J ul 1 99 8 Moving Stationary State of Exciton - Phonon Condensate in
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چکیده
We explore a simple theoretical model to describe the properties of Bose condensed para-excitons in Cu 2 O. Taking into account the exciton-phonon interaction and introducing a coherent phonon part of the moving condensate, we derive the dynamic equations for the exciton-phonon condensate. Within the Bose approximation for excitons, we discuss the conditions for the moving inhomogeneous con-densate to appear in the crystal. We calculate the condensate wave function and energy and a collective excitation spectrum in the semiclassical approximation. The stability conditions of the moving condensate are analyzed by use of Landau arguments , and two critical velocities appear in the theory. Finally, we apply our model to describe the recently observed interference between two coherent exciton-phonon packets in Cu 2 O.
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تاریخ انتشار 1998