High-efficiency vertical emission spin-photon interface for scalable quantum memories
Summarize this article with:
AbstractWe present an efficient spin-photon interface for free-space vertical emission coupling. Using a dipole model, we show that our design achieves a far-field collection efficiency of 96% at the numerical aperture of 0.7 with a 95% overlap to a Gaussian mode. Our approach is based on a dual perturbation layer design. The first perturbation layer extracts and redirects the resonant mode of a diamond microdisk resonator around the optical axis. The second perturbation layer suppresses side lobes and concentrates most of the light intensity near the center. This dual-layer design enhances control over the farfield pattern and also reduces alignment sensitivity. Additionally, the implemented dipole model performs calculations $3.2$${\times}$$10^6$ times faster than full-wave FDTD simulations. These features make the design promising for quantum information applications.Popular summaryQuantum networks require devices that can reliably transfer quantum information from a stationary qubit to a traveling photon. Solid-state color centers in diamond are attractive candidates because they can store spin information for long times and emit photons compatible with optical networking. A major challenge, however, is getting those photons out efficiently and in a well-controlled optical mode. In this work, we propose a nanophotonic interface that addresses this challenge using a diamond microdisk coupled to two vertically stacked grating layers. The device is designed to funnel emission from a color center into a nearly Gaussian beam emitted normal to the chip surface. This vertical geometry is especially attractive for scalable quantum memories, since it is compatible with free-space collection and multiplexed architectures. Our design combines strong light-matter interaction with efficient out-coupling. Numerical optimization predicts a Purcell enhancement of about 62, collection efficiency up to 96% for a numerical aperture of 0.7, and mode overlap around 95% with an ideal Gaussian beam. The second grating layer plays an important role: besides improving beam quality, it also makes the device more tolerant to emitter misalignment and dipole-orientation uncertainty. These results suggest that vertically emitting diamond nanophotonic structures could provide an efficient and scalable spin-photon interface for future quantum repeater and quantum memory platforms.► BibTeX data@article{MirzaeiGhormish2026highefficiency, doi = {10.22331/q-2026-03-20-2035}, url = {https://doi.org/10.22331/q-2026-03-20-2035}, title = {High-efficiency vertical emission spin-photon interface for scalable quantum memories}, author = {Mirzaei-Ghormish, Siavash and Bennett, Jeddy and Camacho, Ryan M.}, journal = {{Quantum}}, issn = {2521-327X}, publisher = {{Verein zur F{\"{o}}rderung des Open Access Publizierens in den Quantenwissenschaften}}, volume = {10}, pages = {2035}, month = mar, year = {2026} }► References [1] Kimble, H. J. The quantum internet. Nature. 453, 1023-1030 (2008). https://doi.org/10.1038/nature07127 [2] Gottesman, D., Jennewein, T. & Croke, S. Longer-baseline telescopes using quantum repeaters.
Physical Review Letters. 109, 070503 (2012). https://doi.org/10.1103/PhysRevLett.109.070503 [3] Bersin, E., Sutula, M., Huan, Y., Suleymanzade, A., Assumpcao, D., Wei, Y., Stas, P., Knaut, C., Knall, E., Langrock, C. et al., Telecom networking with a diamond quantum memory. PRX Quantum. 5, 010303 (2024). https://doi.org/10.1103/PRXQuantum.5.010303 [4] Chen, K., Dhara, P., Heuck, M., Lee, Y., Dai, W., Guha, S. & Englund, D. Zero-added-loss entangled-photon multiplexing for ground-and space-based quantum networks.
Physical Review Applied. 19, 054029 (2023). https://doi.org/10.1103/PhysRevApplied.19.054029 [5] Li, L., De Santis, L., Harris, I., Chen, K., Christen, I., Trusheim, M., Han, R. & Englund, D. Heterogeneous integration of spin-photon interfaces with a scalable CMOS platform. CLEO: Fundamental Science. pp. FW3K-2 (2024). https://doi.org/10.1364/CLEO_FS.2024.FW3K.2 [6] Iwasaki, T., Miyamoto, Y., Taniguchi, T., Siyushev, P., Metsch, M., Jelezko, F. & Hatano, M. Tin-vacancy quantum emitters in diamond.
