Optical lattice quantum simulator for QED in strong external fields: spontaneous pair creation and the Sauter-Schwinger effect

TL;DR

This paper proposes an optical lattice quantum simulator using ultra-cold atoms to mimic quantum electrodynamics phenomena like spontaneous pair creation, enabling experimental exploration of effects that are difficult to observe directly.

Contribution

It introduces a novel quantum simulation approach for QED effects using ultra-cold atoms in optical lattices, bridging condensed matter physics and high-energy phenomena.

Findings

Design of a bichromatic optical lattice setup for simulating Dirac fermions

Theoretical demonstration of spontaneous pair creation analogue in the simulator

Potential for experimental realization of QED phenomena in tabletop experiments

Abstract

Spontaneous creation of electron-positron pairs out of the vacuum due to a strong electric field is a spectacular manifestation of the relativistic energy-momentum relation for the Dirac fermions. This fundamental prediction of Quantum Electrodynamics (QED) has not yet been confirmed experimentally as the generation of a sufficiently strong electric field extending over a large enough space-time volume still presents a challenge. Surprisingly, distant areas of physics may help us to circumvent this difficulty. In condensed matter and solid state physics (areas commonly considered as low energy physics), one usually deals with quasi-particles instead of real electrons and positrons. Since their mass gap can often be freely tuned, it is much easier to create these light quasi-particles by an analogue of the Sauter-Schwinger effect. This motivates our proposal of a quantum simulator in which excitations of ultra-cold atoms moving in a bichromatic optical lattice represent particles and antiparticles (holes) satisfying a discretized version of the Dirac equation together with fermionic anti-commutation relations. Using the language of second quantization, we are able to construct an analogue of the spontaneous pair creation which can be realized in an (almost) table-top experiment.