Transform-Limited Photons From a Coherent Tin-Vacancy Spin in Diamond
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2020-01-14 |
| Journal | Physical Review Letters |
| Authors | Matthew E. Trusheim, Benjamin Pingault, Noel Wan, Mustafa GĂŒndoÄan, Lorenzo De Santis |
| Institutions | University of Oxford, University of Cambridge |
| Citations | 190 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThe research demonstrates the Tin-Vacancy (SnV) center in diamond as a highly viable, scalable spin-photon interface for quantum technologies, overcoming the severe cryogenic limitations of previous Group-IV centers (SiV, GeV).
- Transform-Limited Optics: SnV optical transitions in nanofabricated pillars exhibit linewidths as low as 30 ± 2 MHz, consistent with the radiative lifetime limit (4.5 ns), confirming high optical quality essential for quantum interfaces.
- High-Temperature Coherence: The SnV achieves long spin coherence (T2 = 540 ± 40 ns) and spin lifetime (T1 > 10 ms) at accessible liquid-helium temperatures (2.9 K to 4 K).
- Feasibility Advantage: This performance eliminates the requirement for complex and costly dilution refrigeration (typically < 100 mK) necessary for SiV and GeV centers, significantly improving the feasibility of SnV-based quantum networks.
- Phonon Suppression: The large ground-state orbital splitting of the SnV effectively suppresses single-phonon scattering, which is the dominant spin dephasing mechanism in SiV and GeV at these temperatures.
- Spin Initialization: Optical initialization and readout of the electronic spin were demonstrated, achieving 98% spin polarization at 4 K.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Optical Transition Linewidth (Best) | 30 ± 2 | MHz | Measured via PLE, consistent with transform limit. |
| Optical Transition Linewidth (Mean) | 57 ± 17 | MHz | Measured across several single SnV centers. |
| Fluorescence Lifetime (Ï) | 4.5 ± 0.2 | ns | Measured after pulsed non-resonant excitation. |
| Spin Lifetime (T1) (Max) | 10.4 | ms | Achieved upon cooling to 3.25 K (phonon-limited). |
| Spin Coherence Time (T2) (Max) | 540 ± 40 | ns | Achieved at 2.9 K (limited by 13C nuclear spin bath). |
| Spin Polarization | 98 | % | Achieved at 4 K under resonant pumping. |
| Ground State Splitting (ÎEg) | ~850 | GHz | Primarily due to spin-orbit coupling (99%). |
| Excited State Splitting (ÎEe) | ~3000 | GHz | Due to spin-orbit coupling (80%) and Jahn-Teller effect. |
| Operating Temperature Range | 2.9 to 6 | K | Liquid-helium temperatures (avoids dilution refrigeration). |
| Nanopillar Radius (R) | 150 | nm | Nanofabricated structures used for single-emitter studies. |
| Magnetic Field (B) | 0.13 to 9 | T | Used for spin initialization and spectroscopy. |
Key Methodologies
Section titled âKey MethodologiesâThe SnV centers were created and characterized using a combination of advanced material processing and cryogenic optical techniques:
- Material Growth: Ultra-pure diamond substrates were grown using Chemical Vapor Deposition (CVD).
- SnV Creation: Single SnV centers were created through Sn implantation into the diamond substrate.
- Nanostructure Fabrication: The diamond was nanofabricated into pillars (radius R = 150 nm) to enhance photon collection efficiency.
- Electronic Structure Determination: Cryogenic magneto-optical spectroscopy was performed under varying magnetic fields (up to 9 T) to verify the inversion-symmetric electronic structure and determine energy level splittings.
- Optical Coherence Measurement: Photoluminescence Excitation (PLE) spectroscopy was used with a narrowband laser to measure the transition linewidths, confirming transform-limited emission.
- Spin Initialization and Readout: Spin-selective resonant excitation was implemented under an external magnetic field (0.13 T) to optically initialize and read out the electronic spin state.
- Spin Dynamics Characterization:
- Spin lifetime (T1) was measured using time-resolved fluorescence decay, showing exponential temperature scaling consistent with single phonon-mediated decay.
- Spin coherence time (T2) was measured using Optically Detected Magnetic Resonance (ODMR) at temperatures down to 2.9 K.
Commercial Applications
Section titled âCommercial ApplicationsâThe demonstrated properties of the SnV centerâcombining transform-limited optics with long spin coherence at accessible temperaturesâmake it a critical component for next-generation quantum technologies:
- Quantum Networks and Repeaters: SnV centers serve as robust stationary matter qubits that can be efficiently coupled to flying photonic qubits, enabling long-distance quantum communication.
- Scalable Quantum Computing: The ability to operate the spin-photon interface at liquid-helium temperatures (instead of millikelvin) drastically reduces the complexity and cost of quantum computing hardware.
- Quantum Sensing: Utilizing the long spin coherence time (T2) for high-sensitivity magnetic or electric field sensing applications.
- Integrated Quantum Photonics: The SnVâs integration into nanofabricated diamond structures (nanopillars) facilitates the development of on-chip quantum photonic circuits for enhanced light-matter interaction.
- Advanced Diamond Material Supply: Requires and drives the development of ultra-pure, high-quality CVD diamond substrates suitable for precise ion implantation and subsequent nanofabrication.
View Original Abstract
Solid-state quantum emitters that couple coherent optical transitions to long-lived spin qubits are essential for quantum networks. Here we report on the spin and optical properties of individual tin-vacancy (SnV) centers in diamond nanostructures. Through cryogenic magneto-optical and spin spectroscopy, we verify the inversion-symmetric electronic structure of the SnV, identify spin-conserving and spin-flipping transitions, characterize transition linewidths, measure electron spin lifetimes and evaluate the spin dephasing time. We find that the optical transitions are consistent with the radiative lifetime limit even in nanofabricated structures. The spin lifetime is phononlimited with an exponential temperature scaling leading to $T_1$ $>$ 10 ms, and the coherence time, $T_2$ reaches the nuclear spin-bath limit upon cooling to 2.9 K. These spin properties exceed those of other inversion-symmetric color centers for which similar values require millikelvin temperatures. With a combination of coherent optical transitions and long spin coherence without dilution refrigeration, the SnV is a promising candidate for feasable and scalable quantum networking applications.