The realization of quantum networks critically depends on establishing efficient, coherent light-matter interfaces. Optically active spins in diamond have emerged as promising quantum nodes based on their spin-selective optical transitions, long-lived spin ground states, and potential for integration with nanophotonics. Tin-vacancy (SnV
-) centers in diamond are of particular interest because they exhibit narrow-linewidth emission in nanostructures and possess long spin coherence times at temperatures above 1 K. However, a nanophotonic interface for SnV
- centers has not yet been realized. Here, we report cavity enhancement of the emission of SnV
- centers in diamond. We integrate SnV
- centers into one-dimensional photonic crystal resonators and observe a 40-fold increase in emission intensity. The Purcell factor of the coupled system is 25, resulting in channeling of the majority of photons (
90%) into the cavity mode. Our results pave the way for the creation of efficient, scalable spin-photon interfaces based on SnV
- centers in diamond.
Quantum networks rely on the efficient coupling of coherent quantum memories to photonic links. Tin-vacancy centers (SnV) have emerged as promising candidates for the implementation of an optically interfaced quantum memory based on their long spin coherence times at temperatures above 1K. To enhance their interaction with photons SnV centers need to be integrated with high-quality photonic structures. In this work, we report the enhancement of coherent emission of SnV centers by coupling them to a nanophotonic waveguide resonator. We observe strong intensity enhancement of the photon emission when the cavity is resonant with the color center. We demonstrate strong enhancement of the radiative recombination rate of SnV centers resulting in their predominant emission via the coherent zero-phonon line and into the cavity mode. These results are a significant step toward color-center-based quantum information processing applications without the need for dilution refrigerators.
Efficient coupling of optically active qubits to optical cavities is a key challenge for solid-state-based quantum optics experiments and future quantum technologies. Here we present a quantum photonic interface based on a single tin-vacancy center in a micrometer-thin diamond membrane coupled to a tunable open microcavity. We use the full tunability of the microcavity to selectively address individual tin-vacancy centers within the cavity mode volume. Purcell enhancement of the tin-vacancy center optical transition is evidenced both by optical excited state lifetime reduction and by optical linewidth broadening. As the emitter selectively reflects the single-photon component of the incident light, the coupled emitter-cavity system exhibits strong quantum nonlinear behavior. On resonance, we observe a transmission dip of 50% for low incident photon number per Purcell-reduced excited state lifetime, while the dip disappears as the emitter is saturated with higher photon number. Moreover, we demonstrate that the emitter strongly modifies the photon statistics of the transmitted light by observing photon bunching. This work establishes a versatile and tunable platform for advanced quantum optics experiments and proof-of-principle demonstrations on quantum networking with solid-state qubits. Published by the American Physical Society 2024
Efficient coupling between quantum emitters and optical cavities is essential for scalable quantum photonic technologies. Group-IV vacancy centers in diamond, particularly the negatively charged tin-vacancy center, have emerged as promising candidates due to their spectral stability, high Debye-Waller factor, and large orbital splitting in ground states. Here, we demonstrate controlled coupling of a single negatively charged tin-vacancy center hosted in a nanodiamond to a fully tunable Fabry-Pérot microcavity. At cryogenic temperatures, we access the weak-coupling regime and observe a transition from the bad-emitter regime to the bad-cavity regime as the optical transition of the color center narrows. At 4 K, a Purcell factor exceeding 1.7 is measured, confirming cavity-enhanced emission. The obtained results demonstrate the potential of Sn − V − centers in nanodiamonds as a coherent single-photon source for quantum networks.
The negatively charged tin-vacancy center in diamond (SnV
−) is an excellent solid state qubit with optically-addressable transitions and a long electron spin coherence time at elevated (
∼1.7 K). However, implementing scalable quantum nodes with high-fidelity optical readout of the electron spin state requires efficient photon emission and collection from the system. In this manuscript, we report a quantum photonic interface for SnV
− centers based on one-dimensional photonic crystal cavities fabricated in diamond thin films. Furthermore, we provide a rigorous description of the spontaneous emission dynamics of our system, taking into account individual contributions from both the C and D transitions of the emitter. This allows for determination of Purcell factors per transition and, by extension, the C/D branching ratio SnV
− zero phonon line. We observe quality factors up to $\sim$6000 across this sample, and measure up to a 12-fold lifetime reduction, which translates into a Purcell factor of
FC=26.2±1.5 for a targeted C transition. By considering the cavity mode polarization alignment with the C and D transition dipole moments, we validate the C/D branching ratio to be
ηBR=0.75±0.01, in line with previous theoretical and experimental findings.