Reversible tuning of quantum dot emission to caesium D₁ line

We describe a new method for reversible and bi-directional in-situ precision tuning of the wavelength of single photons emitted by a quantum dot embedded in a semiconductor nanowire, using the deposition of inert gas. This method, which can be reversed by increasing the temperature or using focused laser to evaporate the deposited gas, has allowed us to match the D₁ transition (∼895 nm) of cesium atom. We report the emitted photon characteristics including second-order correlation function g⁽²⁾(τ) and linewidth, as well as the lifetime of the quantum dot before and after the wavelength tuning. We also discuss our initial experiments studying interactions between the single photons and atomic ensembles.