Correlations and Counting Statistics of an Atom Laser

TL;DR

This paper reports on time-resolved detection and statistical analysis of an atom laser beam derived from a Bose-Einstein condensate, revealing Poissonian and thermal statistics through correlation measurements.

Contribution

It introduces a method for high-resolution counting of atoms from a BEC and characterizes the statistical properties of the atom laser and thermal beams.

Findings

Atom laser exhibits Poissonian counting statistics.

Thermal atomic beam shows bunching and Bose distribution.

Constant second-order correlation function for the atom laser.

Abstract

We demonstrate time-resolved counting of single atoms extracted from a weakly interacting Bose-Einstein condensate of $^{87}$Rb atoms. The atoms are detected with a high-finesse optical cavity and single atom transits are identified. An atom laser beam is formed by continuously output coupling atoms from the Bose-Einstein condensate. We investigate the full counting statistics of this beam and measure its second order correlation function $g^{(2)}(\tau)$ in a Hanbury Brown and Twiss type experiment. For the monoenergetic atom laser we observe a constant correlation function $g^{(2)}(\tau)=1.00\pm0.01$ and an atom number distribution close to a Poissonian statistics. A pseudo-thermal atomic beam shows a bunching behavior and a Bose distributed counting statistics.