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While quantum simulation is one of the most promising applications of modern quantum devices, accessible simulation times are fundamentally limited by finite coherence times due to omnipresent noise. Based on the ideas of relational…

Quantum Physics · Physics 2025-09-03 Sebastian Gemsheim , Felix Fritzsch

We introduce a complete description of a multi-mode bosonic quantum state in the coherent-state basis (which in this work is denoted as "$K$" function ), which---up to a phase---is the square root of the well-known Husimi "$Q$"…

Quantum Physics · Physics 2019-05-16 Christos Gagatsos , Saikat Guha

Imaginary time evolution is a powerful tool applied in quantum physics, while existing classical algorithms for simulating imaginary time evolution suffer high computational complexity as the quantum systems become larger and more complex.…

Quantum Physics · Physics 2022-10-12 Hao-Nan Xie , Shi-Jie Wei , Fan Yang , Zheng-An Wang , Chi-Tong Chen , Heng Fan , Gui-Lu Long

We compare recently proposed methods to compute the electronic state energies of the water molecule on a quantum computer. The methods include the phase estimation algorithm based on Trotter decomposition, the phase estimation algorithm…

Quantum Physics · Physics 2019-07-24 Teng Bian , Daniel Murphy , Rongxin Xia , Ammar Daskin , Sabre Kais

A central challenge in quantum computing is to identify more computational problems for which utilization of quantum resources can offer significant speedup. Here, we propose a hybrid quantum-classical scheme to tackle the quantum optimal…

Quantum Physics · Physics 2017-04-19 Jun Li , Xiaodong Yang , Xinhua Peng , Chang-Pu Sun

We delve into the use of photonic quantum computing to simulate quantum mechanics and extend its application towards quantum field theory. We develop and prove a method that leverages this form of Continuous-Variable Quantum Computing…

Quantum Physics · Physics 2024-07-11 Steven Abel , Michael Spannowsky , Simon Williams

We present a hybrid classical/quantum algorithm for efficiently solving the eigenvalue problem of many-particle Hamiltonians on quantum computers with limited resources by splitting the workload between classical and quantum processors.…

Quantum Physics · Physics 2022-03-01 John P. T. Stenger , Daniel Gunlycke , C. Stephen Hellberg

An iterative version of the qubit coupled cluster (QCC) method [I.G. Ryabinkin et al., J. Chem. Theory Comput. 14, 6317 (2019)] is proposed. The new method seeks to find ground electronic energies of molecules on noisy intermediate-scale…

Quantum Physics · Physics 2019-10-28 Ilya G. Ryabinkin , Robert A. Lang , Scott N. Genin , Artur F. Izmaylov

We introduce a hybrid classical-quantum algorithm for simulating a Hamiltonian of the form $H= \sum_{i=1}^K H_i = \sum_{i=1}^K H_{i_1} \otimes H_{i_2} \otimes \cdots \otimes H_{i_M}$. Given that the entries of all $\{ H_{i_1}, H_{i_2} ,…

Quantum Physics · Physics 2026-04-08 Nhat A. Nghiem , Tzu-Chieh Wei

The key approaches for machine learning, especially learning in unknown probabilistic environments are new representations and computation mechanisms. In this paper, a novel quantum reinforcement learning (QRL) method is proposed by…

Quantum Physics · Physics 2008-10-22 Daoyi Dong , Chunlin Chen , Hanxiong Li , Tzyh-Jong Tarn

Quantum circuit partitioning (QCP) is a hybrid quantum-classical approach that aims to simulate large quantum systems on smaller quantum computers. A quantum computation is divided into smaller subsystems and results of measurements on…

Quantum Physics · Physics 2024-09-20 Stian Bilek

To efficiently implement many-qubit gates for use in quantum simulations on quantum computers we develop and present methods reexpressing exp[-i (H_1 + H_2 + ...) \Delta t] as a product of factors exp[-i H_1 \Delta t], exp[-i H_2 \Delta t],…

Quantum Physics · Physics 2009-10-31 A. T. Sornborger , E. D. Stewart

The quantum circuit model is the de-facto way of designing quantum algorithms. Yet any level of abstraction away from the underlying hardware incurs overhead. In the era of near-term, noisy, intermediate-scale quantum (NISQ) hardware with…

Quantum Physics · Physics 2021-08-27 Laura Clinton , Johannes Bausch , Toby Cubitt

Quantum chemistry has been viewed as one of the potential early applications of quantum computing. Two techniques have been proposed for electronic structure calculations: (i) the variational quantum eigensolver and (ii) the…

Quantum Physics · Physics 2021-04-19 Christina Daniel , Diksha Dhawan , Dominika Zgid , James K. Freericks

Hybrid quantum-classical (HQC) algorithms make it possible to use near-term quantum devices supported by classical computational resources by useful control schemes. In this paper, we develop an HQC algorithm using an efficient variational…

Quantum Physics · Physics 2020-08-13 Mahmoud Mahdian , H. Davoodi Yeganeh

Many claims of computational advantages have been made for quantum computing over classical, but they have not been demonstrated for practical problems. Here, we present algorithms for solving time-dependent PDEs, with particular reference…

Quantum Physics · Physics 2025-06-17 Sachin S. Bharadwaj , Katepalli R. Sreenivasan

The calculation of excited state energies of electronic structure Hamiltonians has many important applications, such as the calculation of optical spectra and reaction rates. While low-depth quantum algorithms, such as the variational…

Quantum Physics · Physics 2019-07-03 Oscar Higgott , Daochen Wang , Stephen Brierley

While the preparation of a general quantum state is challenging, realistic problem instances, such as those encountered in quantum chemistry and quantum machine learning-typically exhibit hierarchical amplitude structures, consisting of a…

Quantum Physics · Physics 2026-01-15 Yue Wang , Xiao-Ming Zhang , Xiao Yuan , Qi Zhao

Quantum state tomography is an essential tool for the characterization and verification of quantum states. However, as it cannot be directly applied to systems with more than a few qubits, efficient tomography of larger states on mid-sized…

Quantum Physics · Physics 2023-02-01 Yotam Y. Lifshitz , Eyal Bairey , Eli Arbel , Gadi Aleksandrowicz , Haggai Landa , Itai Arad

We present a quantum algorithm for the dynamical simulation of time-dependent Hamiltonians. Our method involves expanding the interaction-picture Hamiltonian as a sum of generalized permutations, which leads to an integral-free Dyson series…

Quantum Physics · Physics 2021-09-15 Yi-Hsiang Chen , Amir Kalev , Itay Hen