Physical Review Letters. 119, 253601 (2017). https://doi.org/10.1103/PhysRevLett.119.253601 [7] Görlitz, J., Herrmann, D., Thiering, G., Fuchs, P., Gandil, M., Iwasaki, T., Taniguchi, T., Kieschnick, M., Meijer, J., Hatano, M. et al., Spectroscopic investigations of negatively charged tin-vacancy centres in diamond. New Journal of Physics. 22, 013048 (2020). https://doi.org/10.1088/1367-2630/ab6631 [8] Burek, M., Chu, Y., Liddy, M., Patel, P., Rochman, J., Meesala, S., Hong, W., Quan, Q., Lukin, M. & Lončar, M. High quality-factor optical nanocavities in bulk single-crystal diamond. Nature Communications. 5, 5718 (2014). https://doi.org/10.1038/ncomms6718 [9] Wan, N., Mouradian, S. & Englund, D. Two-dimensional photonic crystal slab nanocavities on bulk single-crystal diamond.
Applied Physics Letters. 112, 141102 (2018). https://doi.org/10.1063/1.5021349 [10] Mouradian, S., Wan, N., Schröder, T. & Englund, D. Rectangular photonic crystal nanobeam cavities in bulk diamond.
Applied Physics Letters. 111, 021103 (2017). https://doi.org/10.1063/1.4992118 [11] Saggio, V., Errando-Herranz, C., Gyger, S., Panuski, C., Prabhu, M., De Santis, L., Christen, I., Ornelas-Huerta, D., Raniwala, H., Gerlach, C. et al., Cavity-enhanced single artificial atoms in silicon. Nature Communications. 15, 5296 (2024). https://doi.org/10.1038/s41467-024-49302-0 [12] Hausmann, B., Bulu, I., Venkataraman, V., Deotare, P. & Lončar, M. Diamond nonlinear photonics. Nature Photonics. 8, 369-374 (2014). https://doi.org/10.1038/nphoton.2014.72 [13] Ruf, M., Weaver, M., Dam, S. & Hanson, R. Resonant excitation and Purcell enhancement of coherent nitrogen-vacancy centers coupled to a Fabry–Perot microcavity.
Physical Review Applied. 15, 024049 (2021). https://doi.org/10.1103/PhysRevApplied.15.024049 [14] Janitz, E., Ruf, M., Dimock, M., Bourassa, A., Sankey, J. & Childress, L. Fabry–Perot microcavity for diamond-based photonics. Physical Review A. 92, 043844 (2015). https://doi.org/10.1103/PhysRevA.92.043844 [15] Li, L., Chen, E., Zheng, J., Mouradian, S., Dolde, F., Schröder, T., Karaveli, S., Markham, M., Twitchen, D. & Englund, D. Efficient photon collection from a nitrogen vacancy center in a circular bullseye grating. Nano Letters. 15, 1493-1497 (2015). https://doi.org/10.1021/nl503451j [16] Li, L., Schröder, T., Chen, E., Walsh, M., Bayn, I., Goldstein, J., Gaathon, O., Trusheim, M., Lu, M., Mower, J. et al. Coherent spin control of a nanocavity-enhanced qubit in diamond. Nature Communications. 6, 6173 (2015). https://doi.org/10.1038/ncomms7173 [17] Duan, Y., Chen, K., Englund, D. & Trusheim, M. A vertically-loaded diamond microdisk resonator spin-photon interface. Optics Express. 29, 43082-43090 (2021). https://doi.org/10.1364/OE.442834 [18] Flores, H., Layton, S., Englund, D. & Camacho, R. Alignment-free coupling to arrays of diamond microdisk cavities with fabrication tolerant spin-photon interfaces. Optics Express. 32, 12054-12064 (2024). https://doi.org/10.1364/OE.515620 [19] Claudon, J., Bleuse, J., Malik, N., Bazin, M., Jaffrennou, P., Gregersen, N., Sauvan, C., Lalanne, P. & Gérard, J. A highly efficient single-photon source based on a quantum dot in a photonic nanowire. Nature Photonics. 4, 174-177 (2010). https://doi.org/10.1038/nphoton.2009.287x [20] Reimer, M., Bulgarini, G., Akopian, N., Hocevar, M., Bavinck, M., Verheijen, M., Bakkers, E., Kouwenhoven, L. & Zwiller, V. Bright single-photon sources in bottom-up tailored nanowires. Nature Communications. 3, 737 (2012). https://doi.org/10.1038/ncomms1746 [21] Gschrey, M., Thoma, A., Schnauber, P., Seifried, M., Schmidt, R., Wohlfeil, B., Krüger, L., Schulze, J., Heindel, T., Burger, S. et al., Highly indistinguishable photons from deterministic quantum-dot microlenses utilizing three-dimensional in situ electron-beam lithography. Nature Communications. 6, 7662 (2015). https://doi.org/10.1038/ncomms8662 [22] Wan, N., Shields, B., Kim, D., Mouradian, S., Lienhard, B., Walsh, M., Bakhru, H., Schröder, T. & Englund, D. Efficient extraction of light from a nitrogen-vacancy center in a diamond parabolic reflector. Nano Letters. 