Quasiparticles, coherence, and nonlinearity: Exact simulations of rf spectroscopy of strongly interacting one-dimensional Fermi gases

Abstract

We consider rf spectroscopy of ultracold Fermi gases by exact simulations of the many-body state and the coherent dynamics in one dimension. Deviations from the linear response sum rule result are found to suppress the pairing contribution to the rf line shifts. We compare the coherent rotation and quasiparticle descriptions of rf spectroscopy which are analogous to NMR experiments in superfluid 3 He and tunneling in solids, respectively. We suggest that rf spectroscopy in ultracold gases provides an interesting crossover between these descriptions that could be used for studying decoherence in quantum measurement, in the context of manybody quantum states.

Temperature and Final State Effects in Radio Frequency Spectroscopy Experiments on Atomic Fermi Gases

“…This technique has been applied experimentally in a trap integrated [1,3] and tomographic [2] fashion. While early theoretical work [4,5] addressed trap effects, more recently attention has been on final state effects [6,7,8,9,10] although, unfortunately, only at low or zero temperature. Many have viewed the importance of these experiments as a means of quantitatively measuring the ground state pairing gap, thereby testing different approaches to BCS-BEC crossover.…”

Spectral Signatures of the Fulde-Ferrell-Larkin-Ovchinnikov Order Parameter in One-Dimensional Optical Lattices

“…We have derived J ↑/↓ (δ, k) and J ↑/↓ (δ) in the present case, following the approach [20,21]. This corresponds to the quasiparticle picture [22] where the RF field can be understood to create quasiparticle excitations by pair breaking rather than to induce coherent rotation of the internal states. It is valid when the final state interactions are negligible [23,24].…”