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Simulating the unitary dynamics of a quantum system is a fundamental problem of quantum mechanics, in which quantum computers are believed to have significant advantage over their classical counterparts. One prominent such instance is the…

Quantum Physics · Physics 2024-09-04 John M. Martyn , Yuan Liu , Zachary E. Chin , Isaac L. Chuang

We present a systematic study of quantum system compression for the evolution of generic many-body problems. The necessary numerical simulations of such systems are seriously hindered by the exponential growth of the Hilbert space dimension…

Quantum Physics · Physics 2021-01-20 Robert L. Kosut , Tak-San Ho , Herschel Rabitz

Based on recently introduced efficient quantum state tomography schemes, we propose a scalable method for the tomography of unitary processes and the reconstruction of one-dimensional local Hamiltonians. As opposed to the exponential…

Quantum Physics · Physics 2015-04-30 M. Holzäpfel , T. Baumgratz , M. Cramer , M. B. Plenio

Photons are elementary particles of light in quantum mechanics, whose dynamics can be difficult to gain detailed insights, especially in complex systems. Simulation is a promising tool to resolve this issue, but it must address the curse of…

Quantum Physics · Physics 2024-02-21 Junpei Oba , Seiji Kajita , Akihito Soeda

Simulating large-scale coupled-oscillator systems presents substantial computational challenges for classical algorithms, particularly when pursuing first-principles analyses in the thermodynamic limit. Motivated by the quantum algorithm…

Transport phenomena play a key role in a variety of application domains, and efficient simulation of these dynamics remains an outstanding challenge. While quantum computers offer potential for significant speedups, existing algorithms…

Quantum Physics · Physics 2026-02-04 Joseph Li , Gengzhi Yang , Jiaqi Leng , Xiaodi Wu

This paper proposes Hamiltonian Learning, a novel unified framework for learning with neural networks "over time", i.e., from a possibly infinite stream of data, in an online manner, without having access to future information. Existing…

Machine Learning · Computer Science 2024-09-19 Stefano Melacci , Alessandro Betti , Michele Casoni , Tommaso Guidi , Matteo Tiezzi , Marco Gori

Quantum signal processing combined with quantum eigenvalue transformation has recently emerged as a unifying framework for several quantum algorithms. In its standard form, it consists of two separate routines: block encoding, which encodes…

Quantum Physics · Physics 2024-10-25 Martina Nibbi , Christian B. Mendl

We present a quantum computational framework using Hamiltonian Truncation (HT) for simulating real-time scattering processes in $(1+1)$-dimensional scalar $\phi^4$ theory. Unlike traditional lattice discretisation methods, HT approximates…

Quantum Physics · Physics 2025-05-08 James Ingoldby , Michael Spannowsky , Timur Sypchenko , Simon Williams , Matthew Wingate

We show that quantum circuit complexity for the unitary time evolution operator of any time-independent Hamiltonian is bounded by linear growth at early times, independent of any choices of the fundamental gates or cost metric. Deviations…

High Energy Physics - Theory · Physics 2024-10-15 S. Shajidul Haque , Ghadir Jafari , Bret Underwood

Digital-analog quantum computation aims to reduce the currently infeasible resource requirements needed for near-term quantum information processing by replacing sequences of one- and two-qubit gates with a unitary transformation generated…

Nonequilibrium time evolution of large quantum systems is a strong candidate for quantum advantage. Variational quantum algorithms have been put forward for this task, but their quantum optimization routines suffer from trainability and…

Quantum Physics · Physics 2024-07-12 Refik Mansuroglu , Felix Fischer , Michael J. Hartmann

Computational spectral imaging is drawing increasing attention owing to the snapshot advantage, and amplitude, phase, and wavelength encoding systems are three types of representative implementations. Fairly comparing and understanding the…

Image and Video Processing · Electrical Eng. & Systems 2023-12-22 Xinyuan Liu , Lizhi Wang , Lingen Li , Chang Chen , Xue Hu , Fenglong Song , Youliang Yan

We introduce a family of identities that express general linear non-unitary evolution operators as a linear combination of unitary evolution operators, each solving a Hamiltonian simulation problem. This formulation can exponentially…

Quantum Physics · Physics 2025-12-16 Dong An , Andrew M. Childs , Lin Lin

Determining the Hamiltonian of a quantum system is essential for understanding its dynamics and validating its behavior. Hamiltonian learning provides a data-driven approach to reconstruct the generator of the dynamics from measurements on…

We describe an improved version of the quantum simulation method based on the implementation of a truncated Taylor series of the evolution operator. The idea is to add an extra step to the previously known algorithm which implements an…

Quantum Physics · Physics 2017-06-05 Leonardo Novo , Dominic W. Berry

X-ray absorption spectroscopy (XAS) is a leading technique for understanding structural changes in advanced battery materials such as lithium-excess cathodes. However, extracting critical information like oxidation states from the…

One of the crucial generic techniques for quantum computation is amplitude encoding. Although several approaches have been proposed, each of them often requires exponential classical-computational cost or an oracle whose explicit…

Quantum Physics · Physics 2024-12-06 Taichi Kosugi , Shunsuke Daimon , Hirofumi Nishi , Shinji Tsuneyuki , Yu-ichiro Matsushita

Recent work has characterised rigorously what it means for one quantum system to simulate another, and demonstrated the existence of universal Hamiltonians -- simple spin lattice Hamiltonians that can replicate the entire physics of any…

Quantum Physics · Physics 2021-10-26 Tamara Kohler , Stephen Piddock , Johannes Bausch , Toby Cubitt

Hamiltonian simulation is a key workload in quantum computing, enabling the study of complex quantum systems and serving as a critical tool for classical verification of quantum devices. However, it is computationally challenging because…

Hardware Architecture · Computer Science 2025-10-31 Yuchao Su , Srikar Chundury , Jiajia Li , Frank Mueller