Digit quantum simulation of a fermion field in an expanding universe

TL;DR

This paper demonstrates how digital quantum simulations can effectively model fermion behavior in an expanding universe, revealing phenomena like momentum redshift and showcasing the method's utility for complex time-evolution problems.

Contribution

It introduces a quantum simulation framework for fermions in an expanding universe, highlighting its effectiveness and simplicity for studying non-equilibrium quantum phenomena.

Findings

Observation of momentum redshift effects

Analysis of fermion number density and correlations

Demonstration of quantum simulation advantages for time evolution

Abstract

Quantum simulation is a rapidly evolving tool with great potential for research at the frontiers of physics, and is particularly suited to be used in computationally intensive lattice simulations, such as problems with non-equilibrium. In this work, a basic scenario, namely free fermions in an expanding universe, is considered and quantum simulations are used to perform the evolution and study the phenomena involved. Using digital quantum simulations with the Jordan-Wigner transformation and Trotter expansion, the evolutions of fermion number density, correlation functions, polarization, and chiral condensation are analyzed. A spread out phenomenon can be observed in the simulation, which is a consequence of momentum redshift. This work also demonstrates the simplicity and convenience of using quantum simulations when studying time-evolution problems.