Adjustable electromagnetically induced transparency and absorption, optical controlled-phase gate in semiconductor quantum wells

Abstract

We investigate theoretically both the linear and nonlinear properties of the probe and signal optical pulsed fields in a system of four-level coupled GaAs/AlGaAs quantum wells with spontaneous decay of the longitudinal optical phonons (SDLOP) between the lower excited state and the ground state levels. In the linear range, we predict the existence of electromagnetically induced absorption (EIA), and that it is possible to mutually convert from electromagnetically induced transparency to EIA by adjusting the coherent control of the control optical field and the SDLOP. In the nonlinear range, it is shown that by taking into account the influence of the SDLOP, the cross-Kerr nonlinearity of the probe and signal optical fields can be tremendously enhanced. Simultaneously, we obtain the presence of the suppression of self-Kerr optical absorption of the probe field. These characteristics are advantageous to enable the realization of efficient photon-photon entanglement, and generate conditional nonlinear phase shifts of order π. Thereafter, we present a feasible scheme to carry out a two-qubit optical controlled-phase gate by encoding the polarization state of the probe and signal optical fields. Utilizing the linear optics components, we can discriminate the maximal polarization-entangled state of such a two-qubit system. This proposal is potentially applicable to facilitate the realization of solid states mediated all-optical quantum computation and information processing.