Xiangying Hao

Dynamical control of soliton formation and propagation in a Y-type atomic system with dual ladder-type electromagnetically induced transparency

We have investigated the nonlinear interaction between a weak-pulsed probe field and a four-level Y-type atomic system with dual ladder-type electromagnetically induced transparency. Two strong coupling fields induce a quantum destructive interference effect which depletes the population in the two nearly degenerate uppermost levels of the system and dramatically enhances the linear as well as nonlinear dispersion while simultaneously significantly suppressing the probe field absorption. We present the semiclassical quantum analysis of the system. The perturbation method of multiple scales is used to derive a differential envelope equation that describes the propagation of the probe field in the Y-type atomic system. It is then demonstrated that bright and dark optical solitons can be formed in this system.

Controllable generation and propagation of ultraslow optical solitons via parameters management in a five-level hyper inverted-Y atomic system

The dynamics of generation and propagation of ultraslow optical solitons in a lifetime-broadened five-level hyper inverted-Y atomic system are investigated. Due to the novel absorption and dispersion properties of this system which provide the necessary ingredients for making the probe field propagate nearly transparent in three regimes, the generation of bright or dark optical solitons can be controlled with parameters management by actively manipulating the dispersion, the nonlinearity and the gain (absorption coefficient) via adjusting the corresponding one-, two- and three-photon detunings and the Rabi frequencies.

Polarization qubit phase gate between two far-infrared pulses in three-coupled quantum wells

The cross-Kerr nonlinearity arising between two far-infrared (FIR) pulses is investigated in a three-coupled-quantum-well (TCQW) structure based on intersubband transitions. The results show that the giant Kerr nonlinearity with a relatively large cross-phase-modulation phase shift can be used for realizing polarization quantum phase gate in this TCQW structure. Such a semiconductor system is much more practical than its atomic counterpart because of its flexible design and the wide tunable parameters. This protocol may have potential applications in FIR all-optical switch design and quantum information processing with solid-state materials.

Continuous-variable entanglement via an incoherent pump in a microwave-driven Λ-type single-atom laser

We investigate the generation and evolution of continuous-variable (CV) entanglement via an incoherent pump in a single-atom cavity electrodynamics (CQED) system. The atomic coherence in such a ? configuration is introduced by driving the lower two levels with a strong classical field of Rabi frequency ?m. It is shown that the intensity of the driving field can influence effectively the period of the entanglement between the two cavity modes.