Polaritonic quantum memory with two-level systems

Generating efficient quantum memories is crucial for the future Information processing. One of the well-known methods for describing quantum memories and analyzing the nature of coupling between light and matter is Polariton model. We analyze a light storage protocol based on cavity arrays [1] in terms of two-level polaritons, which is different from the typical EIT polaritons [2]. The cavity array scheme moreover inspires us to propose a quantum memory scheme with atomic ensembles. The scheme [1] is based on two types of cavities, wave-guide and side cavities. The coupled system possesses two eigen-states (polaritons) corresponding to two different group velocities. One can launch the incoming light into one of these polaritons and changes its group velocity by adiabatic modulation of the detuning between side-cavities and waveguide-cavities. In principle, this allows us to reduce the group velocity to zero, while the adiabaticity guarantees that the eigen-states (polaritons) remain separated during the process. Based on the cavity array model, we introduce an ideal and reversible transfer technique for the quantum state between light and two level atoms. The method is based on the control of photon propagation in the medium, in which the group velocity could be manipulated by the detuning and adiabatically reduced to zero. We present a detailed analysis for this model based on polaritonic description. [1] M. F. Yanik, S. Fan, Physical Review Letters, 92, (2004). [2] M. Fleischhauer, M. D. Lukin, Phys. Rev. Lett. 84, 5094. (2000).