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Related papers: Quantum Algorithm for Preparing Thermal Gibbs Stat…

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We introduce a method that ensures efficient computation of one-dimensional quantum systems with long-range interactions across all temperatures. Our algorithm operates within a quasi-polynomial runtime for inverse temperatures up to…

Quantum Physics · Physics 2025-05-19 Rakesh Achutha , Donghoon Kim , Yusuke Kimura , Tomotaka Kuwahara

{Many-body quantum states at thermal equilibrium are ubiquitous in nature. Investigating their dynamical properties is a formidable task due to the complexity of the Hilbert space they live in. Quantum computers may have the potential to…

Quantum Physics · Physics 2024-07-25 Mirko Consiglio , Tony J. G. Apollaro

Estimating thermal expectation values of observables is a fundamental task in quantum physics, quantum chemistry, and materials science. While recent quantum algorithms have enabled efficient quantum preparation of thermal states,…

Quantum Physics · Physics 2026-02-16 Jiaqing Jiang , Jiaqi Leng , Lin Lin

In the current Noisy Intermediate-Scale Quantum era, noise is widely regarded as the primary obstacle to achieving fault-tolerant quantum computation. However, certain stages of the quantum computing pipeline can, in fact, benefit from this…

Quantum Physics · Physics 2025-12-18 Sameer Dambal , Yu Zhang , Eric R Bittner , Pavan Hosur

The preparation of thermal equilibrium states is important for the simulation of condensed-matter and cosmology systems using a quantum computer. We present a method to prepare such mixed states with unitary operators, and demonstrate this…

We introduce a classical algorithm to approximate the free energy of local, translation-invariant, one-dimensional quantum systems in the thermodynamic limit of infinite chain size. While the ground state problem (i.e., the free energy at…

Quantum Physics · Physics 2024-07-04 Hamza Fawzi , Omar Fawzi , Samuel O. Scalet

Calculations at finite temperatures are fundamental in different scientific fields, from nuclear physics to condensed matter. Evolution in imaginary time is a prominent classical technique for preparing thermal states of quantum systems. We…

Quantum Physics · Physics 2023-06-30 Francesco Turro

We show that thermal states of local Hamiltonians are separable above a constant temperature. Specifically, for a local Hamiltonian $H$ on a graph with degree $\mathfrak{d}$, its Gibbs state at inverse temperature $\beta$, denoted by $\rho…

Quantum Physics · Physics 2025-02-25 Ainesh Bakshi , Allen Liu , Ankur Moitra , Ewin Tang

We introduce the CaRBM algorithm for fixed-depth thermal state preparation. Our algorithm is based on thermal state purification and uses the Restricted Boltzmann Machine (RBM) block-encoding scheme to implement the imaginary-time…

Quantum Physics · Physics 2026-03-24 Omar Alsheikh , A. F. Kemper , Ermal Rrapaj , Evan J. Rule , Goksu C. Toga

We study the problem of learning a Hamiltonian $H$ to precision $\varepsilon$, supposing we are given copies of its Gibbs state $\rho=\exp(-\beta H)/\operatorname{Tr}(\exp(-\beta H))$ at a known inverse temperature $\beta$. Anshu,…

Quantum Physics · Physics 2025-10-14 Jeongwan Haah , Robin Kothari , Ewin Tang

We propose a polynomial-time algorithm for preparing the Gibbs state of the two-dimensional toric code Hamiltonian at any temperature, starting from any initial condition, significantly improving upon prior estimates that suggested…

Quantum Physics · Physics 2025-05-02 Zhiyan Ding , Zeph Landau , Bowen Li , Lin Lin , Ruizhe Zhang

We investigate the multiparameter quantum estimation and quantum thermodynamics properties of a gravitational cat state (gravcat) system composed of two interacting massive particles confined in double-well potentials. The system is…

Quantum Physics · Physics 2026-03-20 Omar Bachain , Mohamed Amazioug , Rachid Ahl Laamara

Semidefinite programs (SDPs) are a particular class of convex optimization problems with applications in combinatorial optimization, operational research, and quantum information science. Seminal work by Brand\~{a}o and Svore shows that a…

Quantum Physics · Physics 2023-10-13 Oscar Watts , Yuta Kikuchi , Luuk Coopmans

We simulate the critical behavior of the Ising model utilizing a thermal state prepared using quantum computing techniques. The preparation of the thermal state is based on the variational quantum imaginary time evolution (QITE) algorithm.…

Quantum Physics · Physics 2023-09-07 Xiaoyang Wang , Xu Feng , Tobias Hartung , Karl Jansen , Paolo Stornati

We study the problem of learning a local quantum Hamiltonian $H$ given copies of its Gibbs state $\rho = e^{-\beta H}/\textrm{tr}(e^{-\beta H})$ at a known inverse temperature $\beta>0$. Anshu, Arunachalam, Kuwahara, and Soleimanifar…

Quantum Physics · Physics 2026-05-11 Ainesh Bakshi , Allen Liu , Ankur Moitra , Ewin Tang

Quantum dynamics can be analyzed via the structure of energy eigenstates. However, in the many-body setting, preparing eigenstates associated with finite temperatures requires time scaling exponentially with system size. In this work we…

Quantum Physics · Physics 2024-07-11 Samuel J. Garratt , Soonwon Choi

The preparation of quantum Gibbs state is an essential part of quantum computation and has wide-ranging applications in various areas, including quantum simulation, quantum optimization, and quantum machine learning. In this paper, we…

Quantum Physics · Physics 2021-11-23 Youle Wang , Guangxi Li , Xin Wang

Many physical phenomena, including thermalization in open quantum systems and quantum Gibbs sampling, are modeled by Lindbladians approximating a system weakly coupled to a bath. Understanding the convergence speed of these Lindbladians to…

Quantum Gibbs state sampling algorithms generally suffer from either scaling exponentially with system size or requiring specific knowledge of spectral properties \textit{a priori}. Also, these algorithms require a large overhead of bath or…

Quantum Physics · Physics 2020-09-02 Jeffrey Cohn , Khadijeh Sona Najafi , Forest Yang , Barbara Jones , James K. Freericks

Efficient simulation of a quantum system generally relies on structural properties of the quantum state. Motivated by the recent results by Bakshi et al. on the sudden death of entanglement in high-temperature Gibbs states of quantum spin…

Quantum Physics · Physics 2026-01-21 Akshar Ramkumar , Yiyi Cai , Yu Tong , Jiaqing Jiang