Quantum Optics Semiar by N. Akopian – Niels Bohr Institute - University of Copenhagen

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Quantum Optics Semiar by N. Akopian

Artificial atoms that emit photons with identical frequencies play a key role in implementation of optical quantum networks, teleportation and quantum repeaters. We present a hybrid semiconductor-atomic system in which a single artificial atom generates photons with an absolute frequency that is locked to an optical transition in a natural atom. The radiative transitions of specially designed gallium-arsenide quantum dots (artificial atoms) are tuned and frequency-locked to the D2 transitions of rubidium atoms (natural atoms). Moreover, we show that the method is robust and immune to drifts and fluctuations of the environment, such as slow spectral wandering. Our demonstration is crucial for realization of a large number of universally-indistinguishable solidstate systems at arbitrary remote locations, where frequency-locked artificial atoms might become a fundamental ingredient.

Further, we use our hybrid system for slowing down single photons emitted from a single quantum dot. We take advantage of a double absorption resonance in rubidium vapor to create a slow-light medium. We reduce the velocity of single photons down to 3.3% of the speed of light in vacuum and demonstrate a storage of a single photon for 15 times its temporal width. These results pave the way towards implementation of quantum memories and quantum repeaters where single photons are generated on demand from a semiconductor source.  

[1] N. Akopian et al., Nature Photonics 5, 230 (2011).

[2] N. Akopian et al., submitted.