Nanofiber-based optical trapping of cold neutral atoms

TL;DR

This paper reports on experimental techniques for optimizing nanofiber-based optical traps for cold atoms, including polarization control and atom loading methods, resulting in sub-Doppler temperatures and sub-Poissonian atom number distributions.

Contribution

It introduces methods to optimize nanofiber atom traps and demonstrates improved cooling and atom number statistics in such traps.

Findings

Achieved sub-Doppler temperatures in nanofiber traps

Demonstrated sub-Poissonian atom number distribution

Optimized polarization control via scattered light analysis

Abstract

We present experimental techniques and results related to the optimization and characterization of our nanofiber-based atom trap [Vetsch et al., Phys. Rev. Lett. 104, 203603 (2010)]. The atoms are confined in an optical lattice which is created using a two-color evanescent field surrounding the optical nanofiber. For this purpose, the polarization state of the trapping light fields has to be properly adjusted. We demonstrate that this can be accomplished by analyzing the light scattered by the nanofiber. Furthermore, we show that loading the nanofiber trap from a magneto-optical trap leads to sub-Doppler temperatures of the trapped atomic ensemble and yields a sub-Poissonian distribution of the number of trapped atoms per trapping site.