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Moving Stationary State of Exciton–Phonon Condensate in Cu 2 O
Author(s) -
Roubtsov D.,
Lépine Y.
Publication year - 1998
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/(sici)1521-3951(199811)210:1<127::aid-pssb127>3.0.co;2-2
Subject(s) - exciton , semiclassical physics , phonon , physics , condensed matter physics , bose–einstein condensate , excitation , quantum mechanics , quantum
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 condensate 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.