title: Spectrum of two-level systems with discrete frequency fluctuations.
abstract: We study, theoretically and experimentally, an ensemble of two-level systems coupled to an environment which induces random jumps in their resonant frequency. We present a closed-form formula for the spectrum in terms of the resonant frequency distribution and the Poisson rate constant. For a normal distribution the spectrum deviates from a generalized Gumbel function, a well-known result for continuous stochastic Gaussian processes. We perform experiments with optically trapped cold 87Rb atoms and show that the predictions of our theory for a 3D harmonic trap match the measured spectra without fitting parameters.
authors.affiliation: Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Yoav
authors.initials: Y
authors.lastname: Sagi
authors.forename: Rami
authors.initials: R
authors.lastname: Pugatch
authors.forename: Ido
authors.initials: I
authors.lastname: Almog
authors.forename: Nir
authors.initials: N
authors.lastname: Davidson