TIME-REVERSAL EFFECT IN THE MAGNETIZATION OF ATOMS IN A GAS BY A RESONANT LIGHT-PULSE IN THE PRESENCE OF A CONSTANT MAGNETIC-FIELD

It is demonstrated that an electric field E of an elliptically polariz ed pulse with a polarization vector 1(k lambda) and wave vector k coll inear to a constant magnetic field H induces a magnetic moment of an a tom with an isotropic initial state that has two substantially differe nt components proportional to axial vectors i[Ik lambdaIk lambda] and H/H. If an atom features a symmetry with respect to time reversal in the presence of E and H fields, then the above-specified components of the light-induced magnetic moment are represented by even and odd fun ctions of H and the resonance detuning, respectively The system under study retains its properties after the propagation of an elliptically polarized resonant pulse, although the latter gives rise to a relaxati on, which violates time-reversal symmetry due to spontaneous emission of an excited-state atom. Similar features are also observed for the d ensity of the Light-induced magnetic moment of an atomic gas in the pr esence of a constant magnetic field.