18, 2787-2793 (2018). https://doi.org/10.1021/acs.nanolett.7b04684 [23] Zhu, J., Cai, X., Chen, Y. & Yu, S. Theoretical model for angular grating-based integrated optical vortex beam emitters. Optics Letters. 38, 1343 (2013). https://doi.org/10.1364/OL.38.001343Cited byCould not fetch Crossref cited-by data during last attempt 2026-03-20 11:30:43: Could not fetch cited-by data for 10.22331/q-2026-03-20-2035 from Crossref. This is normal if the DOI was registered recently. Could not fetch ADS cited-by data during last attempt 2026-03-20 11:30:43: No response from ADS or unable to decode the received json data when getting the list of citing works.This Paper is published in Quantum under the Creative Commons Attribution 4.0 International (CC BY 4.0) license. Copyright remains with the original copyright holders such as the authors or their institutions. AbstractWe present an efficient spin-photon interface for free-space vertical emission coupling. Using a dipole model, we show that our design achieves a far-field collection efficiency of 96% at the numerical aperture of 0.7 with a 95% overlap to a Gaussian mode. Our approach is based on a dual perturbation layer design. The first perturbation layer extracts and redirects the resonant mode of a diamond microdisk resonator around the optical axis. The second perturbation layer suppresses side lobes and concentrates most of the light intensity near the center. This dual-layer design enhances control over the farfield pattern and also reduces alignment sensitivity. Additionally, the implemented dipole model performs calculations $3.2$${\times}$$10^6$ times faster than full-wave FDTD simulations. These features make the design promising for quantum information applications.Popular summaryQuantum networks require devices that can reliably transfer quantum information from a stationary qubit to a traveling photon. Solid-state color centers in diamond are attractive candidates because they can store spin information for long times and emit photons compatible with optical networking. A major challenge, however, is getting those photons out efficiently and in a well-controlled optical mode. In this work, we propose a nanophotonic interface that addresses this challenge using a diamond microdisk coupled to two vertically stacked grating layers. The device is designed to funnel emission from a color center into a nearly Gaussian beam emitted normal to the chip surface. This vertical geometry is especially attractive for scalable quantum memories, since it is compatible with free-space collection and multiplexed architectures. Our design combines strong light-matter interaction with efficient out-coupling. Numerical optimization predicts a Purcell enhancement of about 62, collection efficiency up to 96% for a numerical aperture of 0.7, and mode overlap around 95% with an ideal Gaussian beam. The second grating layer plays an important role: besides improving beam quality, it also makes the device more tolerant to emitter misalignment and dipole-orientation uncertainty. These results suggest that vertically emitting diamond nanophotonic structures could provide an efficient and scalable spin-photon interface for future quantum repeater and quantum memory platforms.► BibTeX data@article{MirzaeiGhormish2026highefficiency, doi = {10.22331/q-2026-03-20-2035}, url = {https://doi.org/10.22331/q-2026-03-20-2035}, title = {High-efficiency vertical emission spin-photon interface for scalable quantum memories}, author = {Mirzaei-Ghormish, Siavash and Bennett, Jeddy and Camacho, Ryan M.}, journal = {{Quantum}}, issn = {2521-327X}, publisher = {{Verein zur F{\"{o}}rderung des Open Access Publizierens in den Quantenwissenschaften}}, volume = {10}, pages = {2035}, month = mar, year = {2026} }► References [1] Kimble, H. J. The quantum internet. Nature. 453, 1023-1030 (2008). https://doi.org/10.1038/nature07127 [2] Gottesman, D., Jennewein, T. & Croke, S. Longer-baseline telescopes using quantum repeaters.
