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Photon blockade in an optical cavity with one trapped atom


At low temperatures, sufficiently small metallic1 and semiconductor2 devices exhibit the ‘Coulomb blockade’ effect, in which charge transport through the device occurs on an electron-by-electron basis3. For example, a single electron on a metallic island can block the flow of another electron if the charging energy of the island greatly exceeds the thermal energy. The analogous effect of ‘photon blockade’ has been proposed for the transport of light through an optical system; this involves photon–photon interactions in a nonlinear optical cavity4,5,6,7,8,9,10,11,12,13. Here we report observations of photon blockade for the light transmitted by an optical cavity containing one trapped atom, in the regime of strong atom–cavity coupling14. Excitation of the atom–cavity system by a first photon blocks the transmission of a second photon, thereby converting an incident poissonian stream of photons into a sub-poissonian, anti-bunched stream. This is confirmed by measurements of the photon statistics of the transmitted field. Our observations of photon blockade represent an advance over traditional nonlinear optics and laser physics, into a regime with dynamical processes involving atoms and photons taken one-by-one.

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Figure 1: The atomic level structure used for implementation of the photon blockade effect, and a simple diagram of the experiment.
Figure 2: Theoretical results for the transmission spectra and intensity correlation functions.
Figure 3: Experimental measurements of the intensity correlation function for incident excitation with polarization along ŷ and detection with orthogonal polarization .


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We gratefully acknowledge the contributions of J. McKeever and C. J. Hood. This research is supported by the National Science Foundation, by the Caltech MURI Center for Quantum Networks, and by the Advanced Research and Development Activity (ARDA).

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Correspondence to H. J. Kimble.

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Supplementary information

Supplementary Notes

The text of our Supplementary Information, describing thet the coupling used in the model Hamiltonian to determine the eigenvalues displayed in Fig. 1b of the main text. This file also contains Supplementary Figure S1 and Supplementary Figure S2. (PDF 160 kb)

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Birnbaum, K., Boca, A., Miller, R. et al. Photon blockade in an optical cavity with one trapped atom. Nature 436, 87–90 (2005).

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