A quantum radio frequency signal analyzer based on nitrogen vacancy centers in diamond

At a Glance

Metadata	Details
Publication Date	2022-07-27
Journal	Communications Engineering
Authors	Simone Magaletti, Ludovic Mayer, Jean-François Roch, Thierry Debuisschert
Institutions	Thales (France), Laboratoire Lumière, Matière et Interfaces
Citations	31
Analysis	Full AI Review Included

Quantum Diamond Signal Analyzer (Q-DiSA): Material Requirements and 6CCVD Solutions

This technical documentation analyzes the requirements for developing a Quantum Diamond Signal Analyzer (Q-DiSA) based on Nitrogen-Vacancy (NV) centers, focusing on the material specifications and how 6CCVD’s advanced MPCVD diamond capabilities can support and extend this research.

Executive Summary

The research demonstrates a compact, room-temperature quantum device for real-time, broadband Radio Frequency (RF) spectral analysis using ensemble NV centers in single-crystal diamond (SCD).

Core Value Proposition: Achieves real-time, broadband RF spectral analysis (Q-DiSA) using NV centers, suitable for compact, low-power on-board integration.
Key Performance: Demonstrated a tunable frequency range up to 25 GHz (10 MHz to 27 GHz) with a large dynamic range of 40 dB.
Resolution: Achieved frequency resolution down to 1 MHz and temporal resolution in the millisecond (ms) range.
Material Requirement: Requires high-quality, optical-grade Single Crystal Diamond (SCD) with controlled, low-concentration nitrogen doping (few ppb).
Crystallographic Control: Performance relies on a specific {100} SCD cut with {110} lateral facets to maintain precise alignment between the static magnetic field and the NV center axis during tuning.
6CCVD Capability: 6CCVD specializes in providing custom-cut, high-purity SCD wafers with precise crystallographic orientation and controlled doping necessary for replicating and scaling this quantum sensing architecture.

Technical Specifications

The following hard data points were extracted from the Q-DiSA experiment:

Parameter	Value	Unit	Context
Diamond Material	Single Crystal Diamond (SCD)	N/A	Optical grade, CVD grown
Diamond Dimensions	4.5 x 4.5 x 0.5	mm	Plate size used in experiment
Crystal Orientation	{100}	N/A	Plate surface orientation
NV Concentration	Few	ppb	Nitrogen doping level
Excitation Wavelength	532	nm	CW Laser
Laser Power (P)	300	mW	Used for spin polarization (Saturation parameter s = 0.15)
Zero-Field Splitting (D)	2.87	GHz	Ground state (ms = 0, ±1)
Gyromagnetic Ratio (γ)	28	GHz T^-1	NV center
Magnetic Field Range (B)	Up to 1	T	Provided by Neodymium sphere
Tunable Frequency Range	10 MHz to 27	GHz	Total tuning range demonstrated
Instantaneous Bandwidth	Up to 4	GHz	Determined by magnetic field gradient
Frequency Resolution	Down to 1	MHz	Spectral analysis capability
Dynamic Range	40	dB	Signal detection range
Temporal Resolution (Min)	2	ms	Measured at 1.8 GHz (C=6%, SNR=5)
Temporal Resolution (Max)	600	ms	Measured at 23 GHz (C=0.1%, SNR=1)
Active Area Size	530 x 50	µm²	Defined by optical system and antenna size
Spatial Resolution	0.66 x 0.66	µm²	Defines frequency resolution

Key Methodologies

The Q-DiSA architecture relies on precise material preparation and alignment to achieve broadband tuning while preserving the NV center’s spin properties.

Material Specification: A commercially available 4.5 x 4.5 x 0.5 mm {100} SCD plate, doped with NV centers at a concentration of a few ppb, was used.
Crystallographic Cut: The diamond featured {110} lateral facets, which were crucial for aligning one family of NV centers along the magnetization axis of the external magnet.
Magnetic Field Generation: A 1.3 cm Neodymium magnetic sphere provided a strong static magnetic field (up to 1 T) and a controlled magnetic field gradient for spatial encoding of resonance frequencies.
Frequency Tuning Mechanism: The resonance frequency was tuned over the 25 GHz range by adjusting the distance between the static magnet and the diamond sample (Zeeman shift).
Optical Excitation and Readout: NV centers were continuously excited using a 532 nm CW laser (300 mW). Photoluminescence (PL) was collected through the top {110} facet and spectrally filtered.
Microwave Excitation: A 1 mm-diameter loop antenna delivered the homogeneous RF magnetic field, positioned perpendicular to the aligned NV center axis to maximize coupling.
Spectral Analysis: The Q-DiSA method utilizes wide-field imaging via a CMOS camera. Spectral components of the MW signal are detected instantaneously by monitoring the drop in PL intensity on pixels corresponding to resonant NV centers (spatial encoding).

6CCVD Solutions & Capabilities

6CCVD is uniquely positioned to supply the high-specification diamond materials and customization services required to replicate, scale, and advance the Q-DiSA technology for quantum sensing and RF analysis.

Applicable Materials

The Q-DiSA requires diamond optimized for quantum sensing, demanding high purity, low strain, and controlled nitrogen incorporation.

Optical Grade Single Crystal Diamond (SCD): 6CCVD provides high-quality SCD wafers, essential for minimizing optical scattering and maximizing PL collection efficiency (ζ).
Controlled Nitrogen Doping: We offer SCD with precise, controlled nitrogen concentrations, ranging from the few ppb level (suitable for low-noise ensemble sensing, as used in this paper) up to 1-10 ppm (for applications requiring higher signal-to-noise ratio, SNR).
Boron-Doped Diamond (BDD): For related applications requiring integrated electrodes or high conductivity, 6CCVD supplies highly uniform Boron-Doped Polycrystalline (PCD) or Single Crystal (SCD) films.

Customization Potential

The success of the Q-DiSA architecture hinges on precise crystallographic orientation and geometry. 6CCVD excels in meeting these custom requirements.

Requirement from Paper	6CCVD Custom Capability	Technical Advantage
Specific Orientation/Cut	Custom SCD plates with precise {100} orientation and custom laser cutting to define {110} lateral facets.	Ensures optimal alignment of the magnetic field along the NV center axis, critical for broadband tuning (25 GHz).
Dimensions	SCD plates available in custom dimensions and thicknesses (0.1 µm to 500 µm). Substrates up to 10 mm thick.	Allows researchers to scale the active area or integrate the diamond into larger, complex magnetic architectures.
Surface Quality	Ultra-low roughness polishing: Ra < 1 nm (SCD).	Minimizes optical losses and scattering, maximizing the ODMR contrast (C) and overall SNR.
Integrated RF Structures	In-house custom metalization services (Au, Pt, Pd, Ti, W, Cu).	Enables direct fabrication of integrated microwave loop antennas or waveguides onto the diamond surface for enhanced RF coupling and miniaturization.

Engineering Support

The complexity of NV-based quantum sensing requires deep material expertise.

Material Optimization: 6CCVD’s in-house PhD team provides expert consultation on optimizing diamond growth parameters (e.g., nitrogen flow, post-growth annealing) to maximize NV center density and coherence properties for similar RF spectral analysis projects.
Crystallographic Precision: We assist engineers in selecting the optimal crystallographic orientation and cut geometry required to manage magnetic field gradients and minimize transverse magnetic field effects, thereby preserving the NV center spin-dependent photophysical properties.
Global Logistics: We ensure reliable, global delivery of sensitive diamond materials, with DDU default shipping and DDP options available.

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

Tech Support

Original Source

DOI: https://doi.org/10.1038/s44172-022-00017-4