Physical Review Letters. 109, 070503 (2012). https://doi.org/10.1103/PhysRevLett.109.070503 [3] Bersin, E., Sutula, M., Huan, Y., Suleymanzade, A., Assumpcao, D., Wei, Y., Stas, P., Knaut, C., Knall, E., Langrock, C. et al., Telecom networking with a diamond quantum memory. PRX Quantum. 5, 010303 (2024). https://doi.org/10.1103/PRXQuantum.5.010303 [4] Chen, K., Dhara, P., Heuck, M., Lee, Y., Dai, W., Guha, S. & Englund, D. Zero-added-loss entangled-photon multiplexing for ground-and space-based quantum networks.
Physical Review Applied. 19, 054029 (2023). https://doi.org/10.1103/PhysRevApplied.19.054029 [5] Li, L., De Santis, L., Harris, I., Chen, K., Christen, I., Trusheim, M., Han, R. & Englund, D. Heterogeneous integration of spin-photon interfaces with a scalable CMOS platform. CLEO: Fundamental Science. pp. FW3K-2 (2024). https://doi.org/10.1364/CLEO_FS.2024.FW3K.2 [6] Iwasaki, T., Miyamoto, Y., Taniguchi, T., Siyushev, P., Metsch, M., Jelezko, F. & Hatano, M. Tin-vacancy quantum emitters in diamond.
Physical Review Letters. 119, 253601 (2017). https://doi.org/10.1103/PhysRevLett.119.253601 [7] Görlitz, J., Herrmann, D., Thiering, G., Fuchs, P., Gandil, M., Iwasaki, T., Taniguchi, T., Kieschnick, M., Meijer, J., Hatano, M. et al., Spectroscopic investigations of negatively charged tin-vacancy centres in diamond. New Journal of Physics. 22, 013048 (2020). https://doi.org/10.1088/1367-2630/ab6631 [8] Burek, M., Chu, Y., Liddy, M., Patel, P., Rochman, J., Meesala, S., Hong, W., Quan, Q., Lukin, M. & Lončar, M. High quality-factor optical nanocavities in bulk single-crystal diamond. Nature Communications. 5, 5718 (2014). https://doi.org/10.1038/ncomms6718 [9] Wan, N., Mouradian, S. & Englund, D. Two-dimensional photonic crystal slab nanocavities on bulk single-crystal diamond.
Applied Physics Letters. 112, 141102 (2018). https://doi.org/10.1063/1.5021349 [10] Mouradian, S., Wan, N., Schröder, T. & Englund, D. Rectangular photonic crystal nanobeam cavities in bulk diamond.
Applied Physics Letters. 111, 021103 (2017). https://doi.org/10.1063/1.4992118 [11] Saggio, V., Errando-Herranz, C., Gyger, S., Panuski, C., Prabhu, M., De Santis, L., Christen, I., Ornelas-Huerta, D., Raniwala, H., Gerlach, C. et al., Cavity-enhanced single artificial atoms in silicon. Nature Communications. 15, 5296 (2024). https://doi.org/10.1038/s41467-024-49302-0 [12] Hausmann, B., Bulu, I., Venkataraman, V., Deotare, P. & Lončar, M. Diamond nonlinear photonics. Nature Photonics. 8, 369-374 (2014). https://doi.org/10.1038/nphoton.2014.72 [13] Ruf, M., Weaver, M., Dam, S. & Hanson, R. Resonant excitation and Purcell enhancement of coherent nitrogen-vacancy centers coupled to a Fabry–Perot microcavity.
