Muoi Tran, M. V. N. Murthy, R. K. Bhaduri
Published 2000-08-07, updated 2000-09-05Version 2
We consider a small and fixed number of fermions (bosons) in a trap. The ground state of the system is defined at T=0. For a given excitation energy, there are several ways of exciting the particles from this ground state. We formulate a method for calculating the number fluctuation in the ground state using microcanonical counting, and implement it for small systems of noninteracting fermions as well as bosons in harmonic confinement. This exact calculation for fluctuation, when compared with canonical ensemble averaging, gives considerably different results, specially for fermions. This difference is expected to persist at low excitation even when the fermion number in the trap is large.
Comments: 20 pages (including 1 appendix), 3 postscript figures. An error was found in one section of the paper. The corrected version is updated on Sep/05/2000
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Number Fluctuation in an interacting trapped gas in one and two dimensions
Study of Kosterlitz-Thouless transition of Bose systems governed by a random potential using quantum Monte Carlo simulations
