Down-converted photon pairs in a high-Q silicon nitride microresonator
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1.
California Institute of Technology
- 2. Anello Photonics, Santa Clara, CA, USA
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3.
University of California, Santa Barbara
Abstract
Entangled photon pairs from spontaneous parametric down-conversion (SPDC) are central to many quantum applications, SPDC is typically performed in non-centrosymmetric systems with an inherent second-order nonlinearity (χ(2)). We demonstrate strong narrowband SPDC with an on-chip rate of 0.8 million pairs per second in Si3N4. Si3N4 is the pre-eminent material for photonic integration and also exhibits the lowest waveguide loss (which is essential for integrated quantum circuits). However, being amorphous, silicon nitride lacks an intrinsic χ(2), which limits its role in photonic quantum devices. We enabled SPDC in Si3N4 by combining strong light-field enhancement inside a high optical Q-factor microcavity with an optically induced space-charge field. We present narrowband photon pairs with a high spectral brightness. The quantum nature of the down-converted photon pairs is verified through coincidence measurements. This light source, based on Si3N4 integrated photonics technology, unlocks new avenues for quantum systems on a chip.
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Acknowledgement
We thank G. Moody from UCSB and X. Yi from the University of Virginia for helpful comments. This work is supported by the Defense Advanced Research Projects Agency (Award No. D24AC00166-00, Sub Award No. KK2519), the Air Force Office of Scientific Research (FA9550-23-1-0587) and the Kavli Nanoscience Institute at Caltech.
Contributions
These authors contributed equally: Bohan Li, Zhiquan Yuan.
The concepts were developed by B.L., Z.Y. and K.V. Measurements and modelling were performed by B.L. and Z.Y. with the help of J.W., A.B. and T.X. The structures were designed and prepared by W.J. and J.G. A. Feshali and M.P. prepared samples and provided logistical support. All authors contributed to the writing of the manuscript. The project was supervised by A. Faraon, J.B., A.M. and K.V.
Data Availability
The data are clearly represented in Figs. 1–4 and Extended Data Figs. 1–3.
Code Availability
The code to produce the plots is available from the corresponding author (such as for comparison with a new platform).
Files
Additional details
- PMCID
- PMC11946901
- Defense Advanced Research Projects Agency
- KK2519 D24AC00166-00
- United States Air Force Office of Scientific Research
- FA9550-23-1-0587
- California Institute of Technology
- Kavli Nanoscience Institute -
- Accepted
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2025-01-16
- Available
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2025-03-19Published
- Caltech groups
- Kavli Nanoscience Institute, Division of Engineering and Applied Science (EAS)
- Publication Status
- Published