Quantum Computation of Phase Transition in the Massive Schwinger Model

TL;DR

This paper uses quantum computing on a NISQ device to identify the critical point of a phase transition in the massive Schwinger model, aligning well with classical results.

Contribution

It introduces a momentum space lattice formalism and demonstrates quantum computation of the phase transition point on a NISQ device.

Findings

Critical point at m/e ≈ 0.32 identified after error mitigation.

Results agree with classical numerical estimate of m/e ≈ 0.3335.

Shows feasibility of quantum simulation for phase transitions in quantum field theories.

Abstract

As pointed out by Coleman, physical quantities in the Schwinger model depend on a parameter $\theta$ that determines the background electric field. There is a phase transition for $\theta = \pi$ only. We develop a momentum space formalism on a lattice and use it to perform a quantum computation of the critical point of this phase transition on the NISQ device IMB Q Lima. After error mitigation, our results give strong indication of the existence of a critical point at $m/e\simeq 0.32$, where $m$ is the bare fermion mass and $e$ is the coupling strength, in good agreement with the classical numerical result $m/e \simeq 0.3335$.