Physical Review Applied. 15, 024049 (2021). https://doi.org/10.1103/PhysRevApplied.15.024049 [14] Janitz, E., Ruf, M., Dimock, M., Bourassa, A., Sankey, J. & Childress, L. Fabry–Perot microcavity for diamond-based photonics. Physical Review A. 92, 043844 (2015). https://doi.org/10.1103/PhysRevA.92.043844 [15] Li, L., Chen, E., Zheng, J., Mouradian, S., Dolde, F., Schröder, T., Karaveli, S., Markham, M., Twitchen, D. & Englund, D. Efficient photon collection from a nitrogen vacancy center in a circular bullseye grating. Nano Letters. 15, 1493-1497 (2015). https://doi.org/10.1021/nl503451j [16] Li, L., Schröder, T., Chen, E., Walsh, M., Bayn, I., Goldstein, J., Gaathon, O., Trusheim, M., Lu, M., Mower, J. et al. Coherent spin control of a nanocavity-enhanced qubit in diamond. Nature Communications. 6, 6173 (2015). https://doi.org/10.1038/ncomms7173 [17] Duan, Y., Chen, K., Englund, D. & Trusheim, M. A vertically-loaded diamond microdisk resonator spin-photon interface. Optics Express. 29, 43082-43090 (2021). https://doi.org/10.1364/OE.442834 [18] Flores, H., Layton, S., Englund, D. & Camacho, R. Alignment-free coupling to arrays of diamond microdisk cavities with fabrication tolerant spin-photon interfaces. Optics Express. 32, 12054-12064 (2024). https://doi.org/10.1364/OE.515620 [19] Claudon, J., Bleuse, J., Malik, N., Bazin, M., Jaffrennou, P., Gregersen, N., Sauvan, C., Lalanne, P. & Gérard, J. A highly efficient single-photon source based on a quantum dot in a photonic nanowire. Nature Photonics. 4, 174-177 (2010). https://doi.org/10.1038/nphoton.2009.287x [20] Reimer, M., Bulgarini, G., Akopian, N., Hocevar, M., Bavinck, M., Verheijen, M., Bakkers, E., Kouwenhoven, L. & Zwiller, V. Bright single-photon sources in bottom-up tailored nanowires. Nature Communications. 3, 737 (2012). https://doi.org/10.1038/ncomms1746 [21] Gschrey, M., Thoma, A., Schnauber, P., Seifried, M., Schmidt, R., Wohlfeil, B., Krüger, L., Schulze, J., Heindel, T., Burger, S. et al., Highly indistinguishable photons from deterministic quantum-dot microlenses utilizing three-dimensional in situ electron-beam lithography. Nature Communications. 6, 7662 (2015). https://doi.org/10.1038/ncomms8662 [22] Wan, N., Shields, B., Kim, D., Mouradian, S., Lienhard, B., Walsh, M., Bakhru, H., Schröder, T. & Englund, D. Efficient extraction of light from a nitrogen-vacancy center in a diamond parabolic reflector. Nano Letters. 18, 2787-2793 (2018). https://doi.org/10.1021/acs.nanolett.7b04684 [23] Zhu, J., Cai, X., Chen, Y. & Yu, S. Theoretical model for angular grating-based integrated optical vortex beam emitters. Optics Letters. 38, 1343 (2013). https://doi.org/10.1364/OL.38.001343Cited byCould not fetch Crossref cited-by data during last attempt 2026-03-20 11:30:43: Could not fetch cited-by data for 10.22331/q-2026-03-20-2035 from Crossref. This is normal if the DOI was registered recently. Could not fetch ADS cited-by data during last attempt 2026-03-20 11:30:43: No response from ADS or unable to decode the received json data when getting the list of citing works.This Paper is published in Quantum under the Creative Commons Attribution 4.0 International (CC BY 4.0) license. Copyright remains with the original copyright holders such as the authors or their institutions.