We theoretically present that generation of entangled-photon pairs from biexcitons in a quantum well is dramatically enhanced by using a microcavity. It’s optimal condition is qualitatively understood from the characteristic feature of the cavity QED.
We theoretically investigate polarization-entangled-photon generation by using a quantum dot embedded in a microcavity. In the absence of a biexciton, two of the four Bell states can be generated by applying cross-circularly polarized laser fields because of a cavity quantum electrodynamics effect [Ajiki et al., New J. Phys. 11, 033033 (2009)]. In the presence of the biexciton state, the generation of these Bell states can be forbidden under specific conditions. Furthermore, another type of Bell state can be generated by applying cross-circularly polarized fields. Our results indicate that one can generate three different types of Bell-state photon pairs just by changing the frequencies of the applied fields.
Theoretical study on entangled photon generation from a quantum dot (QD) embedded in microcavity is briefly reviewed within a strong coupling regime. In this system, entangled photon pairs can be generated through the cascade photon emission via dressed states in the cavity quantum electrodynamics (CQED). Excitation levels of a QD are modeled by a V-type three-level system and four-level system including a biexciton. In contrast to the entangled-photon generation until now, all four Bell states can be generated from an identical cavity system by simply selecting applied-field polarizations and frequencies as characteristic features of the CQED. The CQED effects play a crucial role in providing a high degree of entanglement: (i) spectral fi ltering can be used to extract entangled photons due to the vacuum Rabi splitting and (ii) non-entangled co-polarized photons are strongly suppressed due to the photon blockade effect.
In this paper, we provide theoretical study on entangled photon generation by means of RHPS in a QD embedded in a microcavity. The emphasis lies on the photon blockade effect on efficient entangled photon generation with high degree of purity. Furthermore, we note that a biexciton plays only a minor role in entangled photon generation because of the characteristic excited states in the cavity QED. This is contrast to entangled photon generation in a semiconductor until now, in which excitation of biexciton is indispensable for the entangled photon generation.
Nonlinear optical response of cavity polaritons formed in high-g semiconductor microcavities has attracted much attention because of their potential applications to entangled-photon sources and other quantum information technologies. Theoretical ideas of entangled-photon generation, e.g., biexcitonic cavity quantum electrodynamics and polariton-polariton scattering, have been suggested, however these theories are limited in scope of target because they restrict two-exciton states to either biexciton or unbound two-exciton states. As for exciton system with small binding energy of biexciton, it is likely that the interplay between the biexciton and unbound two-exciton states have much impact on generation efficiency of entangled photons. The authors introduces a general model including both biexciton and unbound two-exciton states and discuss generation efficiency of entangled photons.