Electronic Resource
Springer
The European physical journal
189 (1966), S. 365-384
ISSN:
1434-601X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract We give a fully quantum mechanical treatment of the dissipation and fluctuation of aN-level system coupled to a short memory loss and pumping reservoir which may describe the optical pumping and the spontaneous emission as well as phonon interaction. A general procedure for eliminating the reservoir coordinates is developed where all interesting reservoir properties enter into some phenomenological constants describing a Markov process. General quantum mechanical expectation values are written in terms of a Wigner transition probability distribution for which a Fokker-Planck equation is stated. From that a quantum mechanical Langevin equation can be derived in a straightforward way. The Bloch equations follow by averaging over the reservoir fluctuations. The dissipation and fluctuation coefficients are calculated explicitly in all orders of perturbation theory for aN-level system. In the special case of 2 levels they contain the results ofSauermann who uses a disentangling method. Several connections between relaxation and noise are found, one of these results being equivalent to results ofHaken andWeidlich in a simultaneous paper, found by a different method in the full Heisenberg picture.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01375491
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