Much like being slightly off the frequency of a radio station destroys radio reception, the quality of light-emitting technologies has, until now, been severely limited by random fluctuations in the frequency of the emitted photons. Scientists demonstrated how this photon detuning can be suppressed using a series of short, controlled pulses applied to the emitter. The elegant solution is robust and applicable for many quantum systems, removing a major roadblock on the way to implementing large-scale quantum networks. The heart of these quantum-enhanced technologies is the solid-state spin-carrying light emitters, such as quantum dots or nitrogen-vacancy centers in diamond. Their spins communicate via perfectly matched, indistinguishable photons. Random fluctuations of these photons, known as optical spectral diffusion, are caused by uncontrollable changes in the environment. Spectral diffusion greatly diminishes the frequency overlap of different emitters and destroys the efficiency of the photon-based interface. Improvements to manipulating light and matter at the quantum level by suppressing spectral diffusion will revolutionize technology in untold ways, and can greatly enhance the precision of clocks, the science of precise measurements, and spectroscopic tools.
Excited state of the solid-state emitter is shifted by random amount Δ from the desired position. The optical 180° control pulses are applied periodically, with a delay τ. In the rotating frame, each pulse swaps the ground and the excited state, reversing the detuning Δ → −Δ.
Suppressing Spectral Diffusion of Emitted Photons with Optical Pulses