Optical photons are superb carriers of quantum information. They are relatively immune to most sources of decoherence and can be easily manipulated to realize high-precision single-qubit gates. Moreover, recent theoretical work and proof-of-concept experiments have addressed the challenge of mediating two-photon interactions . The ability to efficiently implement entangling operations supports the idea that scalable quantum computation can be achieved using photons as qubits. However, key components still have to be developed to achieve scalable, fault-tolerant optical quantum computing. One of the remaining challenges is to realize high-efficiency sources of indistinguishable single photons.
A modern approach to single-photon sources are nano-impurities in a solid-state host (quantum dots, point defects in diamond, doped organic crystals, etc.). The impurities have atom-like emission due to localized electronic states and they are suitable for integration on photonic chips. The Quantum Nanophotonics group investigates single dibenzoterrylene (DBT) molecules in crystalline anthracene. DBT dopant molecules are optically stable even at room temperature  and emit with high efficiency (approx. 40%) in a lifetime-limited spectral line at cryogenic temperatures . These are characteristics of an excellent candidate for sources of indistinguishable photons.
My research focuses on integrating DBT doped anthracene crystals with optical structures on a chip. To collect indistinguishable photons with high efficiencies, the structures will have to enhance the molecular emission both spectrally and spatially. We are currently investigating whether this goal can be achieved by growing doped nano-crystals inside photonic nano-cavities.
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