Emission of entangled photons via the biexciton formation and decay in core/shell nanoplatelets

Quasi-two-dimensional nanoplatelets (NPLs) possess fundamentally different excitonic properties from zero-dimensional quantum dots including exceptionally narrow spectral features and large lateral carrier mobility. We numerically study carrier dynamics of individual CdSe/CdS NPLs in an optical microcavity and find the emitted photon statistics using the density matrix formalism. We find that, due to formation of biexcitons in an NPL and their subsequent decay, the emitted pairs of cavity photons are entangled at temperatures below 20 K. Under favorable conditions the photon pair can be nearly maximally entangled with the relative photon pair population ~0.5. We also show that second-order photon correlation (g⁽²⁾) can be used as a measure of the photon pair entanglement. At temperatures higher than 20 K, the photon entanglement is suppressed due to dephasing caused by thermal fluctuations. Finally, we discuss possible experiments, in which the NPL generated photon pair entanglement can be observed, as well as potential applications in integrated quantum photonics.