Quantum phases in resonantly-interacting gases

Herman C. W. Beijerinck, S. J. J. M. F. Kokkelmans, Bout Marcelis

Tao Shi, S.-H. Zou, Hui Hu +2 more

The superfluid phases in resonant dipolar Fermi gases are investigated by the standard mean-field theory. In contrast to the crossover from Bose-Einstein condensation (BEC) to Bardeen-Cooper-Schrieffer superfluid in Fermi gases with isotropic interactions, resonant dipolar interaction leads to two completely different BEC phases of the tight-binding Fermi molecules on both sides of the resonance, which are characterized by two order parameters with distinct internal symmetries. We point out that, near the resonances, the two competitive phases can coexist, and an emergent relative phase between the two order parameters spontaneously breaks time-reversal symmetry, which could be observed in momentum resolved rf spectroscopy.

Yin Lan

Feshbach resonance is currently a very hot topic in the area of Bose-Einstein condensation, and has already been observed in most low\|temperature alkali gases. In these systems the interaction between atoms can be tuned from strong repulsion to strong attraction. A detailed overview is guven of the Feshbach resonance and two of its most important aspects, the superfluid phase in Fermi gases and the strong\|interaction regime in Bose gases.

R. Citro, Chiara Menotti, Anna Minguzzi +1 more

Dmitry Miserev, Jelena Klinovaja, Daniel Loss

Fermions in a Fermi gas obey the Pauli exclusion principle restricting any two fermions from occupying the same quantum state. Strong interactions between fermions can completely change the properties of the Fermi gas. In our theoretical study we find an exotic quantum phase in strongly interacting Fermi gases subject to a certain condition imposed on the Fermi surfaces that we call the Fermi surface resonance. The phase is quantum critical in time and space and can be identified by the power-law dependence of the spectral density in frequency and momentum. The linear-response functions are singular in the static limit and at the Kohn anomalies. We analyze the quantum critical state at finite temperatures $T$ and finite size $L$ of the Fermi gas and provide a qualitative $L\ensuremath{-}T$ phase diagram. The quantum critical phase can be experimentally found in typical semiconductor heterostructures.