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6CCVD Research

Coherent population oscillations with nitrogen-vacancy color centers in diamond

At a Glance

Section titled “At a Glance”
MetadataDetails
Publication Date2016-07-26
JournalPhysical review. B./Physical review. B
AuthorsMariusz MrĂłzek, Adam M. Wojciechowski, Daniel Rudnicki, Jerzy Zachorowski, Pauli Kehayias
InstitutionsHelmholtz Institute Mainz, Jagiellonian University
Citations31
AnalysisFull AI Review Included

Technical Documentation and Analysis: Coherent Population Oscillations in NV Diamond

Section titled “Technical Documentation and Analysis: Coherent Population Oscillations in NV Diamond”

This document analyzes the submitted research on utilizing two-field microwave spectroscopy to induce and measure Coherent Population Oscillations (CPO) in Nitrogen-Vacancy (NV) color centers in diamond. This work is highly relevant to quantum sensing and spin dynamics, core areas supported by 6CCVD’s advanced Material-Phase Chemical Vapor Deposition (MPCVD) diamond products.

Executive Summary

Section titled “Executive Summary”

This research establishes Coherent Population Oscillations (CPO) as a powerful, non-traditional method for characterizing the fundamental relaxation dynamics of NV- color centers, offering significant advantages over standard ODMR techniques.

  • Core Achievement: First direct observation of CPO effects in NV diamond, both in the spectral domain and real-time.
  • Application: The resulting narrow, complex ODMR resonance structures (composed of three distinct Lorentzian components) allow for the precise determination of individual spin state relaxation rates ($\gamma_0$, $\gamma_1$) and the decoherence rate ($\Gamma = 1/T_2$).
  • Material Requirement: The study required a high-quality, low-nitrogen single crystal diamond (SCD) substrate (initial N density < 200 ppm) with a {100} cut, subsequently processed via electron irradiation (1.5 x 1018 cm-2 fluence) and high-temperature annealing (750 °C).
  • Methodological Insight: CPO provides an alternative to traditional relaxation-in-the-dark measurements, yielding specificity to the relaxation and dephasing of individual spin states, crucial for developing robust quantum devices.
  • Technical Density: The spectral features resolve widths down to the order of 27 kHz, reflecting the slowest population relaxation rate ($\gamma_0$).
  • 6CCVD Advantage: 6CCVD specializes in producing ultra-high purity, optical-grade SCD optimized for NV- center creation, offering superior initial nitrogen purity (sub-1 ppm) and custom substrate geometries necessary for scaling this research.

Technical Specifications

Section titled “Technical Specifications”
ParameterValueUnitContext
Material TypeSingle Crystal Diamond (SCD)N/AHPHT-grown, processed for NV centers
Initial N Concentration< 200ppmStarting material specification
Final NV Concentration~20ppmAfter E-beam (14 MeV) and annealing (750 °C)
Substrate Dimensions3 x 3 x 0.3mm3Sample size used in experiment
Crystallographic Cut{100}SurfaceUsed for substrate orientation
Magnetic Field (B)28GAligned along the [111] axis
Pump Frequency2948.5MHzTuned to $m_s = 0 \leftrightarrow m_s = +1$ transition
Pump Rabi Frequency ($\Omega_s$/2$\pi$)1.6MHzUsed for saturation/hole burning
Probe Rabi Frequency ($\Omega_p$/2$\pi$)1.2MHzUsed for sensing the hole
Excitation Wavelength532nmGreen laser source (5 mW power)
Relaxation Rate ($\gamma_0$/2$\pi$)27 $\pm$ 7kHzFitted width of the narrowest Lorentzian component
Coherence Linewidth (2$\Gamma$/2$\pi$)2.903 $\pm$ 0.038MHzFitted width of the broadest Lorentzian component
Dephasing Condition$\Gamma$ >> $\gamma_0$, $\gamma_1$N/AIndicates significant dephasing mechanisms

Key Methodologies

Section titled “Key Methodologies”

The experiment utilized a comprehensive combination of material processing, quantum optics, and high-frequency electronics to observe the CPO effect.

  1. Material Preparation:

    • Diamond selection: Initial low-nitrogen SCD (< 200 ppm) with a {100} crystallographic orientation.
    • NV Creation: Irradiated with a 14 MeV electron beam at a fluence of 1.5 x 1018 cm-2.
    • Activation: Annealed at 750 °C for 2.5 hours to mobilize vacancies and form NV- centers (resulting concentration ~20 ppm).

  2. Experimental Setup (ODMR):

    • Confocal arrangement utilized a 532 nm green laser (5 mW) for continuous optical excitation and spin polarization.
    • Fluorescence (600-800 nm) detection via an avalanche photodiode (50 MHz bandwidth).
    • A static magnetic field (B=28 G) was applied along the [111] direction to split the $m_s$ ground states via the Zeeman effect.

