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A photon–photon quantum gate based on Rydberg interactions


The interaction between Rydberg states of neutral atoms is strong and long-range, making it appealing to put it to use in the context of quantum technologies. Recently, first applications of this idea have been reported in the fields of quantum computation1 and quantum simulation2,3,4. Furthermore, electromagnetically induced transparency allows one to map these Rydberg interactions to light5,6,7,8,9,10,11,12,13,14,15. Here we exploit this mapping and the resulting interaction between photons to realize a photon–photon quantum gate16,17, demonstrating the potential of Rydberg systems as a platform also for quantum communication and quantum networking18. We measure a controlled-NOT truth table with a fidelity of 70(8)% and an entangling-gate fidelity of 63.7(4.5)%, both post-selected upon detection of a control and a target photon. The level of control reached here is an encouraging step towards exploring novel many-body states of photons or for future applications in quantum communication and quantum networking18.

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The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.


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This work was supported by Deutsche Forschungsgemeinschaft through Nanosystems Initiative Munich.

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All authors contributed extensively to the work presented here.

Correspondence to Stephan Dürr.

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Fig. 1: Atomic level schemes.
Fig. 2: Simplified scheme of the experimental set-up.
Fig. 3: Performance of the photon-photon gate.