Optical Excitations in a Nonideal Bose Gas
Abstract
Optical excitations in a Bose gas are demonstrated to be sensitive to many-body effects. At low temperature the momentum relaxation is provided by momentum exchange collisions, rather than by elastic collisions. A collective excitation mode forms, which in a nondegenerate gas is manifest in a collision shift and dramatic narrowing of spectral lines. In the Bose-Einstein condensate state, each spectral line splits into two components. The doubling of the optical excitations results from the physics analogous to that of the second sound. We present a theory of the line doubling, and calculate optical absorption spectrum for a uniform density system.
- Publication:
-
Physical Review Letters
- Pub Date:
- July 1999
- DOI:
- 10.1103/PhysRevLett.83.6
- arXiv:
- arXiv:cond-mat/9812217
- Bibcode:
- 1999PhRvL..83....6O
- Keywords:
-
- Condensed Matter;
- Physics - Atomic Physics
- E-Print:
- 5 pages, 3 eps figures