorithm is how to embed non-unitary…

Quantum Physics · Physics 2025-10-30 Zhong-Xia Shang , Naixu Guo , Dong An , Qi Zhao

Reference arXiv:1904.03196 recently introduced an algorithm (QPS) for simulating parton showers with intermediate flavor states using polynomial resources on a digital quantum computer. We make use of a new quantum hardware capability…

High Energy Physics - Phenomenology · Physics 2023-06-27 Plato Deliyannis , James Sud , Diana Chamaki , Zoë Webb-Mack , Christian W. Bauer , Benjamin Nachman

The performance of quantum key distribution (QKD) protocols is evaluated based on the ease of implementation and key generation rate. Among major protocols, the differential-phase-shift (DPS) protocol has the advantage of simple…

Quantum Physics · Physics 2024-12-24 Akihiro Mizutani , Toyohiro Tsurumaru

Quantum Phase Estimation (QPE) is a cornerstone algorithm for fault-tolerant quantum computation, especially for electronic structure calculations of chemical systems. To accommodate the diverse characteristics of quantum chemical systems,…

Quantum Physics · Physics 2025-10-03 Calvin Ku , Yu-Cheng Chen , Alice Hu , Min-Hsiu Hsieh

We define a class of stochastic processes based on evolutions and measurements of quantum systems, and consider the complexity of predicting their long-term behavior. It is shown that a very general class of decision problems regarding…

Computational Complexity · Computer Science 2007-05-23 John Watrous

One significant advantage of superconducting processors is their extensive design flexibility, which encompasses various types of qubits and interactions. Given the large number of tunable parameters of a processor, the ability to perform…

Quantum Physics · Physics 2025-04-25 Ziang Wang , Feng Wu , Hui-Hai Zhao , Xin Wan , Xiaotong Ni

There is a recent surge of interest and insights regarding the interplay of quantum optimal control and variational quantum algorithms. We study the framework in the context of qudits which are, for instance, definable as controllable…

Quantum Physics · Physics 2022-10-26 A. Barış Özgüler , Davide Venturelli

Improving quantum algorithms run-time performance involves several strategies such as reducing the quantum gate counts, decreasing the number of measurements, advancement in QPU technology for faster gate operations, or optimizing the…

Quantum Physics · Physics 2025-07-31 Akhil Francis , Abhi D. Rajagopala , Norm M. Tubman , Katherine Klymko , Kasra Nowrouzi

Quantum chemistry applications on quantum computers currently rely heavily on the variational quantum eigensolver (VQE) algorithm. This hybrid quantum-classical algorithm aims at finding ground state solutions of molecular systems based on…

In this work, we describe a new algorithm, O1NumHess, to calculate the Hessian of a molecular system by finite differentiation of gradients calculated at displaced geometries. Different from the conventional seminumerical Hessian algorithm,…

Chemical Physics · Physics 2025-08-12 Bo Wang , Shaohang Luo , Zikuan Wang , Wenjian Liu

We report some improvements to the gradient ascent pulse engineering (GRAPE) algorithm for optimal control of quantum systems. These include more accurate gradients, convergence acceleration using the BFGS quasi-Newton algorithm as well as…

Quantum Physics · Physics 2014-07-16 P. de Fouquieres , S. G. Schirmer , S. J. Glaser , Ilya Kuprov

Quantum optimal control theory (QOCT) can be used to design the shape of electromagnetic pulses that implement operations on quantum devices. By using non-trivially shaped waveforms, gates can be made significantly faster than those built…

Quantum Physics · Physics 2026-02-27 Alonso Hernández-Antón , Fernando Luis , Alberto Castro

Considering generating samples with high rewards, we focus on optimizing deep neural networks parameterized stochastic differential equations (SDEs), the advanced generative models with high expressiveness, with policy gradient, the leading…

Machine Learning · Computer Science 2024-06-27 Xiangxin Zhou , Liang Wang , Yichi Zhou

With a finite amount of measurement data acquired in variational quantum algorithms, the statistical benefits of several optimized numerical estimation schemes, including the scaled parameter-shift (SPS) rule and finite-difference (FD)…

Quantum Physics · Physics 2024-08-07 Yong Siah Teo

Pulses to steer the time evolution of quantum systems can be designed with optimal control theory. In most cases it is the coherent processes that can be controlled and one optimizes the time evolution towards a target unitary process,…

Quantum Physics · Physics 2015-06-22 Daniel J. Egger , Frank K. Wilhelm

In the burgeoning field of quantum computing, the precise design and optimization of quantum pulses are essential for enhancing qubit operation fidelity. This study focuses on refining the pulse engineering techniques for superconducting…

Quantum Physics · Physics 2024-09-13 Annika S. Wiening , Joern Bergendahl , Vicente Leyton-Ortega , Peter Nalbach

We present a novel method for determining gradients of parameterised quantum circuits (PQCs) in hybrid quantum-classical machine learning models by applying the multivariate version of the simultaneous perturbation stochastic approximation…

Quantum Physics · Physics 2022-11-28 Thomas Hoffmann , Douglas Brown