Perturbation-theory calculations of two-quantum relaxation processes

Tatsuo Yajima

The multiple quantum process in the off-resonant condition of the three-level gas maser is discussed. The intensity of the emission produced by this process is calculated by a perturbation theory and also by a more general treatment which is the application of Javan's theory to the off-resonant case. Some graphical representations of the signal line under off-resonant pumping are given for the purpose of comparison with experiment. The Doppler effect in three-level maser action is analyzed from both semiclassical and quantum mechanical points of view under the presence of collision relaxation. It was shown that in a saturation process between two levels, Doppler effect behaves as to contribute to both line-width and relaxation time for the transition, and that under strong pumping, Doppler effect in pumping transition has a marked influence on both intensity and shape of the signal line through the effect of multiple quantum transition.

Antonia Chimonidou, E. C. G. Sudarshan

We study the process by which quantum correlations are created when an interaction Hamiltonian is repeatedly applied to a system of two harmonic oscillators for some characteristic time interval. We show that, for the case where the oscillator frequencies are equal, the initial Maxwell-Boltzmann distributions of the uncoupled parts evolve to a new Maxwell-Boltzmann distribution through a series of transient Maxwell-Boltzmann distributions, or quasistationary, nonequilibrium states. Further, we discuss why the equilibrium reached when the two oscillator frequencies are unequal is not a thermal one. All the calculations are exact and the results are obtained through an iterative process, without using perturbation theory.

A.S. Davydov

B. Gurkut, J. P. Schermann, C. Audoin

A two-level quantum system is considered in which relaxation processes with characteristic time constants T1and T2are present. The shift in frequency due to perturbations at two different frequencies is calculated. The general result is experimentally verified for the\DeltaF = 1, \Deltam_{F} = 0transition of atomic hydrogen, when the frequency of the external perturbations is close to the unperturbed two-level transition frequency.

Adithya Kandhadai, Antony Valentini