5 research outputs found
Another Formulation of the Wick's Theorem. Farewell, Pairing?
The algebraic formulation of Wick's theorem that allows one to present the
vacuum or thermal averages of the chronological product of an arbitrary number
of field operators as a determinant (permanent) of the matrix is proposed. Each
element of the matrix is the average of the chronological product of only two
operators. This formulation is extremely convenient for practical calculations
in quantum field theory and statistical physics by the methods of symbolic
mathematics using computers
Nonmonotonic Decay of Nonequilibrium Polariton Condensate in Direct-Gap Semiconductors
Time evolution of a nonequilibrium polariton condensate has been studied in
the framework of a microscopic approach. It has been shown that due to
polariton-polariton scattering a significant condensate depletion takes place
in a comparatively short time interval. The condensate decay occurs in the form
of multiple echo signals. Distribution-function dynamics of noncondensate
polaritons have been investigated. It has been shown that at the initial stage
of evolution the distribution function has the form of a bell. Then
oscillations arise in the contour of the distribution function, which further
transform into small chaotic ripples. The appearance of a short-wavelength wing
of the distribution function has been demonstrated. We have pointed out the
enhancement and then partial extinction of the sharp extra peak arising within
the time interval characterized by small values of polariton condensate density
and its relatively slow changes.Comment: 20 pages, LaTeX 2.09; in press in PR
Decay of non-equilibrium polariton condensate in semiconductors
Consiglio Nazionale delle Ricerche (CNR). Biblioteca Centrale / CNR - Consiglio Nazionale delle RichercheSIGLEITItal