Motivated by the recent experimental progress in the study of
p-wave resonant Fermi gases, we investigate the normal-state properties of such a gas. We calculate the universal equation of state and the two
p-wave contacts that characterize the universal properties of the system, in good agreement with experiments. Furthermore our calculation obtains the superfluid transition temperature
Tc within the Nozi\`eres and Schmitt-Rink (NSR) scheme and determines the analytic expressions for
Tc in the weak-coupling limit. We show explicitly the nonperturbative nature of the effective range corrections.
We calculate the critical temperature for Bose-Einstein condensation in a gas of bosonic atoms across a Feshbach resonance and show how medium effects at negative scattering lengths give rise to pairs reminiscent of the ones responsible for fermionic superfluidity. We find that the formation of pairs leads to a large suppression of the critical temperature. Within the formalism developed by Nozi\`eres and Schmitt-Rink, the gas appears mechanically stable throughout the entire crossover region, but when interactions between pairs are taken into account we show that the gas becomes unstable close to the critical temperature. We discuss prospects of observing these effects in a gas of ultracold
133Cs atoms where recent measurements indicate that the gas may be sufficiently long lived to explore the many-body physics around a Feshbach resonance.
Motivated by recent advances in orbitally tuned Feshbach resonance experiments, we analyze the ground-state phase diagram and related low-energy excitation spectra of a d-wave interacting Bose gas. A two-channel model with d-wave symmetric interactions and background s-wave interactions is adopted to characterize the gas. The ground state is found to have three interesting superfluid phases: atomic, molecular, and atomic–molecular. In great contrast to what was previously known about the p-wave case, the atomic superfluid is found to be momentum-independent for the d-wave case discussed here. The Bogoliubov spectra above each superfluid phase are obtained both analytically and numerically.
We theoretically investigate the specific heat
CV at constant volume in the normal state of a
p-wave interacting Fermi gas. Including fluctuations in the
p-wave Cooper channel within the framework of the strong-coupling theory developed by Nozières and Schmitt-Rink, we clarify how
CV as a function of temperature varies, as one moves from the weak-coupling regime to the strong-coupling limit. In the weak-coupling regime,
CV is shown to be enhanced by
p-wave pairing fluctuations, near the superfluid phase transition temperature
Tc. Similar enhancement of
CV(T≃Tc) is also obtained in the strong-coupling regime, which, however, reflects that system is close an ideal Bose gas of
p-wave two-body bound molecules. Using these results, we classify the normal state into (1) the normal Fermi gas regime, (2) the
p-wave molecular Bose gas regime, and (3) the region between the two, where
p-wave pairing fluctuations are dominant. Since the current experiments can only access the normal phase of a
p-wave interacting Fermi gas, our results would be useful for experiments to understand strong-coupling properties of this Fermi system above
Tc.
Abstract Motivated by experiments with interacting quantum gases across high partial wave resonance, we investigate the thermodynamic properties and single-particle spectra of Bose gases in normal phase for different interaction strengths for both p- and d-wave interactions. The equation of state, contact density, momentum distributions and self-energies of single-particle Green’s functions are obtained in the spirit of ladder diagram approximations. The radio-frequency (RF) spectrum, as an important experimental approach for detecting Feshbach molecules or the interaction effect, is calculated at different temperatures. A reversed temperature dependence on the Bose–Einstein condensation side and Bardeen–Cooper–Schrieffer side is identified for both p- and d-wave interactions. An estimate for the signal of RF spectra under typical experimental conditions is also provided.
Motivated by recent experimental progresses, we investigate few-body properties of interacting spinless bosons near a
d-wave resonance. Using the Skorniakov-Ter-Martirosion (STM) equations, we calculate the scattering length between an atom and a
d-wave dimer, and we find that the atom-dimer scattering length is positive and is much smaller the result from the mean-field approximation. We also reveal unique properties of the three-body recombination rate for a degenerate Bose condensate near the
d-wave resonance. We find that the total recombination rate is nearly a constant at the quasibound side, in contrast to the behavior of a thermal gas near a high-partial-wave resonance. We also find that the recombination rate monotonically increases across the unitary point toward the bound side, which is due to the largely enhanced coupling between the atom and the
d-wave dimer with deeper binding energy. This monotonic behavior is also qualitatively different from that of a degenerate gas near an
s-wave resonance counterpart.