Luttinger's theorem and Phase Transitions in Bose-Fermi mixtures

Eric Duchon, Shizhong Zhang, S.-L. Chang +2 more

Subir Sachdev A, Kun Yang

We discuss ground state properties of a mixture of two fermion species which can bind to form a molecular boson. When the densities of the fermions are unbalanced, one or more Fermi surfaces can appear: we describe the constraints placed by Luttinger's theorem on the volumes enclosed by these surfaces in such Bose-Fermi mixtures. We also discuss the nature of the quantum phase transitions involving changes in the number of Fermi surfaces.

Takaaki Sogo, Peter Schuck, Mi­chael Urban

Boson-fermion pair correlations in a mixture are considered at zero temperature in the $T$-matrix approximation. Special attention is paid to the Luttinger theorem. In a strict random-phase approximation variant of the Nozi\`eres-Schmitt-Rink approach, it is shown that this theorem is respected also in the homogeneous infinite matter case. We calculate the corresponding occupation numbers of fermions and bosons and the condensate depletion. We also show that in the limit of very small boson density, our results are in good agreement with the results found in the literature for the Fermi polaron in strongly imbalanced Fermi-Fermi mixtures.

D. Petrellis, A. Leviatan, F. Iachello

Wen-Qiang Ning, Shi-Jian Gu, Yuguang Chen +2 more

We study the ground-state fidelity and entanglement of a Bose-Fermi mixture loaded in a one-dimensional optical lattice. It is found that the fidelity is able to signal quantum phase transitions between the Luttinger liquid phase, the density-wave phase, and the phase separation state of the system, and the concurrence, as a measure of the entanglement, can be used to signal the transition between the density-wave phase and the Ising phase.

J. M. J. van Leeuwen, E. G. D. Cohen