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We present a general protocol for estimating $M$ observables from only $\mathcal{O}(\log (M)/\varepsilon^2)$ copies of a Gibbs state whose Hamiltonian is accessible. The protocol uses single-copy, nonadaptive measurements and uses a total…

Quantum Physics · Physics 2026-03-18 Chi-Fang Chen , András Gilyén

This work introduces an approach rooted in quantum thermodynamics to enhance sampling efficiency in quantum machine learning (QML). We propose conceptualizing quantum supervised learning as a thermodynamic cooling process. Building on this…

Quantum Physics · Physics 2025-01-07 Nayeli A. Rodríguez-Briones , Daniel K. Park

We develop a framework for learning properties of quantum states beyond the assumption of independent and identically distributed (i.i.d.) input states. We prove that, given any learning problem (under reasonable assumptions), an algorithm…

Quantum Physics · Physics 2024-11-15 Omar Fawzi , Richard Kueng , Damian Markham , Aadil Oufkir

The characterization of Hamiltonians and other components of open quantum dynamical systems plays a crucial role in quantum computing and other applications. Scientific machine learning techniques have been applied to this problem in a…

Quantum Physics · Physics 2026-04-07 Peter Sentz , Stanley Nicholson , Yujin Cho , Sohail Reddy , Brendan Keith , Stefanie Günther

Quantum Boltzmann machines (QBMs) are machine-learning models for both classical and quantum data. We give an operational definition of QBM learning in terms of the difference in expectation values between the model and target, taking into…

Quantum Physics · Physics 2025-02-13 Luuk Coopmans , Marcello Benedetti

We present a cooling algorithm for ground state preparation of fermionic Hamiltonians. Our algorithm makes use of the Hamiltonian simulation of the considered system coupled to an ancillary fridge, which is regularly reset to its known…

Quantum Physics · Physics 2025-02-19 Lucas Marti , Refik Mansuroglu , Michael J. Hartmann

Preparation of Gibbs distributions is an important task for quantum computation. It is a necessary first step in some types of quantum simulations and further is essential for quantum algorithms such as quantum Boltzmann training. Despite…

Quantum Physics · Physics 2020-02-04 Anirban N. Chowdhury , Guang Hao Low , Nathan Wiebe

We show that it is possible to uniquely reconstruct a generic many-body local Hamiltonian from a single pair of initial and final states related by time evolution with the Hamiltonian. We then propose a practical version of the protocol…

Quantum Physics · Physics 2020-04-28 Zhi Li , Liujun Zou , Timothy H. Hsieh

We introduce novel algorithms for the quantum simulation of molecular systems which are asymptotically more efficient than those based on the Trotter-Suzuki decomposition. We present the first application of a recently developed technique…

We construct a simple translationally invariant, nearest-neighbor Hamiltonian on a chain of 10-dimensional qudits that makes it possible to realize universal quantum computing without any external control during the computational process.…

Quantum Physics · Physics 2009-11-13 Daniel Nagaj , Pawel Wocjan

Predicting observables in equilibrium states is a central yet notoriously hard question in quantum many-body systems. In the physically relevant thermodynamic limit, certain mathematical formulations of this task have even been shown to…

Quantum Physics · Physics 2025-08-15 Hamza Fawzi , Omar Fawzi , Samuel O. Scalet

Quantum computing can be used to speed up the simulation time (more precisely, the number of queries of the algorithm) for physical systems; one such promising approach is the Hamiltonian simulation (HS) algorithm. Recently, it was proven…

Quantum Physics · Physics 2023-10-25 Kiichiro Toyoizumi , Naoki Yamamoto , Kazuo Hoshino

The problem of simulating the thermal behavior of quantum systems remains a central open challenge in quantum computing. Unlike well-established quantum algorithms for unitary dynamics, \emph{provably efficient} algorithms for preparing…

Quantum Physics · Physics 2026-05-14 Dominik Hahn , Ryan Sweke , Abhinav Deshpande , Oles Shtanko

We propose a quantum algorithm to obtain the lowest eigenstate of any Hamiltonian simulated by a quantum computer. The proposed algorithm begins with an arbitrary initial state of the simulated system. A finite series of transforms is…

Quantum Physics · Physics 2015-01-08 Jeongho Bang , Seung-Woo Lee , Chang-Woo Lee , Hyunseok Jeong

Finding the ground state of a Hamiltonian system is of great significance in many-body quantum physics and quantum chemistry. We propose an improved iterative quantum algorithm to prepare the ground state of a Hamiltonian. The crucial point…

Quantum Physics · Physics 2022-10-25 Jin-Min Liang , Qiao-Qiao Lv , Shu-Qian Shen , Ming Li , Zhi-Xi Wang , Shao-Ming Fei

Simulating the time-evolution of quantum mechanical systems is BQP-hard and expected to be one of the foremost applications of quantum computers. We consider classical algorithms for the approximation of Hamiltonian dynamics using…

We consider the task of approximating the ground state energy of two-local quantum Hamiltonians on bounded-degree graphs. Most existing algorithms optimize the energy over the set of product states. Here we describe a family of shallow…

Quantum Physics · Physics 2022-01-05 Anurag Anshu , David Gosset , Karen J. Morenz Korol , Mehdi Soleimanifar

Efficient sampling from ensembles of Hamiltonian cycles is critical for predicting the thermodynamic properties of compact polymers, with applications including modeling protein and RNA folding and designing soft materials. Although…

Quantum Physics · Physics 2026-03-16 Davide Rattacaso , Daniel Jaschke , Antonio Trovato , Ilaria Siloi , Simone Montangero

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

We investigate the problem of determining the Hamiltonian of a locally interacting open-quantum system. To do so, we construct model estimators based on inverting a set of stationary, or dynamical, Heisenberg-Langevin equations of motion…

Quantum Physics · Physics 2020-08-19 Eugene F. Dumitrescu , Pavel Lougovski