Quantum dot polarisation converter in an optomechanical cavity

Abstract

We propose a scheme of a quantum photon polarisation converter, which is based on controlled electron – photon – phonon transitions in a hybrid semiconductor nanostructure. This structure consists of a GaAs/InAs quantum dot (QD) that has a parallelepiped shape and contains a single electron, and an optomechanical microcavity (MC) based on a photonic crystal (PC) that supports two orthogonally polarised photonic modes and one mechanical (phonon) mode. Within the framework of the microscopic theory, the QD and MC performance characteristics are found. Populations of states of the system as functions of time and its parameters are calculated. The principal possibility of photon polarisation conversion using transitions in a five-level resonance scheme for coherent (single-photon) and steady-state (subphoton) regimes is shown. The MC optical and mechanical spectra are simulated, and the PC structure parameters are selected to ensure the efficient operation of the converter.

Polarization converter of single photons on a two-dimensional quantum dot in an optical microresonator

“…Here, we consider a quantum polarization converter, which can function as a beam splitter and a router, or as a qubit for algorithms encoding information into spatial degrees of freedom of a photon. Previously, we proposed a five-level converter model based on a single-electron QD coupling to quantum fields of a two-mode MR and to a phonon mode, which was used as a mediator in the energy exchange between the electron and photon subsystems [12]. Below, we present an alternative conversion scheme, in which the mechanical degree of freedom does not participate, and weakening the selection rules for QD transitions that prevent the interaction of photons having different polarizations is achieved by rotating the QD and MR symmetry axes relative to each other.…”