Variational thermal quantum simulation of the lattice Schwinger model

TL;DR

This paper introduces a variational quantum simulation method for the lattice Schwinger model to study confinement phenomena at finite temperature and density, providing insights into the QCD phase diagram using near-term quantum computers.

Contribution

It proposes a novel variational approach to simulate confinement and deconfinement in the lattice Schwinger model without requiring entropy measurements, advancing quantum simulation of nuclear matter.

Findings

String tension decreases with increasing temperature and chemical potential.

Simulation results mimic the QCD phase diagram.

Method demonstrates potential for near-term quantum computers.

Abstract

Confinement of quarks due to the strong interaction and the deconfinement at high temperatures and high densities are a basic paradigm for understanding the nuclear matter. Their simulation, however, is very challenging for classical computers due to the sign problem of solving equilibrium states of finite-temperature quantum chromodynamical systems at finite density. In this paper, we propose a variational approach, using the lattice Schwinger model, to simulate the confinement or deconfinement by investigating the string tension. We adopt an ansatz that the string tension can be evaluated without referring to quantum protocols for measuring the entropy in the free energy. Results of numeral simulation show that the string tension decreases both along the increasing of the temperature and the chemical potential, which can be an analog of the phase diagram of QCD. Our work paves a way for exploiting near-term quantum computers for investigating the phase diagram of finite-temperature and finite density for nuclear matters.