GROUND STATE ENERGY OF BOSE-EINSTEIN CONDENSATION IN A DISORDERED SYSTEM

Adelchi Fabrocini

A. C. Wilson, Callum R. McKenzie

Thomas Jaeck, Joseph V. Pulé, Valentin Anatol'evich Zagrebnov

Virulh Sa‐Yakanit, Wattana Lim

A modeled Bose system consisting of N particles with two-body interaction confined within volume V under inhomogeneity of the system is investigated using the Feynman path integral approach. The two-body interaction energy is assumed to be dependent on the two-parameter interacting strength a and the correlation length l. The inhomogeneity of the system or the porosity can be represented as density [Formula: see text] with interacting strength b and correlation length L. The mean field approximation on the two-body interaction in the Feynman path integrals representation is performed to obtain the one-body interaction. This approximation is equivalent to the Hartree approximation in the many-body electron gas problem. This approximation has shown that the calculation can be reduced to the effective one-body propagator. Performing the variational calculations, we obtain analytical results of the ground state energy which is in agreement with that from Bugoliubov's approach.

Abdus Salam

The Bogoliubov theory of weakly interacting Bose gas is generalized to Bose-Einstein condensates (BEC) of particles with arbitrary integer spin in a magnetic eld. On the basis of the Bogoliubov method of quasiaverages, an equation for the condensate wave function is obtained. The ground state properties, thermodynamic stability, and excitation spectra of such BEC are studied. The obtained results are compared to spin-1 Bose condensate.

Luca Salasnich

We discuss the mean-field approximation for a trapped weakly-interacting Bose–Einstein condensate (BEC) and its connection with the exact many-body problem by deriving the Gross–Pitaevskii action of the condensate. The mechanics of the BEC in a harmonic potential is studied by using a variational approach with time-dependent Gaussian trial wave-functions. In particular, we analyze the static configurations, the stability and the collective oscillations for both ground-state and vortices.