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A bright and fast source of coherent single photons


A single-photon source is an enabling technology in device-independent quantum communication1, quantum simulation2,3, and linear optics-based4 and measurement-based quantum computing5. These applications employ many photons and place stringent requirements on the efficiency of single-photon creation. The scaling on efficiency is typically an exponential function of the number of photons. Schemes taking full advantage of quantum superpositions also depend sensitively on the coherence of the photons, that is, their indistinguishability6. Here, we report a single-photon source with a high end-to-end efficiency. We employ gated quantum dots in an open, tunable microcavity7. The gating provides control of the charge and electrical tuning of the emission frequency; the high-quality material ensures low noise; and the tunability of the microcavity compensates for the lack of control in quantum dot position and emission frequency. Transmission through the top mirror is the dominant escape route for photons from the microcavity, and this output is well matched to a single-mode fibre. With this design, we can create a single photon at the output of the final optical fibre on-demand with a probability of up to 57% and with an average two-photon interference visibility of 97.5%. Coherence persists in trains of thousands of photons with single-photon creation at a repetition rate of 1 GHz.

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Fig. 1: Concept of the single-photon source.
Fig. 2: Measured flux of single photons.
Fig. 3: Quantum-optics characterization of the single-photon source.
Fig. 4: Stability and reproducibility of the single-photon source.

Data availability

The data that is presented in the main text can be downloaded from The data will be available after an embargo period of six months, which starts from the final publication date of the manuscript.

Code availability

The code that has been used for this work is available from the corresponding author upon reasonable request.


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We thank A. Brash, P. Lodahl, N. Sangouard and S. Starosielec for fruitful discussions. We acknowledge financial support from Swiss National Science Foundation project 200020_175748, NCCR QSIT and Horizon-2020 FET-Open Project QLUSTER. A.J. acknowledges support from the European Unions Horizon 2020 Research and Innovation Programme under Marie Skłodowska-Curie grant agreement no. 840453 (HiFig). S.R.V., R.S., A.L. and A.D.W. gratefully acknowledge support from DFH/UFA CDFA05-06, DFG TRR160, DFG project 383065199 and BMBF Q.Link.X.

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Authors and Affiliations



N.T., A.J., N.O.A. and D.N. carried out the microcavity experiments. M.C.L. characterized the quantum dots and optimized the photon counting hardware. N.T. and D.N. fabricated the curved mirror. D.N., A.L. and R.J.W. designed the heterostructure. D.N. developed the surface passivation technique. A.R.K., R.S., S.R.V., A.D.W. and A.L. fabricated the semiconductor device. A.J. developed the model of the excitation mechanism. D.N. carried out the numerical simulations of the microcavity mode. N.T., A.J. and R.J.W. wrote the paper with input from all authors.

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Correspondence to Alisa Javadi.

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Supplementary Information

Supplementary Sections I–VIII and Figs. 1–8.

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Tomm, N., Javadi, A., Antoniadis, N.O. et al. A bright and fast source of coherent single photons. Nat. Nanotechnol. 16, 399–403 (2021).

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