Frequency-Stabilized Source of Single Photons from a Solid-State Qubit

Single-photon sources required for quantum communication and computation are commonly based on semiconductor quantum dots; however, charge fluctuations in the semiconductor lead to unwanted variations in the ``color'' (wavelength) of the emitted photons. Scientists use a hybrid system of a quantum dot and a constant-wavelength laser to measure and then cancel out fluctuations in the wavelength, generating a perfect stream of single photons of one color.