Skip to content
6CCVD Research

Strong mechanical driving of a single electron spin

At a Glance

Section titled “At a Glance”
MetadataDetails
Publication Date2015-08-03
JournalNature Physics
AuthorsArne Barfuss, Jean Teissier, Elke Neu, Andreas Nunnenkamp, Patrick Maletinsky
InstitutionsUniversity of Cambridge, University of Basel
Citations178
AnalysisFull AI Review Included

6CCVD Technical Analysis & Documentation: Strong Mechanical Driving of a Single Electron Spin

Section titled “6CCVD Technical Analysis & Documentation: Strong Mechanical Driving of a Single Electron Spin”

Executive Summary

Section titled “Executive Summary”

This research demonstrates a groundbreaking method for achieving strong, coherent control over single electron spins embedded in diamond, leveraging intrinsic strain fields generated by integrated mechanical oscillators. This approach overcomes limitations associated with conventional electromagnetic driving, establishing a critical platform for integrated quantum systems.

  • Core Achievement: Successful observation and utilization of the strong driving regime in an isolated Nitrogen-Vacancy (NV) spin via time-periodic strain fields from a single-crystalline diamond cantilever.
  • Decoherence Mitigation: The strong mechanical drive acts as a protective mechanism, significantly enhancing the spin coherence time ($T_{2}^{*}$) from $3.6 \pm 0.1$ ”s (undriven) to $14.0 \pm 0.6$ ”s (driven).
  • Material Foundation: The integration relies critically on high-quality, ultra-pure, single-crystal diamond (SCD) fabricated into micro-scale cantilevers (down to $0.2 \times 3.5 \times 15$ ”mÂł) using advanced top-down nanofabrication.
  • Observed Phenomena: Demonstrated strain-induced Rabi oscillations ($\Omega_m/2\pi \approx 1.14$ MHz) and mechanically induced Autler-Townes splitting in the microwave domain, hallmarks of strong spin-phonon coupling.
  • Future Applications: The results validate the concept of diamond-based hybrid spin-oscillator devices, opening pathways for strain-driven quantum sensing, computing, and proposed schemes for spin-induced phonon cooling and squeezing.
  • Technical Density: The ability to achieve high-fidelity spin manipulation at the single-defect level in a nanostructure confirms the suitability of high-purity MPCVD diamond for demanding quantum engineering projects.

Technical Specifications

Section titled “Technical Specifications”

Hard parameters and performance metrics extracted from the research paper.

ParameterValueUnitContext
Diamond Substrate GradeUltra-pure, “electronic grade”N/ARequirement for single NV center research.
Crystal Orientation[001]N/ASubstrate and cantilever axis.
SCD Thickness (t)0.2 - 1”mCantilever thickness range.
SCD Width (w)3.5”mCantilever width.
SCD Length (l)15 - 25”mCantilever length range.
NV Implantation Species14NN/ACreates the negatively charged NV center.
NV Implantation Energy12keVYields estimated depth of ~ 17 nm.
NV Implantation Dose1010cm-2Low dose for single-spin isolation.
Zero-Field Splitting (D0, Range)2.870 to 2.8725GHzNV center parameter.
Mechanical Resonance ($\omega_m / 2\pi$)5.95 to 6.83 ± 0.02MHzCantilever resonance frequency.
Strain-Driven Rabi Frequency ($\Omega_m / 2\pi$)1.14 ± 0.01MHzDemonstration of strong driving regime.
Undriven Spin Coherence ($T_{2}^{*}$)3.6 ± 0.1”sBaseline coherence time for reference NV.
Driven Spin Coherence ($T_{2}^{*}$)14.0 ± 0.6”sEnhanced coherence time achieved via mechanical drive.
Cantilever Spring Constant (k)76N/mCalculated for typical dimensions ($w=2 \text{ ”m}, t=1 \text{ ”m}, l=20 \text{ ”m}$).
Calculated Thermal Noise ($X_{th}$)~ 10pmRoot-mean-square thermal noise amplitude.
Max Drive Strength ($\Omega_m^{max}/2\pi$)~ 10.75MHzMaximum calculated Rabi frequency achieved.

Key Methodologies

Section titled “Key Methodologies”

The experiment relies on precision material preparation and nanostructuring of high-purity Single Crystal Diamond (SCD) using state-of-the-art nanofabrication techniques.

A. Diamond Preparation and NV Creation

Section titled “A. Diamond Preparation and NV Creation”
  1. Material Selection: Ultra-pure, electronic-grade, [001]-oriented single-crystalline diamond was used.
  2. Ion Implantation: 14N ions were implanted at 12 keV (dose $10^{10} \text{ cm}^{-2}$) to generate controlled, isolated NV lattice point defect centers near the surface (~17 nm depth).
  3. Annealing: Samples were annealed in high vacuum ($< 10^{-6}$ mbar) through a temperature ramp sequence: 400 °C (4 hours), 800 °C (2 hours), and 1200 °C (2 hours) to mobilize vacancies and form NV centers.

