Thermodynamics and structures of binary atomic Bose-Fermi mixtures from path-integral approach

Wed, 06/12/2019 - 16:13

Title	Thermodynamics and structures of binary atomic Bose-Fermi mixtures from path-integral approach
Speaker	Prof.Chih-Chun Chien(University of California)
Time	11:00 AM	June 21, 2019	(	Fri	)
Venue	Rm 502
Contact	Dr. Ying-Cheng Chen

Abstract

Trapping and cooling atomic gases have brought us a versatile platform for studying quantum many-body phenomena such as Bose-Einstein condensation (BEC) and superfluidity. On the theoretical side, a mean-field theory of interacting Bose gases needs to satisfy a set of criteria. However, most generalizations of the Bogoliubov-type theories fail the test. Using a path-integral formalism with a scheme known as the large-N expansion, a mean-field theory satisfying all the criteria has been developed. I will summarize the large-N based theory and apply it to a binary mixture of bosons and fermions. At low temperatures, the bosons exhibit BEC while there is no interaction between the fermions. When the boson-fermion interaction is strong, the thermodynamic free energy of the mixture exhibits loop structures typical of phase separation. Different from liquid or solid mixtures, gaseous mixtures do not have fixed densities as the system phase separates, and they need to satisfy mechanical and diffusive equilibrium. By using the lever rule and local density approximation, I will show the equilibrium structures and phase diagrams of binary Bose-Fermi mixtures in box potential and harmonic trap.

Quantum Optics Laboratory