  3. Two-Field Microwave (MW) Excitation:

    • Two synchronized continuous-wave MW generators were used (Pump and Probe).
    • The fields were combined and connected to a microstrip antenna attached to the sample, driving the $m_s = 0 \leftrightarrow m_s = +1$ transition (+/+ case).
    • Synchronization (10 MHz reference) allowed observation of interference effects for extremely small (sub-kHz) detunings without phase drift.

  4. CPO Measurement and Analysis:

    • Spectral Domain: The probe frequency ($\omega_p$) was scanned linearly in time across the fixed pump frequency ($\omega_s$). The resulting hole-burning ODMR spectrum revealed complex, narrow internal structures characteristic of CPO.
    • Time Domain: For very small detunings ($\Delta\omega/2\pi = 1$ kHz), the CPO was observed directly as real-time oscillations in the fluorescence signal.
    • Data Interpretation: Phase-averaging of scans was required to extract stable spectral characteristics, revealing the underlying relaxation dynamics ($T_1$ and $T_2$ rates) determined by the fitted Lorentzian widths (27 kHz, 137 kHz, and 2.9 MHz).

6CCVD Solutions & Capabilities

Section titled “6CCVD Solutions & Capabilities”

This research relies heavily on access to high-purity, structurally perfect diamond substrates. 6CCVD’s MPCVD manufacturing process delivers materials that meet and exceed the stringent requirements necessary for advanced quantum and sensing applications, facilitating the replication and scaling of CPO studies.

Applicable Materials for CPO Research

Section titled “Applicable Materials for CPO Research”

To replicate or advance the CPO research presented, 6CCVD recommends the following material specifications, offering purity levels significantly surpassing the < 200 ppm nitrogen content of the sample used in the paper:

6CCVD Material GradeSpecificationRelevance to CPO / NV Research
Optical Grade Single Crystal Diamond (SCD)Nitrogen Concentration: N < 1 ppm (often < 0.005 ppm).Critical: Ultra-low native defects allow for precise control over NV- concentration using targeted processing (e-beam/annealing), minimizing background noise and maximizing coherence time.
Custom SCD Substrates ({100} or {111})Orientation Control: Standard {100}, {111}, or custom angle cuts available.Necessary: The experiment relied on the B-field aligned to the [111] direction. 6CCVD provides precisely oriented material to optimize coupling efficiency and maximize the signal from targeted NV ensembles.
High Purity Polycrystalline Diamond (PCD)SCD is ideal, but PCD (up to 125mm) offers large area potential for scalability or microstrip antenna integration testing.Scaling: While CPO relies on single-crystal structure for coherence, large-area PCD substrates can serve as robust, thermally conductive platforms for integrated quantum devices based on NV centers.

Customization Potential for Quantum Platforms

Section titled “Customization Potential for Quantum Platforms”

6CCVD offers full engineering support to integrate high-quality diamond into custom experimental setups, such as the two-field microwave architecture described:

  • Custom Dimensions and Thickness: The paper used small 3x3x0.3 mm3 samples. 6CCVD can produce SCD plates up to 500 ”m thick and PCD wafers up to 125 mm in diameter, accommodating advanced microstrip antenna designs [Ref. 40 in paper].
  • Precision Machining and Polishing: We provide substrates with exceptional surface quality (SCD Ra < 1 nm), crucial for minimizing surface spin defects that degrade coherence, and custom laser cutting for integration into specific magnetic/MW environments.
  • Metalization Services: Although not featured in this specific paper, 6CCVD offers in-house deposition of metals (Au, Pt, Pd, Ti, W, Cu) for creating microstrip lines, resonant structures, or electrical contacts directly on the diamond, enabling fully integrated NV quantum devices.

Engineering Support and Global Logistics

Section titled “Engineering Support and Global Logistics”

6CCVD’s in-house PhD team can assist researchers in material selection and specification development for projects focusing on advanced spin dynamics, quantum sensing, and coherence lifetime maximization based on Coherent Population Oscillation (CPO) analysis.

We ensure rapid prototyping and reliable global shipping logistics (DDU default, DDP available) to facilitate time-sensitive academic and industrial research worldwide.

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

View Original Abstract

We present results of our research on two-field (two-frequency) microwave\nspectroscopy in nitrogen-vacancy (NV-) color centers in a diamond. Both fields\nare tuned to transitions between the spin sublevels of the NV- ensemble in the\n3A2 ground state (one field has a fixed frequency while the second one is\nscanned). Particular attention is focused on the case where two microwaves\nfields drive the same transition between two NV- ground state sublevels (ms=0\n-> ms=+1). In this case, the observed spectra exhibit a complex narrow\nstructure composed of three Lorentzian resonances positioned at the pump-field\nfrequency. The resonance widths and amplitudes depend on the lifetimes of the\nlevels involved in the transition. We attribute the spectra to coherent\npopulation oscillations induced by the two nearly degenerate microwave fields,\nwhich we have also observed in real time. The observations agree well with a\ntheoretical model and can be useful for investigation of the NV relaxation\nmechanisms.\n

Tech Support

Section titled “Tech Support”

Original Source

Section titled “Original Source”

References

Section titled “References”
  1. 2013 - Optical Magnetometry

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