Interaction-assisted quantum tunneling of a Bose-Einstein condensate out of a single trapping well

TL;DR

This study experimentally investigates how interatomic interactions influence quantum tunneling of a Bose-Einstein condensate, revealing regimes of classical spilling, quantum tunneling, and loss-dominated decay, with tunneling rates exponentially related to chemical potential.

Contribution

It demonstrates the control and observation of interaction-dependent tunneling regimes in a Bose-Einstein condensate using a tailored trap setup.

Findings

Tunneling rate depends exponentially on chemical potential.

Identified three distinct decay regimes: classical spilling, quantum tunneling, and background loss.

Good agreement with numerical 3D Gross-Pitaevskii simulations.

Abstract

We experimentally study tunneling of Bose-condensed $^{87}$Rb atoms prepared in a quasi-bound state and observe a non-exponential decay caused by interatomic interactions. A combination of a magnetic quadrupole trap and a thin $1.3\mathrm{\mu m}$ barrier created using a blue-detuned sheet of light is used to tailor traps with controllable depth and tunneling rate. The escape dynamics strongly depend on the mean-field energy, which gives rise to three distinct regimes--- classical spilling over the barrier, quantum tunneling, and decay dominated by background losses. We show that the tunneling rate depends exponentially on the chemical potential. Our results show good agreement with numerical solutions of the 3D Gross-Pitaevskii equation.