No abstract

This paper theoretically studies the coherent control of photon transmission along the coupled resonator optical waveguide (CROW) by doping artificial atoms in hybrid structures. We provide the several approaches correspondingly based on the mean field method and spin wave theory et al . In the present paper we adopt the two-time Green function approach to study the coherent transmission photon in a CROW with homogeneous couplings, each cavity of which is doped by a two-level artificial atom. We calculate the two-time correlation function for photon in the weakcoupling case. Its poles predict the exact dispersion relation, which results in the group velocity coherently controlled by the collective excitation of the doping atoms. We emphasize the role of the population inversion of doping atoms induced by some polarization mechanism.

We investigate an anti-Zeno phenomenon as well as a quantum Zeno effect for the irreversible quantum tunneling from a quantum dot to a ring array of quantum dots. By modeling the total system with the Anderson-Fano-Lee model, it is found that the transition from the quantum Zeno effect to quantum anti-Zeno effect can happen by adjusting magnetic flux and gate voltage.

The transfer of optical vortices is studied based on double two-photon processes in a four-level diamond configuration system. A pair of strong fields are applied to prepare atomic coherence, while two weak probe fields are coupled with the other two transitions. When the two-photon resonances are satisfied, the analytical results for the intensities of the probe fields are calculated using perturbation theory and an adiabatic approximation approach. Our results explore whether the orbital angular momentum of an input probe beam or the second control field can be transferred to the generated probe field, and this is verified by numerical simulation. It is interesting that as the intensities of the control fields increase, the propagation of probe beams exhibits oscillation behaviors only when the one-photon detuning is nonzero. Furthermore, we show that the absorption losses are minimized, and the transfer efficiency is enhanced by appropriately modifying the one-photon detuning together with the control-field Rabi frequencies.

We explore the concept that the Raman process can be used as an effective way for transfer of optical vortices. In a four-level atomic system, two strong fields are applied to form a Λ-type subsystem while two probe fields couple to the other cascade transitions. It is found that the optical vortex of a control field can be transferred to a generated probe beam based on four-wave mixing processes, wherein the one-photon detuning plays an important role in minimizing the losses. On the other hand, when the control fields have no vortices, the transfer is realized between two probe beams for intermediate values of atomic coherence induced by the Raman process, vanishing both for the minimal value 0 and for the maximal values ±0.5. We have also analyzed the spatial structures of the propagating probe beams with optical vortices at the entrance, displaying that the information of winding numbers is hidden behind the intensity distributions and corresponding phase patterns. This may find potential applications in quantum information storage.