Klein-Tunneling of a Quasirelativistic Bose-Einstein Condensate in an Optical Lattice

TL;DR

This study demonstrates Klein-tunneling in a quasirelativistic Bose-Einstein condensate within an optical lattice, showing relativistic particles can penetrate barriers without exponential damping, unlike nonrelativistic particles.

Contribution

First experimental simulation of Klein-tunneling with ultracold atoms in a tunable optical lattice, bridging quantum simulation and relativistic quantum phenomena.

Findings

Significant barrier transmission observed only for relativistic dispersion.

Both relativistic and nonrelativistic cases studied, with tunneling only in the relativistic case.

Optical lattice effectively simulates relativistic wave equations.

Abstract

Optical lattices have proven to be powerful systems for quantum simulations of solid state physics effects. Here we report a proof-of-principle experiment simulating effects predicted by relativistic wave equations with ultracold atoms in a bichromatic optical lattice that allows for a tailoring of the dispersion relation. We observe the analog of Klein-tunneling, the penetration of relativistic particles through a potential barrier without the exponential damping that is characteristic for nonrelativistic quantum tunneling. Both linear (relativistic) and quadratic (nonrelativistic) dispersion relations are investigated, and significant barrier transmission is observed only for the relativistic case.