Optically detected flip-flops between different spin ensembles in diamond

At a Glance

Metadata	Details
Publication Date	2021-04-30
Journal	Physical review. B./Physical review. B
Authors	Sergei Masis, Sergey Hazanov, Nir Alfasi, Oleg Shtempluck, Eyal Buks
Institutions	Technion – Israel Institute of Technology
Analysis	Full AI Review Included

Technical Documentation & Analysis: Optically Detected Spin Dynamics in Diamond

This documentation analyzes the requirements and findings of the research paper “Optically detected flip-flops between different spin ensembles in diamond” and maps them directly to the advanced material capabilities offered by 6ccvd.com.

Executive Summary

Core Achievement: Demonstrated direct, stimulated spin flip-flop interaction between different Nitrogen-Vacancy (NV^-) ensembles and between NV^- and Substitutional Nitrogen (P1) defects in diamond using Optically Detected Magnetic Resonance (ODMR).
Material Basis: The experiment relied on high-density NV^- centers (3.25 x 10¹⁷ cm^-3) created via 2.8 MeV electron irradiation and annealing of Type Ib HPHT single crystal diamond.
Key Findings for Quantum Sensing: The study provides crucial insight into dipolar coupling and cross-polarization dynamics, which are essential for optimizing Dynamic Nuclear Polarization (DNP) and improving the sensitivity of diamond-based detectors and masers.
Acoustic Coupling: Observed modulation patterns attributed to strain coupling between NV centers and bulk acoustic standing waves in the 0.5 mm thick diamond wafer, relevant for integrated quantum acoustic devices.
6CCVD Value Proposition: 6CCVD specializes in providing the high-purity, custom-oriented, and precisely processed Single Crystal Diamond (SCD) wafers necessary to replicate, control, and extend this spin-ensemble engineering research.
Customization Focus: We offer custom SCD plates with specific nitrogen doping levels, precise (110) orientation, ultra-low roughness polishing (Ra < 1 nm), and integrated metalization for optimized MW coupling structures.

Technical Specifications

The following hard data points were extracted from the experimental methodology and results:

Parameter	Value	Unit	Context
Diamond Type (Starting)	Type Ib HPHT Single Crystal	N/A	Used for high NV density creation
Wafer Orientation	(110)	N/A	Surface plane, critical for NV alignment
Wafer Thickness ($t$)	0.5	mm	Used in acoustic wave calculations
Initial Nitrogen Concentration	< 200	ppm	Before irradiation/annealing
Electron Irradiation Dose	8 x 10¹⁸	e/cm²	Used 2.8 MeV electrons
Annealing Temperature	900	°C	Used to form NV centers
Resulting NV^- Concentration ($n_{s}$)	3.25 x 10¹⁷	cm^-3	Measured fluorescent count
NV^-:P1 Ratio (Estimated)	1:3	N/A	Based on Electron Spin Resonance (ESR) data
Zero Field Splitting ($D_{NV}$)	2π x 2.87	GHz	NV^- ground state splitting
Experimental Temperature	3.5	K	Cryogenic measurement conditions
Excitation Wavelength	637	nm	Red laser, near NV-Zero-Phonon Line (ZPL)
Acoustic Beating Frequency ($f_{a}$)	20.4	MHz	Attributed to bulk acoustic standing waves

Key Methodologies

The experiment relied on precise material engineering and a specialized ODMR setup:

Material Selection: Use of Type Ib HPHT single crystal diamond with a (110) surface orientation, chosen for its high initial nitrogen content (< 200 ppm).
NV Creation Protocol: The wafer was irradiated with 2.8 MeV electrons at a high dose (8 x 10¹⁸ e/cm²) to create vacancies, followed by high-temperature annealing (900 °C for 2 hours) to mobilize vacancies and form NV centers.
Surface Preparation: The diamond was acid boiled in a mixture of Perchloric, Sulfuric, and Fuming Nitric acids to ensure a clean surface, essential for high-contrast optical measurements.
Setup Integration: The diamond wafer was glued to a sapphire substrate carrying a superconducting spiral resonator (though the resonator was bypassed for the reported measurements).
Cryogenic ODMR: Measurements were performed at 3.5 K using a superconducting solenoid (main coil) and two smaller superconducting coils (side coils) to control the magnetic field ($B$).
Optical Excitation: A 637 nm red laser was used to excite the NV centers near the ZPL, and Photoluminescence (PL) was collected via a multi-mode optical fiber positioned normal to the diamond face.
MW/RF Delivery: Radio frequency radiation was introduced via a flexible coaxial cable terminated with a MW loop antenna pressed against the (110) diamond face for efficient spin manipulation.
Detection: The PL signal was detected by a reverse-biased photo-diode (PD) and demodulated using a lock-in amplifier synchronized to the 151 Hz amplitude modulation of the MW signal, maximizing sensitivity.

