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# Single artificial atoms in silicon emitting at telecom wavelengths

## Abstract

Given its potential for integration and scalability, silicon is likely to be a key platform for large-scale quantum technologies. Individual electron-encoded artificial atoms, formed by either impurities or quantum dots, have emerged as a promising solution for silicon-based integrated quantum circuits. However, single qubits featuring an optical interface, which is needed for long-distance exchange of information, have not yet been isolated in silicon. Here we report the isolation of single optically active point defects in a commercial silicon-on-insulator wafer implanted with carbon atoms. These artificial atoms exhibit a bright, linearly polarized single-photon emission with a quantum efficiency of the order of unity. This single-photon emission occurs at telecom wavelengths suitable for long-distance propagation in optical fibres. Our results show that silicon can accommodate single isolated optical point defects like in wide-bandgap semiconductors, despite a small bandgap (1.1 eV) that is unfavourable for such observations.

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## Data availability

Source data are provided with this paper. All other results are available from the corresponding author upon reasonable request.

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## Acknowledgements

We thank P. Valvin for his technical support and fruitful discussions, and C. L’Henoret for his technical support at the mechanics workshop. We acknowledge support from the French National Research Agency (ANR) through the PRCI projects ULYSSES (no. ANR-15-CE24-0027-01) and OCTOPUS (no. ANR-18-CE47-0013-01), the German Research Foundation (DFG) through the ULYSSES project and the European Union’s Horizon 2020 research and innovation programme through the FET-OPEN project NARCISO (no. 828890). P.P. and D.C. acknowledge GENCI for the use of French computational resources in CCRT and IDRIS supercomputer centres (grant no. 6107). A. Durand acknowledges support from the French DGA.

## Author information

Authors

### Contributions

A. Durand, I.R.-P., V.J., A. Dréau and G.C. designed the experimental set-up. T.H., A.B., S.P., J.M. and A.Y.K. prepared the samples. W.R., A. Durand and A. Dréau carried out the experiments. J.-M.G., D.C. and P.P. performed numerical simulations. W.R., A. Durand, J.-M.G., I.R.-P., B.G., M.A., V.J., A. Dréau and G.C. analysed the data. A. Dréau prepared the manuscript with contributions from I.R.-P., V.J. and G.C. All authors discussed the results and commented on the manuscript.

### Corresponding author

Correspondence to A. Dréau.

## Ethics declarations

### Competing interests

The authors declare no competing interests.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

## Extended data

### Extended Data Fig. 1 Analysis of the photodynamics of the G-center.

a, Simplified three-level model of the G-center under optical excitation. b, Second-order autocorrelation function $${g}_{{\rm{cor}}}^{(2)}(\tau )$$ with increasing laser excitation power (from bottom to top). Data are corrected from background counts (see Eq. (1)) and fitted with equation (3). c, Evolution of the rates Λ0 and Λ1 with increasing optical power. The dashed lines correspond to data fitting excluding the last point at 30 μW. d, The bunching amplitude decreases with increasing optical power. The dotted line is a guide to the eye. Error bars represent the standard error resulting from data fitting of b with Python lmfit package.

### Extended Data Fig. 2 Time-resolved PL counts recorded under pulsed laser excitation.

Histogram of the PL counts measured on a single defect under a 50-ps pulse laser excitation at 532 nm, with a periodicity of 270 ns. The measurement sequence was repeated 2.8 billion times. Counts are integrated in the window [0, 150] ns (shaded area), subtracted from noise counts (gray shaded area), and finally divided by the number of sweeps to get the probability to detect a photon per optical excitation Pphoton 4.1 10−4.

### Extended Data Fig. 3 Calculations of the photon collection efficiency by a NA=0.85 objective.

a, Scheme of the simulated structure. The emitter dipole is assumed to be lying in the plane perpendicular to the surface, as this configuration maximizes photon collection. b, Evolution of the collection efficiency ηcoll as a function of the depth d of the embedded emitter.

## Source data

### Source Data Fig. 1

Source data of the plots in Fig. 1.

### Source Data Fig. 2

Source data of the plots in Fig. 2.

### Source Data Fig. 3

Source data of the plots in Fig. 3.

### Source Data Extended Data Fig. 1

Source data of the plots in Extended Data Fig. 1.

### Source Data Extended Data Fig. 2

Source data of the plots in Extended Data Fig. 2.

### Source Data Extended Data Fig. 3

Source data of the plots in Extended Data Fig. 3.

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Redjem, W., Durand, A., Herzig, T. et al. Single artificial atoms in silicon emitting at telecom wavelengths. Nat Electron 3, 738–743 (2020). https://doi.org/10.1038/s41928-020-00499-0

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