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, Massachusetts Institute of Technology |
| Citations | 190 |
| Analysis | Full AI Review Included |
6CCVD Technical Briefing: Transform-Limited Quantum Emitters in MPCVD Diamond
Section titled â6CCVD Technical Briefing: Transform-Limited Quantum Emitters in MPCVD DiamondâExecutive Summary
Section titled âExecutive SummaryâThis paper validates the Tin-Vacancy (SnV) center in high-purity Chemical Vapor Deposition (CVD) diamond as a highly promising platform for scalable quantum networks, exhibiting characteristics that significantly surpass other leading Group-IV color centers (SiV, GeV).
- Superior Coherence at High Temperatures: SnV centers achieve long spin coherence times ($T_{2} = 540 \pm 40$ ns) and extended spin lifetimes ($T_{1} > 10$ ms) at accessible liquid-helium temperatures (2.9 K).
- Elimination of Dilution Refrigeration: The high operating temperature (> 1 K) obviates the necessity for complex, expensive dilution refrigeration (< 100 mK) typically required for SiV and GeV centers to suppress phonon-mediated decoherence.
- Transform-Limited Optics: Optical transitions are demonstrated to be lifetime-limited, with minimum measured linewidths of $30 \pm 2$ MHz, confirming the high quality of the spin-photon interface.
- Inversion Symmetry: The inherent crystallographic inversion symmetry limits spectral diffusion and inhomogeneous broadening, crucial for creating identical, stable quantum emitters.
- Engineering Foundation: The research relies on ultra-pure, low-strain diamond substrates (grown by CVD) and subsequent precision nanostructuring (150 nm pillars) to optimize light-matter interaction.
- Core Application: The combination of coherent optical transitions and long spin coherence makes SnV centers ideal candidates for robust quantum optics and scalable quantum networking applications.
Technical Specifications
Section titled âTechnical SpecificationsâThe following critical performance metrics and physical parameters were extracted from the analysis of the SnV quantum emitters in diamond.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Minimum Optical Linewidth (FWHM) | $30 \pm 2$ | MHz | Resonant photoluminescence excitation (PLE) |
| Fluorescence Lifetime ($\tau$) | $4.5 \pm 0.2$ | ns | Pulsed non-resonant excitation (532 nm) |
| Theoretical Transform Limit | $35 \pm 5$ | MHz | Calculated from $(2\pi\tau)^{-1}$ |
| Electron Spin Lifetime ($T_{1}$) | $1.26 \pm 0.28$ | ms | Measured at 4 K (0.13 T magnetic field) |
| Maximum Spin Lifetime ($T_{1}$) | $10.4$ | ms | Achieved upon cooling to 3.25 K |
| Spin Coherence Time ($T_{2}$) | $540 \pm 40$ | ns | Measured via ODMR at 2.9 K |
| Operating Temperature (Minimum) | 2.9 | K | Temperature where $T_{2}$ reaches 13C nuclear spin-bath limit |
| SnV Nanostructure Geometry | R = 150 | nm | Nanofabricated diamond pillars |
| Ground State Splitting | $\sim 850$ | GHz | Primarily due to spin-orbit coupling (99%) |
| Magnetic Field Range | 0.13 to 9 | T | Used for magneto-optical and spin spectroscopy |
Key Methodologies
Section titled âKey MethodologiesâThe following is an ordered summary of the key experimental steps and recipe parameters used to generate and characterize the highly coherent SnV centers.
- Substrate Material: Ultra-pure diamond wafers grown by Chemical Vapor Deposition (CVD) were utilized as the starting material to ensure minimal intrinsic defects and low background strain.
- Defect Generation: Sn-Vacancy (SnV) centers were created through Sn ion implantation, a standard technique for introducing Group-IV color centers into the diamond lattice.
- Structural Modification: Wafers were nanofabricated into diamond pillars (radius $R = 150$ nm) to create optical photonic structures, crucial for enhanced light collection and future integration.
- Cryogenic Environment: Measurements were performed using a cryogenic setup capable of temperatures in the liquid helium regime (down to 2.9 K) to mitigate phonon scattering effects.
- Optical Characterization: Spectroscopy was performed using both non-resonant (532 nm) and highly stable, narrowband resonant laser excitation.
- Spin Initialization and Readout: Spin-selective resonant excitation was employed, demonstrating the ability to optically initialize the spin state with high purity (98% initialization achieved at 4 K).
- Coherence Measurement: Optically Detected Magnetic Resonance (ODMR) was implemented by applying a resonant microwave pulse between optical initialization and readout pulses, allowing determination of the spin coherence time ($T_{2}$) across various temperatures.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & Capabilitiesâ6CCVD is uniquely positioned to supply the advanced diamond materials required to replicate, extend, and scale the groundbreaking research demonstrated using SnV centers for quantum networking. Our MPCVD growth process is designed to deliver the ultra-high purity, low-strain material foundation essential for coherent quantum applications.
Applicable Materials
Section titled âApplicable MaterialsâThe success of SnV centers relies directly on the purity and crystallographic perfection of the substrate diamond. We recommend the following material solution:
- Optical Grade Single Crystal Diamond (SCD): This material is crucial for minimizing nitrogen impurities (which limit $T_{1}$ and $T_{2}$) and reducing intrinsic strain, ensuring the high spectral stability and transform-limited linewidths reported.
- Key Advantage: Our SCD wafers are optimized for low defect density, providing an ideal, homogeneous host lattice for subsequent ion implantation of Sn.
Customization Potential
Section titled âCustomization PotentialâReplicating and scaling this quantum research requires precision engineering services, especially concerning geometry and surface quality, both of which 6CCVD excels in providing:
| Requirement from Research | 6CCVD Capability | Value Proposition |
|---|---|---|
| Substrate Preparation | Polishing Ra < 1 nm (SCD) | Ensures atomically flat surface necessary for high-fidelity nanofabrication (e.g., electron beam lithography for 150 nm pillars). |
| Custom Wafer Dimensions | Wafers up to 125 mm (PCD/SCD) | Facilitates scaling from research-scale coupons to larger, integrated quantum chip fabrication runs. |
| Thickness Control | SCD thickness range: 0.1 ”m - 500 ”m | Provides tailored material thickness specific to photonic device requirements (e.g., precise membranes for device integration). |
| Integrated Microwave Control | Custom Metalization Services (Au, Pt, Ti, W) | Enables the fabrication of integrated microwave striplines directly on the diamond surface, required for efficient application of the high magnetic fields (up to 9 T) and ODMR measurements used in this study. |
| Geometrical Flexibility | Precision Laser Cutting and Dicing | Allows researchers to receive custom-shaped coupons or precisely separated devices ready for implantation and subsequent etching/nanofabrication. |
Engineering Support
Section titled âEngineering Supportâ6CCVDâs in-house PhD material science team understands the critical interplay between CVD growth parameters and quantum defect performance. We provide dedicated consultation services to optimize starting material specifications for ion implantation and subsequent photonic device processing. Our expertise in controlling nitrogen and compensating boron levels is vital for maximizing spin coherence in Group-IV color center projects.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
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.