Hyperfine-enhanced gyromagnetic ratio of a nuclear spin in diamond

At a Glance

Metadata	Details
Publication Date	2016-08-03
Journal	New Journal of Physics
Authors	S Sangtawesin, C A McLellan, B. A. Myers, A. C. Bleszynski Jayich, D. D. Awschalom
Citations	27
Analysis	Full AI Review Included

Technical Documentation & Analysis: Hyperfine-Enhanced Gyromagnetic Ratio of a Nuclear Spin in Diamond

This document analyzes the research paper “Hyperfine-Enhanced Gyromagnetic Ratio of a Nuclear Spin in Diamond” to highlight the critical material requirements and demonstrate how 6CCVD’s advanced MPCVD diamond solutions meet and exceed the needs for replicating and advancing this quantum technology.

Executive Summary

This research successfully demonstrates a path toward rapid, direct control of nuclear spins in diamond NV centers, a crucial step for scalable solid-state quantum computing.

Core Achievement: Demonstrated a tunable, hyperfine-mediated enhancement of the effective nuclear gyromagnetic ratio ($\gamma_{N,eff}$) by a factor up to 57.
Quantum Control: The enhancement reduces the required RF power and enables full nuclear spin Rabi oscillations on a few microsecond timescale, significantly faster than typical bare nuclear spin control (10-50 µs).
Material Requirement: The experiment relies on high-purity, low-strain Type-IIa diamond (Single Crystal Diamond, SCD) to isolate the intrinsic $^{14}$N NV center system.
Mechanism: The enhancement is achieved by coupling the $^{14}$N nuclear spin to the NV electronic spin, tunable by varying the external DC magnetic field (B_z).
6CCVD Value Proposition: 6CCVD provides the necessary ultra-high purity SCD substrates, custom dimensions, and integrated metalization services required to fabricate the stripline structures essential for delivering MW and RF pulses.

Technical Specifications

The following hard data points were extracted from the experimental results, focusing on parameters critical for material selection and device performance.

Parameter	Value	Unit	Context
Maximum Enhancement Factor ($\gamma_{N,eff}/\gamma_{N}$)	57	Dimensionless	Achieved at B_z = 873 G
DC Magnetic Field (B_z) Range	514 to 873	G	Used for tuning the enhancement
Nuclear Spin Polarization (P)	> 95	%	Achieved near the ESLAC (B_z = 514 G)
Required RF Power (Sample)	~10	mW	Needed for full nuclear spin Rabi oscillation
Enhanced Nuclear Spin Rabi Period	Few	µs	Allows for rapid quantum control
Bare Nuclear Gyromagnetic Ratio ($\gamma_{N}$)	0.308	kHz/G	Intrinsic $^{14}$N value
NV Zero-Field Splitting (D)	2.87	GHz	Fundamental NV property
Excitation Wavelength	532	nm	Used for optical initialization and readout
Surface Roughness (Implied)	Ra < 5	nm	Required for high-fidelity stripline fabrication

Key Methodologies

The experiment utilized a combination of high-purity diamond material, precise magnetic field control, and advanced microwave/RF pulse delivery techniques.

Material Selection: A naturally occurring NV center was selected from a high-purity type-IIa diamond sample (Element Six). High purity is essential to minimize decoherence from background impurities (e.g., $^{13}$C).
Optical Setup: A confocal microscope was used, employing a 532 nm laser for optical initialization and readout (Photoluminescence, PL). A high numerical aperture (NA = 0.95) objective was used for collection.
RF/MW Delivery: Quantum control was achieved by applying Microwave (MW) and Radio Frequency (RF) pulses through a short-terminated stripline fabricated directly on the diamond surface.
Signal Generation: Two signal generators (SRS SG394 and Agilent N5181A) were used to generate MW and RF signals, combined via a resistive splitter-combiner, and amplified (Triad RF TA1003).
Initialization & Readout: The system was polarized by working close to the Excited State Level Anti-Crossing (ESLAC, B_z ~ 500 G). A selective MW $\pi$-pulse was used to map the nuclear spin state to the electronic spin state for optical readout.
Measurement: Nuclear spin Rabi oscillations were measured by plotting PL intensity as a function of the RF pulse duration ($T_{RF}$). The Rabi frequency ($\Omega_{N}$) was then plotted against the RF magnetic field ($B_{RF}$) to determine the effective gyromagnetic ratio ($\gamma_{N,eff}$).

6CCVD Solutions & Capabilities

6CCVD is uniquely positioned to supply the foundational materials and custom engineering required to replicate and extend this high-impact research in quantum control.

Applicable Materials

To achieve the high coherence and low decoherence rates necessary for NV center quantum control, the highest purity diamond is mandatory.

Material Requirement	6CCVD Solution	Technical Specification	Relevance to Research
High Purity Substrate	Optical Grade SCD	Nitrogen concentration < 1 ppb (Type IIa equivalent)	Minimizes background spin noise and maximizes coherence time ($T_2$).
Custom Thickness	SCD Plates	0.1 µm to 500 µm	Allows precise control over NV depth and integration with surface structures (striplines).
Surface Quality	Polished SCD	Ra < 1 nm	Essential for high-fidelity lithography and fabrication of the on-chip stripline structure.
Doping (Future Extension)	Boron-Doped (BDD)	SCD or PCD up to 10²¹ cm^-3	For future integration of NV centers with superconducting circuits or electrochemical sensing.

Customization Potential

The experimental setup relies on a stripline fabricated on the diamond surface to deliver high-power MW/RF pulses. 6CCVD offers integrated services to streamline device fabrication.

Custom Metalization: The stripline requires precise metal contacts. 6CCVD offers in-house metalization capabilities, including standard stacks like Ti/Pt/Au, W, or Cu, tailored to the specific impedance and power handling requirements of the RF/MW circuitry.
Custom Dimensions: While the paper used a small sample, 6CCVD can supply SCD plates up to 10mm thick and PCD wafers up to 125mm in diameter, allowing for scaling up the experimental platform or integrating multiple devices on a single substrate.
Precision Fabrication: We offer laser cutting and dicing services to provide custom geometries and precise alignment features necessary for integrating the diamond substrate into complex cryo-optical setups.

Engineering Support

The successful replication of this work requires careful material selection to ensure low strain and minimal background impurities.

NV Center Optimization: 6CCVD’s in-house PhD team specializes in optimizing MPCVD growth parameters to produce diamond with the specific purity and crystalline quality required for NV center quantum sensing and quantum memory projects.
Material Consultation: We provide expert consultation on selecting the optimal substrate thickness and surface termination (e.g., H-terminated vs. O-terminated) to maximize the performance and stability of surface-fabricated devices like the required striplines.
Global Logistics: We ensure reliable, global shipping (DDU default, DDP available) to deliver sensitive, high-value diamond materials directly to research facilities worldwide.

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

View Original Abstract

Nuclear spins in the solid state environment of diamond are highly coherent,\nbut difficult to rapidly control due to the small nuclear gyromagnetic ratio.\nHere we demonstrate a more than 50-fold enhancement of the effective nuclear\ngyromagnetic ratio by coupling the nuclear spin to an electronic spin of a\nnitrogen-vacancy (NV) center in diamond. The enhancement allows for faster\nnuclear spin rotations and is in good agreement with second-order perturbation\ntheory. The method may be applied to other systems with similar\nelectron-nuclear spin interactions, such as phosphorous donors in silicon,\nopening up the possibility of fast and direct nuclear spin control in coupled\nspin systems.\n

Tech Support

Original Source

DOI: https://doi.org/10.1088/1367-2630/18/8/083016