Spectral dependence of diffuse light dynamics in ultracold atomic ⁸⁵Rb

Abstract

We report a combined experimental and theoretical simulation of multiply scattered light dynamics in an ultracold gas of ⁸⁵Rb atoms. Measurements of the spectral dependence of the time-decay of the scattered light intensity, following pulsed excitation with near resonance radiation, reveals that the decay for long times is nearly exponential, with a decay constant that is largely independent of detuning from resonance. Monte Carlo simulations of the multiple scattering process show that, for large detunings, near resonance scattering of Fourier components of the excitation pulse plays a significant role in the effect. This interpretation is supported by the observations, and successful modelling, of beating between Rayleigh scattered light at the excitation carrier frequency with the Fourier components of the excitation pulse that overlap significantly with the atomic resonance.

Acknowledgments

Supported by the National Science Foundation (NSF-PHY-0355024), by the Russian Foundation for Basic Research (RFBR-05-02-16172-a) and by the North Atlantic Treaty Organization (PST-CLG-978468).