Unambiguous nuclear spin detection using an engineered quantum sensing sequence
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2017-11-17 |
| Journal | Physical review. A/Physical review, A |
| Authors | Zijun Shu, Zhendong Zhang, Qingyun Cao, Pengcheng Yang, Martin B. Plenio |
| Institutions | UniversitÀt Ulm, Huazhong University of Science and Technology |
| Citations | 8 |
| Analysis | Full AI Review Included |
Technical Documentation and Analysis: Unambiguous Nuclear Spin Detection via Engineered Quantum Sensing Sequences
Section titled âTechnical Documentation and Analysis: Unambiguous Nuclear Spin Detection via Engineered Quantum Sensing SequencesâThis documentation analyzes the research demonstrating robust, high-resolution nuclear spin detection using engineered dynamical decoupling sequences on a single Nitrogen-Vacancy (NV) center in diamond. 6CCVD provides the specialized, high-purity Single Crystal Diamond (SCD) necessary to replicate and advance this critical quantum sensing research.
Executive Summary
Section titled âExecutive SummaryâThe following summarizes the core technical achievements and commercial value derived from the analyzed research, focusing on the material requirements and application potential:
- Robust Quantum Sensing: Demonstrated unambiguous single nuclear spin detection (specifically external 1H protons) using a single Nitrogen-Vacancy (NV) spin sensor in diamond.
- Spurious Resonance Suppression: Successfully employed an engineered quantum sensing sequence (YY8, an MLEV-8 variant) to simultaneously suppress both 2nd and 4th order spurious harmonic resonances.
- Enhanced Robustness: The YY8 sequence proved superior to the widely used XY8 sequence, offering greater simplicity and enhanced robustness against pulse errors, such as amplitude imbalance.
- Material Platform Validation: High-purity Type IIa diamond was utilized, requiring high material integrity to maintain the long T2 coherence times essential for multi-pulse dynamical decoupling schemes.
- Application Relevance: The method is directly applicable to single-molecule magnetic resonance spectroscopy and imaging (SMMRS) and the coherent control of nuclear spin quantum registers.
- 6CCVD Advantage: Replication and extension of this work requires high-purity, defect-controlled Single Crystal Diamond (SCD) and precision surface polishingâcore capabilities of 6CCVD.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the experimental methodology and results:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Sensor Platform | NV Center in Diamond | - | Single spin sensor for NMR spectroscopy. |
| Diamond Material Used | Type IIa (Natural Abundance) | - | High purity, host material for NV center creation. |
| Nitrogen Implantation Energy | 2.5 | keV | Used to create shallow NV centers near the surface. |
| NV Center Zero-Field Splitting (D/2Ï) | 2.87 | GHz | Triplet ground state manifold characteristic. |
| Rabi Frequency (Ω) | (2Ï)25 | MHz | Frequency of microwave control pulses. |
| Applied Static Magnetic Field (Bz) | 510 | G | Used for 14N polarization and defining the NV axis. |
| NV Center Coherence Time (T2) | â 5 | ”s | Critical metric indicating material quality required for multi-pulse sequences. |
| NV Center Relaxation Time (T1) | â 300 | ns | - |
| Measured 1H Gyromagnetic Ratio Slope | 4.20 ± 0.13 | kHz/G | Confirms unambiguous proton (1H) detection signal. |
| Suppressed Harmonics | 2nd and 4th | Order | Suppressed simultaneously by YY8 sequence at initial phase Ï = 0. |
Key Methodologies
Section titled âKey MethodologiesâThe experiment successfully employed highly controlled MPCVD diamond substrates and complex microwave pulse sequences to achieve its results.
- Substrate Selection: Utilized Type IIa Single Crystal Diamond (SCD) with natural 13C abundance as the host material for the NV sensor.
- NV Center Creation: Shallow NV centers were created near the diamond surface via 2.5 keV N+ ion implantation, necessary for strong coupling to external target spins (e.g., 1H in oil).
- Spin Control Environment: A magnetic field of 510 G was applied along the NV axis. The NV spin was initialized and read out optically, typically using the |ms = 0> and |ms = -1> states.
