Generation of pure quantum light in the solid-state
The ability to generate light in pure quantum states is central to the development of quantum-enhanced technologies. Recently, artificial atoms in the form of semiconductor quantum dots have emerged as an excellent platform for quantum light generation . By placing the quantum dot in an optical microcavity, pure dephasing phenomena are strongly suppressed and single photon wavepackets with very high quantum purity in the frequency domain are generated . This is obtained at high efficiency, which opens new possibilities for optical quantum protocols such as the resource efficient generation of linear cluster states .
We recently revisited the Hong-Ou-Mandel interference of indistinguishable photons to better understand the effects of imperfect purity  and explored new schemes to push further the source efficiency . Interestingly, this last study shows that we can turn the emitter imperfections and its coupling the solid-state environment into resources.
Finally, this high-quality artificial atom-photon interface allows us to investigate fundamental quantum optics. We recently demonstrated that the coherence imprinted at the atomic level can be transferred to the radiated field through spontaneous emission. We report on the direct generation of light pulses in a pure quantum superposition of vacuum and one-photon with a full control of their relative populations and phase .
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