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G. G. Gomes

Publications and source records attributed to G. G. Gomes.

2 recordsLinked to original sources

Dissipative Quantum Systems in ThermoField Dynamics

We investigate a class of microscopic systems in interaction with a macroscopic system in thermal equilibrium, following the construction of Dalibard, Dupont-Roc and Cohen-Tannoudji (DDC). By considering self-adjoint operators as elements of Schwinger's Measurement Algebra (SMA), we construct statistical mean values of the relevant observables as matrix elements in a suitable operator basis, which correspond to the vacuum states of ThermoField Dynamics (TFD).

quant-ph

The vacuum electromagnetic fields and the Schrodinger picture

Several authors have used the Heisenberg picture to show that the atomic transitions, the stability of the ground state and the position-momentum commutation relation [x,p]=ih, can only be explained by introducing radiation reaction and vacuum electromagnetic fluctuation forces. Here we consider the simple case of a nonrelativistic charged harmonic oscillator, in one dimension, to investigate how to take into account the radiation reaction and vacuum fluctuation forces within the Schrodinger picture. We consider the effects of both classical zero-point and thermal electromagnetic vacuum fields. We show that the zero-point electromagnetic fluctuations are dynamically related to the momentum operator p=-ih d/dx used in the Schrodinger picture. Consequently, the introduction of the zero-point electromagnetic fields in the vector potential A_x(t) used in the Schrodinger equation, generates ``double counting'', as was shown recently by A.J. Faria et al. (Physics Letters A 305 (2002) 322). We explain, in details, how to avoid the ``double counting'' by introducing only the radiation reaction and the thermal electromagnetic fields into the Schrodinger equation.

quant-ph