One- and Two-Dimensional Nuclear Magnetic Resonance Spectroscopy with a Diamond Quantum Sensor
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2016-05-09 |
| Journal | Physical Review Letters |
| Authors | J. M. Boss, Kai Chang, Julien Armijo, K. S. Cujia, T. Rosskopf |
| Institutions | ETH Zurich, Pontificia Universidad CatĂłlica de Chile |
| Citations | 59 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Free Nuclear Precession NMR using Diamond Quantum Sensors
Section titled âTechnical Documentation & Analysis: Free Nuclear Precession NMR using Diamond Quantum SensorsâThis document analyzes the research paper âOne- and two-dimensional nuclear magnetic resonance spectroscopy with a diamond quantum sensorâ (arXiv:1512.03178v1) to highlight the critical material requirements and demonstrate how 6CCVDâs advanced MPCVD diamond solutions enable the replication and extension of this high-precision quantum sensing technology.
Executive Summary
Section titled âExecutive SummaryâThe research successfully implemented a novel free nuclear precession method using near-surface Nitrogen-Vacancy (NV) centers in diamond, achieving significant advancements in nanoscale Nuclear Magnetic Resonance (NMR) spectroscopy.
- High-Precision Sensing: Demonstrated the measurement of nuclear Zeeman frequency (wo,n) and hyperfine coupling parameters (a||, aâ„) with exceptional precision (up to 5 digits).
- Ambiguity Resolution: The free precession technique uniquely identifies nuclear species (e.g., 1H, 13C, 15N), resolving critical peak assignment ambiguities inherent in traditional multipulse quantum sensing protocols.
- Advanced Spectroscopy: Successfully implemented two-dimensional (2D) Fourier spectroscopy, a powerful tool for mapping nuclear coordinates and determining connectivity in complex molecular structures.
- Material Requirement: The experiment relies on electronic-grade Single Crystal Diamond (SCD) chips featuring ultra-shallow NV layers (~5 nm depth) and high-quality surface preparation for subsequent nanopillar waveguide patterning.
- Quantum Coherence: The measurement precision is limited by the electronic T1 time (~0.2 ms), highlighting the need for ultra-high purity SCD substrates to maximize coherence properties.
- 6CCVD Value Proposition: 6CCVD provides the necessary high-purity, low-strain SCD substrates with industry-leading surface polishing (Ra < 1 nm) and custom dimensions required for scaling up these advanced quantum sensing platforms.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the research paper, detailing the physical and quantum parameters achieved or utilized in the experiment.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Diamond Material Grade | Electronic Grade | N/A | Required for high T1 and T2 coherence times |
| NV Center Depth | ~5 | nm | Created via 15N+ ion implantation |
| Implantation Energy | 2.5 | keV | Used for shallow NV creation |
| Bias Magnetic Field (Bo) | 0.18 (or 174) | T (or mT) | Operating field for the ms = 0 <â> ms = -1 transition |
| Excitation Wavelength | 532 | nm | Used for NV initialization and readout |
| Electronic Coherence Time (T2) | ~10 | ”s | Limits multipulse signal decay |
| Electronic Relaxation Time (T1) | ~0.2 | ms | Limits free precession recording time |
| Measurement Precision | 5 | digits | Achieved for wo,n and a|| parameters |
| Measured 13C Zeeman Freq (wo,n/2Ï) | 2.09321(11) | MHz | High-precision result |
| Measured 13C Parallel Coupling (a||/2Ï) | 4.02350(16) | MHz | High-precision result |
| Measured 13C Transverse Coupling (aâ„/2Ï) | 251.35(63) | kHz | High-precision result |
| 1H NMR Frequency (at 174 mT) | 7.40 | MHz | Reference frequency |
Key Methodologies
Section titled âKey MethodologiesâThe experiment combined advanced material engineering with sophisticated quantum control pulse sequences to achieve high-resolution NMR.
- Substrate Preparation: Electronic-grade diamond chips were used, featuring ultra-low native nitrogen content to maximize T1 and T2.
- NV Layer Creation: A shallow layer of NV centers (~5 nm deep) was created via 15N+ ion implantation at 2.5 keV.
- Optical Enhancement: The chip surface was patterned with an array of nanopillar waveguides to increase the photon count rate and improve signal collection efficiency.
