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We present quantum algorithms for solving two problems regarding stochastic processes. The first algorithm prepares the thermal Gibbs state of a quantum system and runs in time almost linear in $\sqrt{N \beta/{\cal Z}}$ and polynomial in…

Quantum Physics · Physics 2017-01-11 Anirban Narayan Chowdhury , Rolando D. Somma

This paper discusses a classical simulation to compute the partition function (or free energy) of generic one-dimensional quantum many-body systems. Many numerical methods have previously been developed to approximately solve…

Quantum Physics · Physics 2018-07-24 Tomotaka Kuwahara , Keiji Saito

Temperature determines the relative probability of observing a physical system in an energy state when that system is energetically in equilibrium with its environment. In this paper, we present a theory for engineering the temperature of a…

Quantum Physics · Physics 2016-11-09 Alireza Shabani , Hartmut Neven

The preparation of an equilibrium thermal state of a quantum many-body system on noisy intermediate-scale quantum (NISQ) devices is an important task in order to extend the range of applications of quantum computation. Faithful Gibbs state…

Calculating the properties of Gibbs states is an important task in Quantum Chemistry and Quantum Machine Learning. Previous work has proposed a quantum algorithm which predicts Gibbs state expectation values for $M$ observables from only…

Quantum Physics · Physics 2024-09-10 Arnav Sharma , Kevin Obenland

It is proposed that the ability for a quantum circuit to thermalize under time evolution is a valid way to compute linear algebra problems. The algorithm makes use of the eigenstate thermalization hypothesis and full ergodicity in quantum…

Quantum Physics · Physics 2026-05-27 Thomas E. Baker

Sampling from Gibbs states -- states corresponding to system in thermal equilibrium -- has recently been shown to be a task for which quantum computers are expected to achieve super-polynomial speed-up compared to classical computers,…

Quantum Physics · Physics 2026-01-28 Joel Rajakumar , James D. Watson

We consider the problem of preparing thermal equilibrium states at finite temperature on quantum computers. Assuming thermalization, we show that states that are locally at thermal equilibrium can be prepared by evolving adiabatically an…

Quantum Physics · Physics 2026-04-21 Etienne Granet , Henrik Dreyer

Optimizing open quantum system evolution is an important step on the way to achieving quantum computing and quantum thermodynamic tasks. In this article, we approach optimisation via variational principles and derive an open quantum system…

Quantum Physics · Physics 2018-10-17 Nishchay Suri , Felix C. Binder , Bhaskaran Muralidharan , Sai Vinjanampathy

In this paper we develop a quantum algorithm to realize finite temperature simulation on a quantum computer. As quantum computers use real-time evolution we did not use the imaginary time methods popular on classical algorithms. Instead, we…

Quantum Physics · Physics 2019-11-11 Raffaele Miceli , Michael McGuigan

Preparing Gibbs states, which describe systems in equilibrium at finite temperature, is of great importance, particularly at low temperatures. In this work, we propose a new method -- TEPID-ADAPT -- that prepares the thermal Gibbs state of…

Calculating the physical properties of quantum thermal states is a difficult problem for classical computers, rendering it intractable for most quantum many-body systems. A quantum computer, by contrast, would make many of these…

Strongly Correlated Electrons · Physics 2019-11-19 John Martyn , Brian Swingle

The computational complexity of simulating quantum many-body systems generally scales exponentially with the number of particles. This enormous computational cost prohibits first principles simulations of many important problems throughout…

Quantum Physics · Physics 2023-05-31 Chao Yin , Andrew Lucas

Providing the microscopic behavior of a thermalization process has always been an intriguing issue. There are several models of thermalization, which often requires interaction of the system under consideration with the microscopic…

Quantum Physics · Physics 2019-07-24 Prathik J Cherian , Sagnik Chakraborty , Sibasish Ghosh

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

A measurement-based quantum computer could consist of a local-gapped Hamiltonian system, whose thermal states --at sufficiently low temperature-- are universal resources for the computation. Initialization of the computer would correspond…

Quantum Physics · Physics 2015-06-18 G. H. Aguilar , T. Kolb , D. Cavalcanti , L. Aolita , R. Chaves , S. P. Walborn , P. H. Souto Ribeiro

Quantum cooling, a deterministic process that drives any state to the lowest eigenstate, has been widely used from studying ground state properties of chemistry and condensed matter quantum physics, to general optimization problems.…

Quantum Physics · Physics 2022-06-06 Pei Zeng , Jinzhao Sun , Xiao Yuan

Many quantum technologies, including quantum computers, quantum heat engines, and quantum sensors, rely on operating conditions in the subkelvin regime. It is therefore desirable to develop practical tools and methods for the precise…

Mesoscale and Nanoscale Physics · Physics 2025-03-28 Riya Baruah , Pedro Portugal , Joachim Wabnig , Christian Flindt

Thermalization is the process through which a physical system evolves toward a state of thermal equilibrium. Determining whether or not a physical system will thermalize from an initial state has been a key question in condensed matter…

Quantum Physics · Physics 2026-01-05 Dhruv Devulapalli , T. C. Mooney , James D. Watson

Learning the Hamiltonian underlying a quantum many-body system in thermal equilibrium is a fundamental task in quantum learning theory and experimental sciences. To learn the Gibbs state of local Hamiltonians at any inverse temperature…

Quantum Physics · Physics 2025-04-04 Chi-Fang Chen , Anurag Anshu , Quynh T. Nguyen