Tin-Vacancy Centers in Diamond for Quantum Network

At a Glance

Metadata	Details
Publication Date	2021-01-01
Journal	The Review of Laser Engineering
Authors	Takayuki Iwasaki
Institutions	Tokyo Institute of Technology
Analysis	Full AI Review Included

Technical Documentation: SnV Centers in Diamond for Quantum Networks

This document analyzes the research on Tin-Vacancy (SnV) centers in diamond, highlighting the material requirements necessary to advance this promising quantum emitter technology. 6CCVD specializes in providing the high-purity, isotopically enriched, and custom-dimensioned MPCVD diamond required for successful replication and extension of this research.

Executive Summary

The research confirms the potential of SnV centers as superior quantum emitters for quantum network applications, overcoming limitations found in SiV and GeV centers.

Superior Emitter: SnV centers exhibit a sharp Zero Phonon Line (ZPL) at 619 nm and high fluorescence intensity, making them excellent single-photon sources.
Enhanced Spin Properties: The SnV center possesses a large ground state splitting ($\Delta G_S$) of approximately 850 GHz, significantly higher than SiV/GeV, which is crucial for suppressing phonon-induced decoherence at Kelvin temperatures.
Coherence Achievement: Initial spin dephasing time (T₂*) of 540 ns was measured at 2.9 K, demonstrating superior performance compared to other Group-IV centers at similar temperatures.
Material Criticality: Achieving long spin coherence times (T₂) requires the use of isotopically enriched ¹²C diamond to minimize interaction with ¹³C nuclear spins.
Processing Requirement: High-quality SnV formation necessitates extreme thermal stability, requiring annealing temperatures of 2000 °C or higher.
Future Development: Success hinges on advanced spin control techniques (CPMG, XY8) and precise control over multiple emitters (wavelength tuning via strain/devices) to achieve Hong-Ou-Mandel (HOM) interference.

Technical Specifications

Parameter	Value	Unit	Context
Zero Phonon Line (ZPL) Wavelength	619	nm	Room temperature Photoluminescence (PL) spectrum
Required Annealing Temperature	> 2000	°C	Necessary for high-quality SnV center formation
Ground State Splitting ($\Delta G_S$)	~850	GHz	Determined via low-temperature PL fine structure
Fourier-Limited Linewidth	~18	MHz	Derived from excited state lifetime
Initial Spin Dephasing Time (T₂*)	540	ns	Measured using CW-ODMR at 2.9 K
Target Spin Coherence Time (T₂)	Microseconds to Milliseconds	N/A	Goal for robust quantum memory applications
Required ¹³C Concentration	Low (Isotopically Enriched)	%	To suppress nuclear spin decoherence effects

Key Methodologies

The research relies on advanced material synthesis and precise quantum measurement techniques:

SnV Center Creation: Sn atoms are introduced into the diamond lattice, followed by high-temperature annealing (2000 °C or higher) to form high-quality SnV centers with D_3d symmetry.
Optical Characterization: Photoluminescence (PL) spectroscopy is used to confirm the ZPL at 619 nm and low-temperature PL is used to measure the fine structure and determine the large ground state splitting ($\Delta G_S$).
Spin Measurement: Continuous Wave Optically Detected Magnetic Resonance (CW-ODMR) is employed to measure the initial spin dephasing time (T₂*).
Coherence Extension (Proposed): Pulsed microwave sequences, including Hahn Echo, Carr-Purcell-Meiboom-Gill (CPMG), and XY8 dynamic decoupling sequences, are proposed to extend the spin coherence time (T₂).
Wavelength Control: Techniques such as applying strain (via nanostructures or devices) or utilizing p-n junction structures are necessary to precisely tune and match the emission wavelength of separated SnV centers.
Quantum Interference Testing: Hong-Ou-Mandel (HOM) interference experiments are required to verify the indistinguishability of photons emitted from spatially separated, identical SnV quantum emitters.

6CCVD Solutions & Capabilities

6CCVD provides the specialized MPCVD diamond materials and processing services essential for replicating and advancing SnV quantum emitter research, particularly focusing on material purity, thermal stability, and device integration.

Applicable Materials

To achieve the long spin coherence times (T₂) required for quantum networks, the material must minimize decoherence sources.

Material Specification	6CCVD Offering	Application Context
Isotopically Enriched Single Crystal Diamond (SCD)	Ultra-high purity SCD with < 0.1% ¹³C concentration.	Essential for suppressing electron spin interaction with ¹³C nuclear spins, enabling T₂ extension via dynamic decoupling sequences (CPMG/XY8).
High-Purity SCD Substrates	SCD substrates up to 10 mm thick, capable of withstanding extreme processing.	Required for supporting thin films during the critical high-temperature annealing step (> 2000 °C) necessary for SnV formation.
Optical Grade SCD Thin Films	SCD layers from 0.1 µm to 500 µm thick, polished to Ra < 1 nm.	Provides the low-defect host material necessary for high-fluorescence, Fourier-limited linewidth SnV centers, and facilitates nanophotonic device fabrication.

Customization Potential

The research explicitly calls for advanced device structures (e.g., p-n junctions) and nanostructure integration for strain control and wavelength tuning. 6CCVD offers comprehensive customization capabilities to meet these engineering demands.

Research Requirement	6CCVD Customization Service	Technical Benefit
Device Integration & Electrical Contacts	Custom Metalization: Deposition of Au, Pt, Pd, Ti, W, or Cu layers.	Enables reliable electrical injection, readout, and the fabrication of p-n junction devices for wavelength tuning and advanced control.
Nanostructure Fabrication	Ultra-Low Roughness Polishing: Ra < 1 nm (SCD) and Ra < 5 nm (PCD).	Ensures optimal surface quality for lithography, etching, and the creation of high-Q nanophotonic cavities and waveguides.
Unique Dimensions	Custom Dimensions: Plates/wafers up to 125 mm (PCD) or custom-cut SCD.	Supports scaling from fundamental research to integrated quantum circuits and large-scale device arrays.
Strain Engineering	Precision Thickness Control: SCD films grown to exact specifications (e.g., 5 µm ± 0.1 µm).	Critical for controlled strain application, which is necessary to match the ZPL wavelength of separated SnV emitters for HOM interference.

Engineering Support

6CCVD’s in-house team of PhD material scientists and engineers are experts in MPCVD growth parameters, defect engineering, and post-processing stability.

Material Selection Consultation: Our team assists researchers in selecting the optimal diamond grade (e.g., isotopic purity, nitrogen concentration) to maximize SnV yield and coherence time for specific Quantum Emitter and Quantum Network projects.
Thermal Stability Analysis: We provide technical guidance on the thermal budget and material stability required for high-temperature annealing processes (> 2000 °C) without compromising the diamond substrate or thin film interface.
Integration Expertise: Support is available for optimizing metalization recipes and surface preparation techniques crucial for creating robust electrical and photonic interfaces.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

Quantum emitters in diamond are a promising candidate for quantum network applications. Here, we show basic properties of tin-vacancy (SnV) centers in diamond, which we recently discovered. The SnV center shows a sharp zero phonon line and a high fluorescence intensity. The SnV center has a possibility to have a long spin coherence time in the Kelvin temperature range, in contrast to other group-IV color centers, i.e. silicon-vacancy and germanium-vacancy centers. We discuss important experiments regarding spin and optical properties of the SnV quantum emitter for further development towards quantum network.

Tech Support

Original Source

DOI: https://doi.org/10.2184/lsj.49.6_317