- Spin Initialization and Readout: Laser pulses (532 nm, 1.5 ”s) were used to initialize and optically detect the state of the single NV electronic spin.
- Spin Manipulation: Microwave pulses, delivered via a lithographically patterned transmission line, were used for spin manipulation (e.g., Ï/2 rotations).
- Free Precession Sequence: The core measurement utilized the three-propagator sequence: UPUfreeUCP.
- UCP (Carr-Purcell sequence) prepares the nuclear spin state.
- Ufree (Free Precession) allows the nuclear spin to evolve under a tailored Hamiltonian (Hfree) for an incremented time t1.
- UP (Readout) transforms the nuclear state back to the detectable electronic state.
- Parameter Measurement: By varying the Hamiltonian Hfree (e.g., Hfree(2) for wo,n and a||, or Hfree(3) for aâ„), specific quantum parameters were selectively measured with high precision via Fourier transform of the time-domain signal.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & Capabilitiesâ6CCVD is uniquely positioned to supply the foundational SCD materials required for replicating and advancing this high-precision NV-NMR research. Our capabilities directly address the stringent purity, dimension, and surface quality requirements of quantum sensing applications.
Applicable Materials for Quantum Sensing
Section titled âApplicable Materials for Quantum SensingâTo replicate the high T1 and T2 performance necessary for 5-digit precision, researchers require the highest quality SCD substrates.
| Requirement from Paper | 6CCVD Applicable Material | Key Specification |
|---|---|---|
| Electronic-Grade Diamond | Optical Grade Single Crystal Diamond (SCD) | Ultra-low native nitrogen content (Type IIa) for maximum T1 and T2 coherence times. |
| Shallow NV Creation | SCD Substrates | Optimized for subsequent ion implantation or delta-doping, ensuring minimal strain and defect incorporation near the surface. |
| High-Precision Measurement | SCD (0.1 ”m to 500 ”m) | Available in precise thicknesses, allowing researchers to select optimal thermal and optical properties for their setup. |
Customization Potential
Section titled âCustomization PotentialâThe complexity of the experimental setup (nanopillars, microwave lines) necessitates highly customized diamond chips. 6CCVD offers comprehensive engineering services to meet these needs.
- Surface Preparation (Critical for Shallow NVs):
- 6CCVD guarantees Ra < 1 nm polishing on SCD, providing an atomically smooth surface essential for high-fidelity shallow NV creation and subsequent lithographic patterning of nanopillar waveguides.
- Custom Dimensions and Substrates:
- We provide custom-cut plates and wafers up to 125 mm (PCD) and thick substrates up to 10 mm, allowing for scalable device fabrication and integration into complex cryo- or vacuum systems.
- Integrated Metalization:
- The experiment requires microwave transmission lines for spin manipulation. 6CCVD offers internal, high-quality metalization services, including Ti, Pt, Au, Pd, W, and Cu, deposited directly onto the diamond surface for robust microwave delivery.
- Boron Doped Diamond (BDD) Extension:
- For applications requiring integrated electrical control or sensing of electrochemical processes, 6CCVD supplies Boron-Doped Diamond (BDD) films, available in both SCD and PCD formats, with tunable conductivity.
Engineering Support
Section titled âEngineering Supportâ6CCVDâs in-house PhD team specializes in the material science of MPCVD diamond for quantum and high-frequency applications. We can assist researchers in optimizing material selection for similar NV-NMR Spectroscopy projects, ensuring the substrate properties (purity, strain, orientation) maximize the achievable coherence time and measurement precision.
Call to Action: For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
We report on Fourier spectroscopy experiments performed with near-surface nitrogen-vacancy centers in a diamond chip. By detecting the free precession of nuclear spins rather than applying a multipulse quantum sensing protocol, we are able to unambiguously identify the NMR species devoid of harmonics. We further show that, by engineering different Hamiltonians during free precession, the hyperfine coupling parameters as well as the nuclear Larmor frequency can be selectively measured with up to five digits of precision. The protocols can be combined to demonstrate two-dimensional Fourier spectroscopy. Presented techniques will be useful for mapping nuclear coordinates in molecules deposited on diamond sensor chips, en route to imaging their atomic structure.