Gianluca Bertaina - Università di Milano #
Quantum phase transitions and momentum distributions in Bose-Fermi 
mixtures with resonant interactions #
We study a Bose-Fermi mixture with interspecies resonant interaction at 
zero temperature, by means of Quantum Monte Carlo methods. We explore 
the system from weak to strong boson-fermion interaction, for different 
concentrations of the bosons relative to the fermion component. For a 
boson density smaller than the fermion density, a first-order quantum 
phase transition is found from a state with condensed bosons immersed in 
a Fermi sea, to a Fermi-Fermi mixture of composite fermions and unpaired 
fermions. We obtain the equation of state and the phase diagram [1], and 
we find that the region of phase separation shrinks to zero for 
vanishing boson density, recovering the polaron-molecule transition. We 
study the peculiar role of interspecies interaction in the depletion of 
the bosonic condensate, both in the polaronic branch and in the 
molecular branch [2]. In the molecular limit we show the occurrence of 
an indirect Pauli exclusion effect on the bosonic momentum distribution 
function, which completely depletes the occupancy of small momenta.
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[1] G. Bertaina, E. Fratini, S. Giorgini, and P. Pieri, Phys. Rev. Lett. 
110, 115303 (2013).
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[2] A. Guidini, G. Bertaina, E. Fratini, and P. Pieri, Phys. Rev. A 89, 
023634 (2014).