2005/08/08 by D. H. Santamore, Eddy Timmermans
Physics and Astronomy · #Bose–Einstein condensate #Boson #Cold Atom Physics and Bose-Einstein Condensates #Condensed matter physics #Fermi Gamma-ray Space Telescope #Fermi gas #Fermi liquid theory #Fermion #Physics #Physics of Superconductivity and Magnetism #Quantum mechanics #Quantum, superfluid, helium dynamics #Quasiparticle #Superconductivity #Superfluidity #Zero mode #Zero sound #cond-mat.stat-mech #physics.atom-ph
paper · pdf · doi:10.1103/physreva.72.053601
published as Phys. Rev. A 72 (5), 053601 (2005) · 13 pages, 6 figures
arxiv created 2005/08/08 · openalex publication_date 2005/11/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We investigate the collective excitations of a low-temperature dilute gas mixture that consists of a Bose-Einstein condensate (BEC) and a Fermi gas that is a normal (i.e., nonsuperfluid) Fermi liquid. We find that the BEC-mediated fermion-fermion interactions, as a consequence of retardation, can become repulsive and support a zero-sound mode that is essentially undamped. In addition, we find a damped zero-sound mode that can be described as a BEC sound mode modified by fermion-mediated boson-boson interactions, and we derive its decay rate caused by Landau damping. We study the mode structure of these excitations and find avoided-crossing behavior as well as a termination point. The collective-mode dynamics also reveals that phase separation sets in when the fermion-mediated boson-boson interaction destroys the stability of the homogeneous BEC. We estimate the time and length scales of the onset of the phase separation, and we discuss the feasibility of experimentally probing these consequences of mediated interactions.