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Journal of Experimental and Theoretical Physics

Rarefied Imperfect Bose Gas in a Field of Randomly Distributed Fixed Impurities

V. A. Gergel’, Rudolf F. Kazarinov, Robert A. Suris

Published Jan 1, 1970• 1 citation
OpenAlex

Abstract

of the behavior of a slightly imperfect Bose gas in a field of randomly distributed impuri­ties 1s cons1dered. The effect of the impurity atoms on the ground state of the system is determined and found to reduce to a local change in the density of the condensate near the impurity atoms. The spectrum a_nd attenuation of one-particle excitations are calculated. The spectrum of the long wavelength excita­

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of the behavior of a slightly imperfect Bose gas in a field of randomly distributed impuri­ties 1s cons1dered. The effect of the impurity atoms on the ground state of the system is determined and found to reduce to a local change in the density of the condensate near the impurity atoms. The spectrum a_nd attenuation of one-particle excitations are calculated. The spectrum of the long wavelength excita­
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The exact density of states for one particle in the field of an attractive $\ensuremath{\delta}$ impurity center is obtained from the system Green's function. The impurity is shown to introduce a bound state in the free-particle energy spectrum without any further modification. This result is then used to study the effects of the impurity on the thermodynamical properties of a gas of noninteracting bosons. The "Bose-Einstein phase transition" is not destroyed by the impurity, but a true condensation in position space occurs due to the existence of the bound state. The captured bosons form a cloud of well-localized particles modifying the macroscopic behavior of the gas for temperatures below a transition temperature Tc{T}_{c}Tc​. The constant-volume specific heat, the entropy, and the pressure are evaluated as functions of the temperature and of the energy of the bound state, Eb{E}_{b}Eb​. The transition temperature and the discontinuity of the specific heat at Tc{T}_{c}Tc​ are also obtained as a function of Eb{E}_{b}Eb​.