2003/05/31 by Lincoln D. Carr, L. D. Carr, Thomas Bourdel +3
Physics and Astronomy · #Advanced Thermodynamics and Statistical Mechanics #Cold Atom Physics and Bose-Einstein Condensates #Quantum, superfluid, helium dynamics #cond-mat.soft
paper · pdf · doi:10.1103/physreva.69.033603
published as Phys. Rev. A 69, 033603 (2004) · 14 pages, 7 figures. Phys. Rev. A in press
arxiv created 2004/02/23 · openalex publication_date 2004/03/09 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
It has been suggested by Timmermans [Phys. Rev. Lett. 87, 240403 (2001)] that loss of fermions in a degenerate system causes strong heating. We address the fundamental limit imposed by this loss on the temperature that may be obtained by sympathetic cooling of fermions by bosons. Both a quantum Boltzmann equation and a quantum Boltzmann master equation are used to study the evolution of the occupation number distribution. It is shown that, in the thermodynamic limit, the Fermi gas cools to a minimal temperature kBT∕\ensuremathμ\ensuremath∝(\ensuremathγloss∕\ensuremathγcoll)0.44, where \ensuremathγloss is a constant loss rate, \ensuremathγcoll is the bare fermion-boson collision rate not including the reduction due to Fermi statistics, and \ensuremathμ\ensuremath∼kBTF is the chemical potential. It is demonstrated that, beyond the thermodynamic limit, the discrete nature of the momentum spectrum of the system can block cooling. The unusual nonthermal nature of the number distribution is illustrated from several points of view: the Fermi surface is distorted, and in the region of zero momentum the number distribution can descend to values significantly less than unity. Our model explicitly depends on a constant evaporation rate, the value of which can strongly affect the minimum temperature.