B. Top-Down Nanofabrication of Cantilevers

Section titled “B. Top-Down Nanofabrication of Cantilevers”
  1. Patterning: Electron Beam Lithography (EBL) at 30 keV was used to pattern etch masks (Negative tone FOX-16 resist, ~500 nm thickness) aligned with the diamond’s [110] crystal direction.
  2. Etching (ICP-RIE): The pattern was transferred into the diamond surface using Inductively Coupled Plasma Reactive Ion Etching (ICP-RIE, Sentech SI 500) to create vertical sidewall cantilevers.
    • Plasma Recipe: 50% Argon (Ar) / 50% Oxygen (O2).
    • Gas Flux: 50 sccm (each gas).
    • Pressure: 1.3 Pa.
    • ICP Source Power: 500 W.
    • Bias Power: 200 W.

C. Spin Manipulation and Readout

Section titled “C. Spin Manipulation and Readout”
  1. Mechanical Drive: The single-clamped cantilever was actuated at its mechanical resonance frequency ($\omega_m$) using a piezoelectric element placed below the diamond sample, generating AC strain fields.
  2. Optical Setup: A homebuilt confocal microscope setup was used at room temperature and atmospheric pressure. Green 532 nm laser light was used for NV spin initialization and fluorescence detection (through a dichroic mirror/APD detector) for readout.
  3. Spin Control: Microwave magnetic fields were generated by a nearby antenna, allowing for Optically Detected Electron Spin Resonance (OD-ESR) measurements and pulsed ESR schemes (e.g., Ramsey spectroscopy, Rabi oscillations).
  4. Field Control: A three-axis magnetic field was generated by homebuilt coil pairs driven by constant-current sources, used to apply an external magnetic field ($B_{NV}$) along the NV axis to control energy splitting.

6CCVD Solutions & Capabilities

Section titled “6CCVD Solutions & Capabilities”

The complexity of this experiment—requiring ultra-pure materials, micron-level dimensions, and specific crystal orientations—directly aligns with 6CCVD’s core strengths in MPCVD diamond engineering.

Applicable Materials

Section titled “Applicable Materials”

To replicate or extend this quantum research, engineers require high-fidelity material designed for quantum applications.

6CCVD MaterialSpecific Requirement from Paper6CCVD Customization Potential
Optical Grade SCDUltra-pure, electronic grade, low N content necessary for high-coherence NV creation via implantation and annealing.We guarantee nitrogen concentrations suitable for quantum sensing (N < 5 ppb typical) and offer custom [001], [111], or [110] orientations.
Custom Substrate ThicknessThickness down to 0.2 ”m required for high-frequency mechanical oscillators.SCD material is provided in custom thicknesses from 0.1 ”m up to 500 ”m, allowing precise control over cantilever mass and resonance frequency ($\omega_m$).
High-Precision PolishingSurface finish compatible with E-beam lithography patterning and deep-etching (ICP-RIE).Ra < 1 nm polishing available on SCD surfaces, ensuring minimal scattering losses and optimal adherence/fidelity for sub-micron pattern transfer.

Customization Potential

Section titled “Customization Potential”

The experimental success hinges on the precise geometry and integration of the diamond structure. 6CCVD delivers full support for custom specifications necessary for hybrid quantum devices:

  • Custom Dimensions & Shapes: 6CCVD offers laser cutting and precision machining services to transform our large MPCVD wafers (up to 125mm PCD) into the millimeter-scale chips and mounts required for sample handling, including alignment with specific crystal directions (e.g., [110]).
  • Integrated Metalization: Although this paper used external microwave antennae, integrated quantum systems often require on-chip micro-antennae or gate electrodes for driving/sensing. 6CCVD provides in-house metalization services, including deposition and patterning of: Au, Pt, Pd, Ti, W, and Cu.
  • Strain Engineering Substrates: For exploring strain effects beyond simple cantilevers, 6CCVD can produce diamond plates with custom thicknesses and dimensions specifically designed for bonding or integration into complex external straining apparatus (e.g., MEMS or micro-actuator systems).

Engineering Support

Section titled “Engineering Support”

The creation of isolated, high-coherence NV centers via ion implantation and high-temperature annealing (up to 1200 °C) requires deep materials expertise.

  • 6CCVD’s in-house PhD engineering team specializes in the synthesis and post-processing of diamond for quantum applications. We offer consultation on optimizing material specifications (e.g., substrate purity, thickness uniformity) to maximize NV yield and coherence time ($T_{2}^{*}$ and $T_{2}$).
  • We can assist research groups with material selection and specification for projects involving spin-oscillator coupling, quantum sensing (magnetometry), and integrated mechanical resonators.

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

Tech Support

Section titled “Tech Support”

Original Source

Section titled “Original Source”

References

Section titled “References”
  1. 2000 - Quantum Computation and Quantum Information

Reads Similar to This

Magnetic Resonance Study of Bulky CVD Diamond Disc Thermometry of an optically levitated nanodiamond A noise-robust quantum dynamics learning protocol based on Choi–Jamiolkowski isomorphism - theory and experiment