Variational thermal quantum simulation of the lattice Schwinger model

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. Through numerical simulations on the classical computer, we demonstrate the potential of exploiting near-term quantum computers for investigating the phase diagram of finite-temperature and finite-density nuclear matters.

Automated summary

This paper proposes a variational approach using lattice Schwinger model to simulate the confinement or deconfinement, and shows the changes in string tension with temperature and chemical potential through numerical simulations. The potential of using quantum computers to investigate the phase diagram of finite-temperature and finite-density nuclear matters is demonstrated through simulations on classical computers.