Berry´s phase and removal of time-reversal symmetry by magnetic fields

Summary form only given. Phase conjugation is a nonlinear optical process that reverses the wavefront of a beam of light and which is mathematically analogous to the time-reversal of the wave. It is therefore natural to ask whether this analogy is physically significant. Because photons are bosons, quantum properties can emerge at the macroscopic level. Such a quantum-mechanical property is the geometric (Berry´s) phase acquired by cycling a photon on a closed circuit in phase space (which for polarization states is the Poincare sphere). Berry´s phase can be considered to be a record of the system history and therefore can be used to gain insight into its time-invariance properties. Also, the large magneto-optical effects experienced by photorefractive diluted magnetic semiconductors suggest a natural experimental situation for probing the nature of time reversal in phase conjugation by studying the effect of applied magnetic fields on phase-conjugate light. It has been previously shown that the application of a magnetic field leads to the quenching of the time-reversed polarization state of the phase-conjugate beam in four-wave mixing experiments. We propose an experiment to further explore the influence of magnetic fields on time reversal.