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We describe a semidefinite relaxation method which finds lower bounds to the ground state energy of a quantum Hamiltonian subject to Hermitian linear constraints along with approximations of ground state expectation values. We show that…

Strongly Correlated Electrons · Physics 2026-05-29 Michael G. Scheer

In this work, we consider a fundamental task in quantum many-body physics - finding and learning ground states of quantum Hamiltonians and their properties. Recent works have studied the task of predicting the ground state expectation value…

Quantum Physics · Physics 2025-01-16 Štěpán Šmíd , Roberto Bondesan

We describe a new polynomial time quantum algorithm that uses the quantum fast fourier transform to find eigenvalues and eigenvectors of a Hamiltonian operator, and that can be applied in cases (commonly found in ab initio physics and…

Quantum Physics · Physics 2009-01-23 Daniel S. Abrams , Seth Lloyd

We derive out a complete series expression of Hamiltonian eigenvalues without any approximation and cut in the general quantum systems based on Wang's formal framework \cite{wang1}. In particular, we then propose a calculating approach of…

Quantum Physics · Physics 2009-11-12 Zhou Li , An Min Wang

We develop a quantum algorithm for estimating the free energy as well as the total Gibbs state of interacting quantum Coulomb gases and molecular systems in dimensions $d \in \{2,3\}$ at finite temperature. These systems lie beyond the…

Quantum Physics · Physics 2026-04-17 Simon Becker , Cambyse Rouzé , Robert Salzmann

We formulate a novel ground state quantum computation approach that requires no unitary evolution of qubits in time: the qubits are fixed in stationary states of the Hamiltonian. This formulation supplies a completely time-independent…

Quantum Physics · Physics 2013-05-29 Ari Mizel , M. W. Mitchell , Marvin L. Cohen

The non-trivial phase structure of the eigenstates of many-body quantum systems severely limits the applicability of quantum Monte Carlo, variational, and machine learning methods. Here, we study real-valued signful ground-state wave…

Disordered Systems and Neural Networks · Physics 2023-10-03 Tom Westerhout , Mikhail I. Katsnelson , Andrey A. Bagrov

The famous, yet unsolved, Fermi-Hubbard model for strongly-correlated electronic systems is a prominent target for quantum computers. However, accurately representing the Fermi-Hubbard ground state for large instances may be beyond the…

The determination of the ground and low-lying excited states is critical in many studies of quantum chemistry and condensed-matter physics. Recent theoretical work proposes a variational quantum eigensolver using ancillary qubits to…

Quantum Physics · Physics 2025-07-22 Huili Zhang , Yibin Guo , Guanglei Xu , Yulong Feng , Jingning Zhang , Hai-feng Yu , S. P. Zhao

Calculating bounds of properties of many-body quantum systems is of paramount importance, since they guide our understanding of emergent quantum phenomena and complement the insights obtained from estimation methods. Recent semidefinite…

Quantum Physics · Physics 2026-01-16 Luke Mortimer , Leonardo Zambrano , Antonio Acín , Donato Farina

Finding the ground state of a quantum many-body system is a fundamental problem in quantum physics. In this work, we give a classical machine learning (ML) algorithm for predicting ground state properties with an inductive bias encoding…

Quantum Physics · Physics 2024-10-18 Laura Lewis , Hsin-Yuan Huang , Viet T. Tran , Sebastian Lehner , Richard Kueng , John Preskill

One of the key applications for the emerging quantum simulators is to emulate the ground state of many-body systems, as it is of great interest in various fields from condensed matter physics to material science. Traditionally, in an analog…

Quantum Physics · Physics 2020-09-18 Chufan Lyu , Victor Montenegro , Abolfazl Bayat

A universal quantum simulator would enable efficient simulation of quantum dynamics by implementing quantum-simulation algorithms on a quantum computer. Specifically the quantum simulator would efficiently generate qubit-string states that…

Quantum Physics · Physics 2013-07-08 Barry C. Sanders

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

We establish a connection between ground states of local quantum Hamiltonians and thermal states of classical spin systems. For any discrete classical statistical mechanical model in any spatial dimension, we find an associated quantum…

Quantum Physics · Physics 2012-03-05 W. Dür , M. Van den Nest

A quantum system will stay near its instantaneous ground state if the Hamiltonian that governs its evolution varies slowly enough. This quantum adiabatic behavior is the basis of a new class of algorithms for quantum computing. We test one…

Quantum Physics · Physics 2009-11-07 Edward Farhi , Jeffrey Goldstone , Sam Gutmann , Joshua Lapan , Andrew Lundgren , Daniel Preda

Obtaining the symmetries of a model is a critical step towards developing an understanding and ultimately analytically or numerically solving the model. However, finding symmetries is generally extremely complicated, often being the result…

We introduce a quantum algorithm to efficiently prepare states with a small energy variance at the target energy. We achieve it by filtering a product state at the given energy with a Lorentzian filter of width $\delta$. Given a local…

Quantum Physics · Physics 2024-07-03 Reinis Irmejs , Mari Carmen Bañuls , J. Ignacio Cirac

In this Letter, we construct the quantum algorithms for the Simon problem and the period-finding problem, which do not require initializing the auxiliary qubits involved in the process of functional evaluation but are as efficient as the…

Quantum Physics · Physics 2007-05-23 Dong Pyo Chi , Jeong San Kim , Soojoon Lee

We present a quantum algorithm for computing the Ramsey numbers whose computational complexity grows super-exponentially with the number of vertices of a graph on a classical computer. The problem is mapped to a decision problem on a…

Quantum Physics · Physics 2016-03-09 Hefeng Wang