6CCVD Solutions & Capabilities

This research highlights the critical need for highly controlled, custom-engineered diamond materials. 6CCVD’s MPCVD capabilities are perfectly suited to meet and exceed these requirements, enabling researchers to optimize spin ensemble dynamics for next-generation quantum technologies.

Research Requirement/Challenge	6CCVD Solution & Capability	Technical Advantage
High NV Density & P1 Control	Nitrogen-Doped Single Crystal Diamond (SCD)	We offer SCD grown with controlled nitrogen incorporation, allowing precise tuning of the initial P1 concentration, which is crucial for subsequent NV creation via irradiation/annealing protocols.
Specific Crystal Orientation	Custom (110) and (100) SCD Wafers	The experiment required a (110) surface to align NV axes effectively. 6CCVD supplies SCD wafers in standard (100) or custom (110) orientations, ensuring optimal alignment with external magnetic fields.
Custom Dimensions & Thickness	SCD Plates up to 500 µm; Substrates up to 10 mm	The paper used a 0.5 mm thick wafer. We provide custom thickness control for SCD (0.1 µm - 500 µm) and thicker substrates (up to 10 mm), accommodating specific acoustic or thermal requirements.
High-Quality Optical Interface	Ultra-Low Roughness Polishing	We guarantee SCD polishing to Ra < 1 nm. This minimizes surface scattering and defects, which is vital for high-contrast ODMR and maintaining long spin coherence times.
Efficient MW Coupling	Integrated Custom Metalization	The paper used an external loop antenna. 6CCVD offers in-house deposition of Au, Pt, Ti, W, and Cu to fabricate integrated microwave structures (e.g., coplanar waveguides or striplines) directly on the diamond surface, significantly improving MW field homogeneity and coupling efficiency at 3.5 K.
Scalability and Uniformity	Large-Area Polycrystalline Diamond (PCD)	For scaling up detector arrays or maser applications, we offer PCD plates up to 125 mm diameter, polished to Ra < 5 nm, providing a cost-effective platform for high-volume spin ensemble experiments.

Applicable Materials

To replicate or extend this research, we recommend the following 6CCVD materials:

Optical Grade SCD: For experiments requiring the lowest possible strain and highest coherence, suitable for low-density NV studies or high-fidelity quantum operations.
Nitrogen-Doped SCD: Specifically engineered for high-density NV creation via post-growth irradiation and annealing, matching the material requirements of this paper for spin ensemble studies and hyperpolarization protocols.

Engineering Support

6CCVD’s in-house PhD team specializes in diamond material science and quantum applications. We can assist researchers with:

Optimizing material selection (SCD vs. PCD, doping levels) for specific ODMR/ELDOR protocols.
Designing custom spin bath engineering solutions to control decoherence and enhance cross-polarization efficiency.
Developing specifications for integrated microwave delivery structures and custom metalization stacks (e.g., Ti/Pt/Au).

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

View Original Abstract

We employ the technique of optical detection of magnetic resonance to study\ndipolar interaction in diamond between nitrogen-vacancy color centers of\ndifferent crystallographic orientations and substitutional nitrogen defects. We\ndemonstrate optical measurements of resonant spin flips-flips (second Larmor\nline), and flip-flops between different spin ensembles in diamond. In addition,\nthe strain coupling between the nitrogen-vacancy color centers and bulk\nacoustic modes is studied using optical detection. Our findings may help\noptimizing cross polarization protocols, which, in turn, may allow improving\nthe sensitivity of diamond-based detectors.\n

Tech Support

Original Source

DOI: https://doi.org/10.1103/physrevb.103.165203