Above-Unity Coherent Cooperativity of Tin-Vacancy Centers in Diamond Photonic Crystal Cavities

Journal Article (2026)
Author(s)

Nina Codreanu (TU Delft - BUS/Quantum Delft, Kavli institute of nanoscience Delft, TU Delft - QuTech Advanced Research Centre)

Tim Turan (Kavli institute of nanoscience Delft, TU Delft - QID/Hanson Lab, TU Delft - QuTech Advanced Research Centre)

Daniel Bedialauneta Rodriguez (TU Delft - QuTech Advanced Research Centre, TU Delft - QID/Hanson Lab, Kavli institute of nanoscience Delft)

Matteo Pasini (TU Delft - QuTech Advanced Research Centre, Kavli institute of nanoscience Delft, TU Delft - QID/Hanson Lab)

Lorenzo de Santis (TU Delft - QID/Hanson Lab, Kavli institute of nanoscience Delft, TU Delft - QuTech Advanced Research Centre)

Maximilian Ruf (Kavli institute of nanoscience Delft, TU Delft - QuTech Advanced Research Centre, TU Delft - QID/Hanson Lab)

Christian F. Primavera (TU Delft - QuTech Advanced Research Centre, TU Delft - QID/Hanson Lab, Kavli institute of nanoscience Delft)

Leonardo G.C. Wienhoven (TU Delft - QuTech Advanced Research Centre, TU Delft - QID/Hanson Lab, Kavli institute of nanoscience Delft)

Caroline E. Smulders (TU Delft - QuTech Advanced Research Centre, Kavli institute of nanoscience Delft, TU Delft - BUS/Quantum Delft)

Simon Gröblacher (Kavli institute of nanoscience Delft, TU Delft - Applied Sciences)

Ronald Hanson (Kavli institute of nanoscience Delft, TU Delft - QID/Hanson Lab, TU Delft - Applied Sciences, TU Delft - QuTech Advanced Research Centre)

Research Group
BUS/Quantum Delft
DOI related publication
https://doi.org/10.1103/z514-v4n6 Final published version
More Info
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Publication Year
2026
Language
English
Research Group
BUS/Quantum Delft
Journal title
Physical Review X
Issue number
2
Volume number
16
Article number
021060
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3
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Abstract

The tin-vacancy center in diamond (SnV) has emerged as a compelling building block for realizing next-generation quantum networks thanks to its excellent optical and spin properties. Coupling to photonic crystal cavities (PCCs) promises to further enhance the SnV light-matter interface and unlock a diverse range of entanglement generation protocols. Recent pioneering experiments showing Purcell enhancement of SnV centers in PCCs underscore this potential. However, optical coupling that is coherent—the key ingredient for use in quantum protocols—has so far remained elusive. Here, we demonstrate above-unity coherent cooperativity of SnV centers embedded in photonic crystal cavities. We fabricate freestanding PCCs using a quasi-isotropic undercut. Across two samples, we conduct room-temperature characterizations, measuring resonances for 327 cavities, with an average quality factor exceeding Q = 1.1(4)× 104. Two cavity-coupled emitters are examined in detail, exhibiting quality factors up to Q = 25.4(4)× 103 and Purcell-reduced lifetimes corresponding to cooperativities up to C = 20.3(11). Furthermore, the single SnVs are observed to strongly modulate the cavity transmission with an extinction contrast up to 98.8(4) on resonance. Finally, SnV linewidth measurements reveal above-unity coherent cooperativities in both devices, with the highest value being C_coh = 8.3(12). These results open the door to using cavity-coupled SnV centers as efficient, coherent light-matter interfaces for future quantum networks.