Temperature and final state effects in radio frequency spectroscopy experiments on atomic Fermi gases

Abstract

We present a systematic characterization of the radio frequency (RF) spectra of homogeneous, paired atomic Fermi gases at finite temperatures, $T$, in the presence of final state interactions. The spectra, consisting of possible bound states and positive as well as negative detuning ($ν$) continua, satisfy exactly the zeroth- and first-moment sum rules at all $T$. We show how to detect the $ν< 0$ continuum arising from thermally excited quasiparticles, which has not yet been seen experimentally. We explain semi-quantitatively recent RF experiments on "bound-bound" transitions and, thereby, predict the associated effects of varying temperature.