How to manipulate quantum bits with few photons. Few photon coherent control of an artificial atom

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Coherent manipulation of a solid-state artificial atom with few photons

V. Giesz, N. Somaschi, G. Hornecker, T. Grange, B. Reznychenko, L. De Santis, J. Demory, C. Gomez, I. Sagnes, A. Lemaître, O. Krebs, N. D. Lanzillotti-Kimura, L. Lanco, A. Auffeves & P. Senellart

Nature Communications 7, Article number: 11986 (2016)
doi: 10.1038/11986

 

In a quantum network based on atoms and photons, a single atom should control the photon state and, reciprocally, a single photon should allow the coherent manipulation of the atom. Both operations require controlling the atom environment and developing efficient atom–photon interfaces, for instance by coupling the natural or artificial atom to cavities. Before our work, much attention had been drown on manipulating the light field with atomic transitions, recently at the few-photon limit. We have studied the reciprocal operation and demonstrated the coherent manipulation of an artificial atom by few photons. We study a quantum dot-cavity system with a record cooperativity of 13. Incident photons interact with the atom with probability 0.95, which radiates back in the cavity mode with probability 0.96. Inversion of the atomic transition is achieved for 3.8 photons on average, showing that our artificial atom performs as if fully isolated from the solid-state environment.

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Figure: (a) Emission intensity as a function of the excitation power (top axis) and the average photon number n (bottom axis) sent on the device for two pulse durations (12 and 56 ps). (b) Calculated emission as a function of n for two pulse durations. (c) Calculated probability to find the QD in its excited state after the pulse as a function of n for 12 and 56 ps pulses.