Calculation of the even-odd energy difference in superfluid Fermi systems using the pseudopotential theory

¹ Department of Physics of Complex Systems, Eötvös University - Pázmány P. Sétány 1/A, H-1117 Budapest, Hungary, EU
² HAS-ELTE Statistical and Biological Physics Research Group, Eötvös University - Pázmány P. Sétány 1/A, H-1117 Budapest, Hungary, EU
³ Research Institute for Solid State Physics and Optics - P. O. Box 49, H-1525 Budapest, Hungary, EU

^a csordas@tristan.elte.hu
^b ggg.maxwell1@gmail.com
^c psz@complex.elte.hu

Received: 8 September 2011
Accepted: 13 December 2011

Abstract

The pseudopotential theory is extended to the Bogoliubov-de Gennes equations to determine the excess energy when one atom is added to the trapped superfluid Fermi system with even number of atoms. Particular attention is paid to systems being at the Feshbach resonance point. The results for relatively small particle numbers are in harmony with the Monte Carlo calculations, but are also relevant for systems with larger particle numbers. Concerning the additional one-quasiparticle state we define and determine two new universal numbers to characterize its widths.