Parts | Days | Selection | Search | Downloads | Help

Q: Quantenoptik und Photonik

Q 18: Quantengase II

Q 18.6: Talk

Tuesday, March 23, 2004, 12:15–12:30, HS 225

Bose-Einstein Condensation Temperature of a Homogenous Weakly Interacting Bose Gas — •Boris Kastening — Institut für Theoretische Physik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin

The shift of the transition temperature of a homogenous Bose gas of particle density n due to a weak interaction, parametrized by the scattering length a, has the form Δ T_c/T₀=c₁an^1/3+[c₂′ln(an^1/3)+c₂″](an^1/3)²+⋯. While c₂′ is exactly known, c₁ and c₂″ depend on critical fluctuations and have to be determined by non-perturbative methods. We use variational perturbation theory through seven loops to determine c₁ [1] and the non-perturbative contribution to c₂″ [2]. The latter contribution also provides the only non-perturbative input needed for the corresponding expansion through second order in an arbitrarily wide harmonic trap.

[1] B.Kastening, Phys.Rev.A 68, 061601(R) (2003) [cond-mat/0303486]; cond-mat/0309060.

[2] B.Kastening, in preparation.