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A hybrid quantum-classical algorithm is a computational scheme in which quantum circuits are used to extract information that is then processed by a classical routine to guide subsequent quantum operations. These algorithms are especially…

Quantum Physics · Physics 2025-09-03 Alon Levi , Ziv Ossi , Eliahu Cohen , Amit Te'eni

We develop randomized quantum algorithms to simulate quantum collision models, also known as repeated interaction schemes, which provide a rich framework to model various open-system dynamics. The underlying technique involves composing…

Quantum Physics · Physics 2025-08-20 Kushagra Garg , Zeeshan Ahmed , Subhadip Mitra , Shantanav Chakraborty

In numerical approaches to solving differential equations on a lattice, a representation of the derivative operator that correctly matches the continuum behaviour of functions of momentum up to the band limit must be non-local. We present…

We present a quantum algorithm for simulating open quantum systems coupled to Gaussian environments valid for any configuration and coupling strength. The algorithm is applicable to problems with strongly coupled, or non-Markovian,…

Quantum Physics · Physics 2025-11-20 Hans Michael Christensen , Johannes Agerskov , Frederik Nathan

Hybrid quantum-classical optimization algorithms represent one of the most promising application for near-term quantum computers. In these algorithms the goal is to optimize an observable quantity with respect to some classical parameters,…

Quantum Physics · Physics 2021-01-27 Leonardo Banchi , Gavin E. Crooks

This article presents the first complete application of a quantum time-marching algorithm for simulating multidimensional linear transport phenomena with arbitrary boundaries, whereby the success probabilities are problem intrinsic. The…

Quantum Physics · Physics 2026-04-13 Sergio Bengoechea , Paul Over , Thomas Rung

We provide a new perspective on non-Hermitian evolution in quantum mechanics by emphasizing the same method as in the Hermitian quantum evolution. We first give a precise description of the non unitary evolution, and collecting the basic…

Quantum Physics · Physics 2017-07-21 Mustapha Maamache

Solving eigenproblem of the Laplacian matrix of a fully connected weighted graph has wide applications in data science, machine learning, and image processing, etc. However, this is very challenging because it involves expensive matrix…

Quantum Physics · Physics 2022-05-31 Hai-Ling Liu , Su-Juan Qin , Lin-Chun Wan , Chao-Hua Yu , Shi-Jie Pan , Fei Gao , Qiao-Yan Wen

Stochastic dynamics of a quantum system driven by $N$ statistically independent random sudden quenches in a fixed time interval is studied. We reveal that with growing $N$ the system approaches a deterministic limit indicating…

Quantum Physics · Physics 2018-08-15 Marcin Łobejko , Jerzy Dajka , Jerzy Łuczka

How well can quantum computers simulate classical dynamical systems? There is increasing effort in developing quantum algorithms to efficiently simulate dynamics beyond Hamiltonian simulation, but so far exact resource estimates are not…

We consider the problem of learning the evolution operator for the time-dependent Schr\"{o}dinger equation, where the Hamiltonian may vary with time. Existing neural network-based surrogates often ignore fundamental properties of the…

Machine Learning · Statistics 2026-04-07 Yash Patel , Unique Subedi , Ambuj Tewari

In this paper we study the time evolution of an observable in the interacting fermion systems driven out of equilibrium. We present a method for solving the Heisenberg equations of motion by constructing excitation operators which are…

Strongly Correlated Electrons · Physics 2013-12-17 Pei Wang

The time-evolution operator obtained from the fractional-time Schr\"{o}dinger equation (FTSE) is said to be non-unitary since it does not preserve the norm of the vector state in time. As done in the time-dependent non-Hermitian quantum…

Quantum Physics · Physics 2022-11-23 D. Cius , L. Menon , M. A. F. dos Santos , A. S. M. de Castro , F. M. Andrade

Imaginary-time evolution plays an important role in algorithms for computing ground-state and thermal equilibrium properties of quantum systems, but can be challenging to simulate on classical computers. Many quantum algorithms for…

Quantum Physics · Physics 2025-07-22 Annie Ray , Esha Swaroop , Ningping Cao , Michael Vasmer , Anirban Chowdhury

All elementary Hamiltonians in nature are expected to be invariant under rotation. Despite this restriction, we usually assume that any arbitrary measurement or unitary time evolution can be implemented on a physical system, an assumption…

Quantum Physics · Physics 2009-11-13 I. Marvian , R. B. Mann

The current generation of noisy intermediate scale quantum computers introduces new opportunities to study quantum many-body systems. In this paper, we show that quantum circuits can provide a dramatically more efficient representation than…

Quantum Physics · Physics 2021-03-24 Sheng-Hsuan Lin , Rohit Dilip , Andrew G. Green , Adam Smith , Frank Pollmann

Machine learning is widely believed to be one of the most promising practical applications of quantum computing. Existing quantum machine learning schemes typically employ a quantum-classical hybrid approach that relies crucially on…

Quantum Physics · Physics 2025-02-11 Qi Ye , Shuangyue Geng , Zizhao Han , Weikang Li , L. -M. Duan , Dong-Ling Deng

We introduce an algorithm to improve the error scaling of product formulas by randomly sampling the generator of their exact error unitary. Our approach takes an arbitrary product formula of time $t$, $S_k(t)$ with error $O(t^{k+1})$ and…

Quantum Physics · Physics 2025-08-26 Lana Mineh , Adrian Chapman , Raul A. Santos

A numerical scheme for solving the time-evolution of wave functions under the time dependent Kohn-Sham equation has been developed. Since the effective Hamiltonian depends on the wave functions, the wave functions and the effective…

Computational Physics · Physics 2009-11-07 Naoki Watanabe , Masaru Tsukada

Linear dissipative differential equation is a fundamental model for a large number of physical systems, such as quantum dynamics with non-Hermitian Hamiltonian, open quantum system dynamics, diffusion process and damped system. In this…

Quantum Physics · Physics 2025-08-22 Gengzhi Yang , Akwum Onwunta , Dong An