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Ultrafast dynamics in chemical systems provide a unique access to fundamental processes at the molecular scale. A proper description of such systems is often very challenging because of the quantum nature of the problem. The concept of…

Chemical Physics · Physics 2019-04-11 Lars-Hendrik Frahm , Daniela Pfannkuche

This work presents a novel realization approach to Quantum Boltzmann Machines (QBMs). The preparation of the required Gibbs states, as well as the evaluation of the loss function's analytic gradient is based on Variational Quantum Imaginary…

Quantum Physics · Physics 2021-03-01 Christa Zoufal , Aurélien Lucchi , Stefan Woerner

To compute approximate solutions for combinatorial optimization problems, we describe variational methods based on the product state (PS) and matrix product state (MPS) ansatzes. We perform variational energy minimization with respect to a…

Quantum Physics · Physics 2025-12-24 Guillermo Preisser , Conor Mc Keever , Michael Lubasch

Matrix Product States (MPS) and Operators (MPO) have been proven to be a powerful tool to study quantum many-body systems but are restricted to moderately entangled states as the number of parameters scales exponentially with the…

Most quantum algorithms designed to generate or probe properties of the ground state of a quantum many-body system require as input an initial state with a large overlap with the desired ground state. One approach for preparing such a…

Data representation in quantum state space offers an alternative function space for machine learning tasks. However, benchmarking these algorithms at a practical scale has been limited by ineffective simulation methods. We develop a quantum…

Quantum Physics · Physics 2024-11-15 Mekena Metcalf , Pablo Andrés-Martínez , Nathan Fitzpatrick

Imaginary time evolution is a powerful tool for studying quantum systems. While it is possible to simulate with a classical computer, the time and memory requirements generally scale exponentially with the system size. Conversely, quantum…

Quantum Physics · Physics 2019-09-17 Sam McArdle , Tyson Jones , Suguru Endo , Ying Li , Simon Benjamin , Xiao Yuan

Continuous Matrix Product States (cMPS) are powerful variational ansatz states for ground states of continuous quantum field theories in (1+1) dimension. In this paper we introduce a novel parametrization of the cMPS wave function based on…

Computational Physics · Physics 2017-12-06 Martin Ganahl

Many computationally hard problems can be encoded in quantum Hamiltonians. The solution to these problems is given by the ground states of these Hamiltonians. A state-of-the-art algorithm for finding the ground state of a Hamiltonian is the…

Quantum computers have been widely speculated to offer significant advantages in obtaining the ground state of difficult Hamiltonian in chemistry and physics. In this work, we first propose a Lyapunov control-inspired strategy to accelerate…

Quantum Physics · Physics 2022-12-21 Yu-Cheng Chen , Yu-Qin Chen , Alice Hu , Chang-Yu Hsieh , Shengyu Zhang

Quantum Computing is believed to be the ultimate solution for quantum chemistry problems. Before the advent of large-scale, fully fault-tolerant quantum computers, the variational quantum eigensolver~(VQE) is a promising heuristic quantum…

Quantum Physics · Physics 2023-12-06 Chu Guo , Yi Fan , Zhiqian Xu , Honghui Shang

Numerous methodologies have been proposed to implement imaginary time evolution (ITE) on quantum computers. Among these, variational ITE (VITE) methods for noisy intermediate-scale quantum (NISQ) computers have attracted much attention,…

Quantum Physics · Physics 2025-11-26 Hiroki Kuji , Tetsuro Nikuni , Yuta Shingu

We introduce a functional matrix product state (FMPS) based method for simulating the real-space representation of continuous-variable (CV) quantum computation. This approach efficiently simulates non-Gaussian CV systems by leveraging their…

Quantum Physics · Physics 2026-03-26 Andreas Bock Michelsen , Frederik K. Marqversen , Michael Kastoryano

Subspace diagonalisation methods have appeared recently as promising means to access the ground state and some excited states of molecular Hamiltonians by classically diagonalising small matrices, whose elements can be efficiently obtained…

Quantum Physics · Physics 2024-03-13 Maria-Andreea Filip , David Muñoz Ramo , Nathan Fitzpatrick

Calculating the energy spectrum of a quantum system is an important task, for example to analyse reaction rates in drug discovery and catalysis. There has been significant progress in developing algorithms to calculate the ground state…

Quantum Physics · Physics 2019-06-12 Suguru Endo , Tyson Jones , Sam McArdle , Xiao Yuan , Simon Benjamin

Quantum optimization algorithms offer a promising route to finding the ground states of target Hamiltonians on near-term quantum devices. None the less, it remains necessary to limit the evolution time and circuit depth as much as possible,…

Quantum Physics · Physics 2022-11-01 Chenfeng Cao , Yunlong Yu , Zipeng Wu , Nic Shannon , Bei Zeng , Robert Joynt

Imaginary time evolution is a powerful technique for computing the ground state of quantum Hamiltonians, where the convergence to ground state in asymptotic imaginary time is guaranteed. However, implementing this method on quantum…

Quantum Physics · Physics 2025-06-17 S. Alipour , T. Ojanen

The simulation of quantum systems is a task for which quantum computers are believed to give an exponential speedup as compared to classical ones. While ground states of one-dimensional systems can be efficiently approximated using Matrix…

Quantum Physics · Physics 2009-11-13 Norbert Schuch , Michael M. Wolf , Karl Gerd H. Vollbrecht , J. Ignacio Cirac

Efficient encoding of classical information plays a fundamental role in numerous practical quantum algorithms. However, the preparation of an arbitrary amplitude-encoded state has been proven to be time-consuming, and its deployment on…

Quantum Physics · Physics 2025-08-19 Chao Wang , Pengrui Zhou , Xi-Ning Zhuang , Ziwei Cui , Menghan Dou , Zhao-Yun Chen , Guo-Ping Guo

A generic method to investigate many-body continuous-variable systems is pedagogically presented. It is based on the notion of matrix product states (so-called MPS) and the algorithms thereof. The method is quite versatile and can be…

Strongly Correlated Electrons · Physics 2013-05-29 S. Iblisdir , R. Orus , J. I. Latorre