Phase transition and storage of quantum optical information in spatially periodical atomic structure

Abstract

A new developed for storing quantum information on atomic polaritons being at thermal equilibrium is developed for the first time. We propose a new type of spatially periodic structure - polaritonic crystal (PolC) formed by trapped two-level atoms interacting with quantum electromagnetic field in one-dimensional array of tunnelcoupled microcavities, which allows polaritons to be fully localized. The quantum degeneracy and phase transition to superfluid (Bardeen-Cooper-Schrieffer-type) state for low branch polaritons is discussed. The principal result is that the group velocity of polaritons depends essentially on the order parameter of the system, i.e. on the average photon number in the cavity array. An algorithm for the spatially distributed writing, storing, and retrieving of quantum optical information using polariton wave packet propagated in the cavity array is examined. To take into account decoherence processes in polaritonic system the quantum Brownian particle model is discussed as well.