Time-delayed intensity-interferometry of the emission from ultracold atoms in a steady-state magneto-optical trap

TL;DR

This paper demonstrates the use of time-delayed intensity interferometry to analyze photon emission from ultracold rubidium atoms, revealing detailed coherence dynamics and enabling temperature measurement of the atomic ensemble.

Contribution

It introduces a high-resolution TDII technique to study coherence and thermal properties of ultracold atomic ensembles in steady-state magneto-optical traps.

Findings

Second-order correlation function equals 2 at zero delay

Observation of Rabi oscillations lasting up to 5 periods

Temperature measurements consistent with standard methods

Abstract

An accurate measurement of the bunching of photons in the fluorescent emission from an ultracold ensemble of thermal 87Rb atoms in a steady-state magneto-optical trap is presented. Time-delayed-intensity-interferometry (TDII) performed with a 5-nanosecond time resolution yielded a second-order intensity correlation function that has the ideal value of 2 at zero delay, and that shows coherent Rabi oscillations of upto 5 full periods - much longer than the spontaneous emission lifetime of the excited state of Rb. The oscillations are damped out by ~150ns, and thereafter, as expected from a thermal source, an exponential decay is observed, enabling the determination of the temperature of the atomic ensemble. Values so obtained compare well with those determined by standard techniques. TDII thus enables a quantitative study of the coherent and incoherent dynamics, even of a large thermal ensemble of atomic emitters.