The phase diagram of quantum chromodynamics in one dimension on a quantum computer

TL;DR

This paper demonstrates the first quantum simulation of the QCD phase diagram in one dimension at finite density and temperature using a trapped-ion quantum computer, addressing classical computational challenges.

Contribution

It introduces a novel variational method with motional ancillae and charge-singlet measurements to simulate thermal states of SU(2) and SU(3) gauge theories on quantum hardware.

Findings

Successfully prepared thermal states of SU(2) and SU(3) gauge theories

Implemented charge-neutrality constraints on quantum hardware

Paved the way for future quantum simulations of QCD phenomena

Abstract

The quantum chromodynamics (QCD) phase diagram, which reveals the state of strongly interacting matter at different temperatures and densities, is key to answering open questions in physics, ranging from the behavior of particles in neutron stars to the conditions of the early universe. However, classical simulations of QCD face significant computational barriers, such as the sign problem at finite matter densities. Quantum computing offers a promising solution to overcome these challenges. Here, we take an important step toward exploring the QCD phase diagram with quantum devices by preparing thermal states in one-dimensional non-Abelian gauge theories. We experimentally simulate the thermal states of SU(2) and SU(3) gauge theories at finite densities on a trapped-ion quantum computer using a variational method. This is achieved by introducing two features: Firstly, we add motional ancillae to the existing qubit register to efficiently prepare thermal probability distributions. Secondly, we introduce charge-singlet measurements to enforce color-neutrality constraints. This work marks the first lattice gauge theory quantum simulation of QCD at finite density and temperature for two and three colors, laying the foundation to explore QCD phenomena on quantum platforms.