Zeno and anti-Zeno effects for photon polarization dephasing - art. no. 042108

We discuss a simple, experimentally feasible scheme, which elucidates the p rinciples of controlling the reservoir spectrum and the spectral broadening incurred by repeated measurements. This control can yield either the inhib ition (Zeno effect) or the acceleration (anti-Zeno effect) of the quasiexpo nential decay of the observed state by means of frequent measurements. In t he discussed scheme, a photon is bouncing back and forth between two perfec t mirrors, each time passing a polarization rotator. The horizontal and ver tical polarizations can be viewed as analogs of an excited and a ground sta te of a two level system (TLS). A polarization beam splitter and an absorbe r for the vertically polarized photon are inserted between the mirrors, and effect measurements of the polarization. The polarization angle acquired i n the electrooptic polarization rotator can fluctuate randomly, e.g., via n oisy modulation. In the absence of an absorber the polarization randomizati on corresponds to TLS decay into an infinite-temperature reservoir. The non -Markovian nature of the decay stems from the many round trips required for the randomization. We consider the influence of the polarization measureme nts by the absorber on this non-Markovian decay, and develop a theory of th e Zeno and anti-Zeno effects in this system.