Pairing-gap, pseudogap, and no-gap phases in the radio-frequency spectra of a trapped unitary 6Li gas

Radio frequency spectra of a trapped unitary 6Li gas are reported and analyzed in terms of a theoretical approach that includes both final-state and trap effects. The different strength of the final-state interaction across the trap is crucial for evidencing two main peaks associated with two distinct phases residing in different trap regions. These are the pairing-gap and pseudo-gap phases below the critical temperature Tc, which evolve into the pseudo-gap and no-gap phases above Tc. In this way, a long standing puzzle about the interpretation of rf spectra for 6Li in a trap is solved.