On the Goldstone mode in the stationary state of a nonequilibrium dissipative system
Abstract
The paper considers the WardTakahashi identities formulated in the close time path Green's function applied to the saturation state of a single mode laser. The formulation is used as a specific example of nonzero Goldstone modes with dissipation which are excited in a nonequilibrium stationary state with spacetime structure in consequence of spontaneous symmetry breaking. A generalized Goldstone theorem in a weak inhomogeneous dissipative system is established and the physical interpretation of the Goldstone mode is discussed. As a result of the Goldstone theorem, the pole in the Green's function of the laser light splits into two with equal weights, each corresponding to quanta with the same frequency but different dissipation. Together with the order parameter, these two kinds of quanta provide a complete description of the orderdisorder transition of the phase symmetry in the saturation state of the laser.
 Publication:

Acta Physica Sinica
 Pub Date:
 May 1980
 Bibcode:
 1980AcPSn..29..618Z
 Keywords:

 Energy Dissipation;
 Green'S Functions;
 Laser Modes;
 Laser Outputs;
 Nonequilibrium Radiation;
 Nonlinear Optics;
 OrderDisorder Transformations;
 Quantum Theory;
 Saturation;
 Lasers and Masers