Single photon source and quantum communication method

摘要

The photon source comprises a quantum dot to which charge carriers are intermittently supplied to create an exciton or higher order exciton (eg a biexciton). The exciton decay emits a single photon or a series of single photons. The number of excess carriers is controlled by applying an electric field across the device, and a blocking filter or time gating receiver may be used to separate photons. The polarization state of the photon may be controlled for quantum communication applications. A quantum communication method is also disclosed, comprising; outputting a sequence of photons where a quantum state randomly switches between two non-orthogonal basis for each group of photons, the quantum state being fixed for all members of the group, sending one photon to a first detector and a second photon to a second detector, the first and second detector readings being transmitted over a classical link, and wherein the source instructs the detectors to retain results from the detector readings using the same basis as the sent photon.