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Solutions to many-body problem instances often involve an intractable number of degrees of freedom and admit no known approximations in general form. In practice, representing quantum-mechanical states of a given Hamiltonian using available…

Quantum Physics · Physics 2020-11-10 Andrey Kardashin , Alexey Uvarov , Dmitry Yudin , Jacob Biamonte

We present a framework for simulating the open dynamics of spin-boson systems by combining variational non-Gaussian states with a quantum trajectories approach. We apply this method to a generic spin-boson Hamiltonian that has both…

We study the non-equilibrium steady state arising from the interplay between coherent and dissipative dynamics in strongly interacting Rydberg gases using a recently introduced variational method [H. Weimer, Phys. Rev. Lett. 114, 040402…

Quantum Gases · Physics 2015-02-20 Hendrik Weimer

We present a class of optimum ground states for spin-3/2 models on the Cayley tree with coordination number 3. The interaction is restricted to nearest neighbours and contains 5 continuous parameters. For all values of these parameters the…

Statistical Mechanics · Physics 2009-10-31 H. Niggemann , J. Zittartz

For predictive modeling relying on Bayesian inversion, fully independent, or ``mean-field'', Gaussian distributions are often used as approximate probability density functions in variational inference since the number of variational…

Methodology · Statistics 2023-07-14 Wyatt Bridgman , Reese Jones , Mohammad Khalil

The energy levels of the ground states of the three-particle and four-particle bound states of leptons in quantum electrodynamics are calculated. For the calculation, the variational method with Gaussian basis functions is used. The…

High Energy Physics - Phenomenology · Physics 2026-03-09 A. V. Eskin , A. P. Martynenko , F. A. Martynenko , D. K. Pometko

For a wide class of Hamiltonians, a novel method to obtain lower and upper bounds for the lowest energy is presented. Unlike perturbative or variational techniques, this method does not involve the computation of any integral (a…

Quantum Physics · Physics 2009-11-10 Amaury Mouchet

We investigate the existence and the properties of fully separable (fully factorized) ground states in quantum spin systems. Exploiting techniques of quantum information and entanglement theory we extend a recently introduced method and…

Statistical Mechanics · Physics 2009-07-01 S. M. Giampaolo , G. Adesso , F. Illuminati

We give a functional integral representation of the semigroup generated by the spin-boson Hamiltonian by making use of a Poisson point process and a Euclidean field. We present a method of constructing Gibbs path measures indexed by the…

Mathematical Physics · Physics 2014-04-08 Masao Hirokawa , Fumio Hiroshima , Jozsef Lorinczi

We benchmark the accuracy of a variational quantum eigensolver based on a finite-depth quantum circuit encoding ground state of local Hamiltonians. We show that in gapped phases, the accuracy improves exponentially with the depth of the…

The global coupling of few-level quantum systems ("spins") to a discrete set of bosonic modes is a key ingredient for many applications in quantum science, including large-scale entanglement generation, quantum simulation of the dynamics of…

Quantum Gases · Physics 2016-12-07 Michael L. Wall , Arghavan Safavi-Naini , Ana Maria Rey

Reliable preparation of many-body ground states is an essential task in quantum computing, with applications spanning areas from chemistry and materials modeling to quantum optimization and benchmarking. A variety of approaches have been…

Quantum Physics · Physics 2026-02-09 Ricard Puig , Berta Casas , Alba Cervera-Lierta , Zoë Holmes , Adrián Pérez-Salinas

We present a new variational method for investigating the ground state and out of equilibrium dynamics of quantum many-body bosonic and fermionic systems. Our approach is based on constructing variational wavefunctions which extend Gaussian…

Quantum Physics · Physics 2018-03-14 Tao Shi , Eugene Demler , J. Ignacio Cirac

A fundamental challenge in quantum physics is determining the ground-state properties of many-body systems. Whereas standard approaches, such as variational calculations, consist of writing down a wave function ansatz and minimizing over…

Quantum Physics · Physics 2026-04-03 Jie Wang , David Jansen , Irénée Frerot , Marc-Olivier Renou , Victor Magron , Antonio Acín

A variational model for the infra-red spectrum of VO is presented which aims to accurately predict the hyperfine structure within the VO $\mathrm{X}\,^4\Sigma^-$ electronic ground state. To give the correct electron spin splitting of the…

Chemical Physics · Physics 2022-10-25 Qianwei Qu , Sergei N. Yurchenko , Jonathan Tennyson

We propose applying the adiabatic algorithm to prepare high-energy eigenstates of integrable models on a quantum computer. We first review the standard adiabatic algorithm to prepare ground states in each magnetization sector of the…

Quantum Physics · Physics 2026-03-18 Maximilian Lutz , Lorenzo Piroli , Georgios Styliaris , J. Ignacio Cirac

We study integrable models for electrons in metals when the single particle spectrum is discrete. The electron-electron interactions are BCS-like pairing, Coulomb repulsion, and spin exchange coupling. These couplings are, in general,…

Superconductivity · Physics 2011-07-19 Luigi Amico , Antonio Di Lorenzo , Andreas Osterloh

In the presented article we present an algorithm for the computation of ground state spin configurations for the 2d random bond Ising model on planar triangular lattice graphs. Therefore, it is explained how the respective ground state…

Disordered Systems and Neural Networks · Physics 2015-05-19 O. Melchert , A. K. Hartmann

Determining properties of ground states of spin Hamiltonians remains a topic of central relevance connecting disciplines of mathematical, theoretical and applied physics. In the last few decades, ground state properties of physical systems…

Quantum Physics · Physics 2021-12-28 Jacob Biamonte

Variational phase-field models of brittle fracture are powerful tools for studying Griffith-type crack propagation in complex scenarios. However, as approximations of Griffith's theory-which does not incorporate a strength criterion-these…

Applied Physics · Physics 2026-01-06 Francesco Vicentini , Jonas Heinzmann , Pietro Carrara , Laura De Lorenzis