Impact of the Casimir-Polder Potential and Johnson Noise on Bose-Einstein Condensate Stability near Surfaces

TL;DR

This paper studies how surface-induced forces like Casimir-Polder potential and Johnson noise affect the stability and lifetime of Bose-Einstein condensates near microfabricated surfaces, revealing limits at micron-scale distances.

Contribution

It provides experimental insights into the effects of surface forces on BEC stability near silicon and copper surfaces at micron distances.

Findings

Trap lifetime drops below 1 second at 4 microns due to Johnson noise.

Dielectric surfaces do not significantly affect BEC stability until Casimir-Polder forces become dominant.

Surface-induced forces critically limit BEC proximity to microfabricated surfaces.

Abstract

We investigate the stability of magnetically trapped atomic Bose-Einstein condensates and thermal clouds near the transition temperature at small distances 0.5 microns < d < 10 microns from a microfabricated silicon chip. For a 2 microns thick copper film the trap lifetime is limited by Johnson-noise induced currents and falls below 1 s at a distance of 4 microns. A dielectric surface does not adversely affect the sample until the attractive Casimir-Polder potential significantly reduces the trap depth.