- Microwave Pulse Generation: High-fidelity microwave Ï-pulses (Ω = (2Ï)25 MHz) were generated using an Arbitrary Wave Generator (AWG) and a high-power 80W amplifier, ensuring precise amplitude and phase control to minimize pulse errors.
- Dynamical Decoupling (DD) Sequences: Two sequences were tested for detecting 13C and 1H:
- XY8 Family: Standard DD sequence, requires specific initial phase tuning to suppress either the 2nd or the 4th harmonic, but not both simultaneously.
- YY8 Family: Engineered MLEV-8 variant that demonstrated simultaneous suppression of both 2nd and 4th order spurious resonances when the initial phase was set to Ï = 0, offering reduced experimental complexity and enhanced robustness.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThis research confirms the crucial role of ultra-high-quality diamond substrates in advancing quantum sensing technology. 6CCVD is uniquely positioned to supply the foundational SCD and customized engineering services required for high-fidelity NV center applications.
Applicable Materials
Section titled âApplicable MaterialsâTo replicate and enhance the long-coherence performance achieved in this research, 6CCVD recommends the following specialized materials:
| Material Specification | Requirement Addressed | 6CCVD Capability |
|---|---|---|
| High Purity Optical Grade SCD | Essential for maximizing T2 coherence times (5 ”s observed) and reducing intrinsic noise from nitrogen or substitutional defects. | SCD plates available up to 500 ”m thick, with guaranteed ultra-low impurity levels (< 1 ppb N). |
| Low-Strain SCD Substrates | Minimizing crystal strain preserves the magnetic uniformity across the wafer, vital for scalable, homogeneous NV sensor arrays. | SCD available in dimensions up to 10mm substrates. |
| Precision Polishing | Required for creating ultra-shallow NV centers (2.5 keV implantation) where surface roughness heavily impacts noise and T2. | Ra < 1 nm (SCD) polishing standard, providing near-atomic flatness for superior surface quality. |
| Scaling Quantum Devices | Need for larger area substrates for integrated quantum sensors and metrology applications. | Inch-Size PCD Wafers available up to 125mm in diameter, polished to Ra < 5 nm, enabling large-scale sensor manufacturing. |
Customization Potential
Section titled âCustomization PotentialâThe complexity of implementing sequences like YY8 and XY8 often requires integrating precise microwave control circuits or specialized sensor geometries.
- Custom Dimensions: 6CCVD supplies custom plates and wafers up to 125mm (PCD) and specialized geometries via advanced laser cutting services, allowing rapid prototyping of chip-scale quantum devices.
- Tailored Metalization: The experiment relies on highly efficient microwave pulsing. 6CCVD offers in-house deposition of standard metal stacks (e.g., Au, Pt, Ti, Cu, Pd, W). We can engineer specific contact pads or microwave transmission lines directly onto the diamond surface to optimize pulse delivery and minimize standing waves.
- Boron Doped Diamond (BDD): For specialized electrochemistry or high-sensitivity applications requiring conductive diamond adjacent to the sensing layer, 6CCVD offers Boron-Doped Diamond (BDD) films, customizable in thickness (0.1 ”m - 500 ”m).
Engineering Support
Section titled âEngineering SupportâNV-based detection systems require precise control over material quality, defect density, and surface treatment. 6CCVDâs in-house PhD team provides specialized consultation to ensure optimal material selection for single-molecule magnetic resonance spectroscopy and nuclear spin quantum control projects. We assist customers in defining specifications that guarantee the long coherence times and low noise floor necessary to successfully utilize engineered pulse sequences, such as the robust YY8 protocol.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Sensing, localising and identifying individual nuclear spins or frequency\ncomponents of a signal in the presence of a noisy environments requires the\ndevelopment of robust and selective methods of dynamical decoupling. An\nimportant challenge that remains to be addressed in this context are spurious\nhigher order resonances in current dynamical decoupling sequences as they can\nlead to the misidentification of nuclei or of different frequency components of\nexternal signals. Here we overcome this challenge with engineered quantum\nsensing sequences that achieve both, enhanced robustness and the simultaneous\nsuppression of higher order harmonic resonances. We demonstrate experimentally\nthe principle using a single nitrogen-vacancy center spin sensor which we apply\nto the unambiguous detection of external protons.\n