Real-time estimation of the optically detected magnetic resonance shift in diamond quantum thermometry toward biological applications
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2020-12-24 |
| Journal | Physical Review Research |
| Authors | Masazumi Fujiwara, Alexander Dohms, Ken Suto, Yushi Nishimura, Keisuke Oshimi |
| Institutions | Osaka City University, Chapman University |
| Citations | 35 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Real-Time Quantum Diamond Thermometry
Section titled âTechnical Documentation & Analysis: Real-Time Quantum Diamond ThermometryâExecutive Summary
Section titled âExecutive SummaryâThis research validates advanced real-time quantum thermometry protocols using Nitrogen-Vacancy (NV) centers in nanodiamonds (NDs), focusing on optimizing measurement precision for dynamic biological applications.
- Core Achievement: Successful implementation and detailed error analysis of multipoint Optically Detected Magnetic Resonance (ODMR) methods (3-, 4-, and 6-point) for real-time temperature estimation in single NDs.
- Precision & Accuracy: Achieved high temperature precision (0.14 K to 0.23 K) and accuracy (< 0.5 K) during dynamic thermal events.
- Error Mitigation: Identified and quantified systematic instrumental errors, particularly photo-responsivity differences arising from hardware (DAQ clock speeds) and intrinsic NV spin properties.
- Methodological Advance: Proposed and demonstrated a practical error-correction filter based on pre-characterized second-order polynomial fits to eliminate signal drift caused by fluorescence intensity variations.
- Material Insight: Highlighted the critical role of diamond material quality and spectral stability, noting that spectral distortion and material inhomogeneity affect the temperature dependency (α, ranging from -54.1 to -95.0 kHz.K-1).
- Application Focus: Provides essential technical details for deploying quantum diamond thermometry in complex biosensing environments, including noise analysis (Allan variance) and artifact consideration (magnetic fields, microwave heating).
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Excitation Wavelength | 532 | nm | CW Laser |
| Laser Intensity | ~2 | kW/cm2 | Excitation of ND-NV centers |
| Microwave Excitation Power | 10 - 50 | mW | Fed to linear antenna |
| Microwave Magnetic Field | 2 - 5 | Gauss | In 20 ”m from antenna |
| ODMR Zero-Field Splitting (D) | ~2.87 | GHz | Resonant frequency |
| Off-Resonance Frequency (Ï0) | 2.65 | GHz | Used for 3-point baseline |
| Gate Width (tM) | 100 | ”s | Common to all gates |
| 4-Point Measurement Time (t4pnt) | 420 | ”s | Single sequence duration |
| 3-Point Measurement Time (t3pnt) | 315 | ”s | Single sequence duration |
| 6-Point Measurement Time (t6pnt) | 630 | ”s | Single sequence duration |
| Temperature Precision (4-point) | 0.14 | K | Measured on single ND |
| Temperature Precision (3-point) | 0.23 | K | Measured on single ND |
| Temperature Precision (6-point) | 0.15 | K | Measured on single ND |
| Temperature Accuracy | < 0.5 | K | Common to all methods |
| Temperature Sensitivity (4-point) | 0.9 | K/Hz | For the particular ND |
| Temperature Dependence (α) | -54.1 to -95.0 | kHz.K-1 | Zero-field splitting shift (dD/dT) |
| DAQ Clock Speeds | 100, 80 | MHz | Source of instrumental photo-responsivity error |
Key Methodologies
Section titled âKey MethodologiesâThe real-time quantum thermometry relied on a highly controlled MPCVD diamond system integrated with advanced optical and microwave control.
- Optical Excitation and Detection: ND-NV centers were excited using a CW 532 nm laser (~2 kW/cm2) focused via an oil-immersion objective (NA 1.4). Fluorescence was filtered using a dichroic beam splitter and long-pass filters, then detected by an Avalanche Photodiode (APD).
- Microwave Delivery: Microwave signals (10-50 mW) from multiple sources were combined via an SP6T switch (250 ns switching time), amplified, and delivered via a 25 ”m thin copper wire antenna placed on the coverslip, generating a magnetic field of 2-5 Gauss.
- Multipoint ODMR Acquisition: APD photon counts were gated for specific microwave frequencies (3, 4, or 6 points) using TTL pulses (100 ”s gate width) and recorded by two synchronized Data Acquisition (DAQ) boards operating at different clock speeds (100 MHz and 80 MHz).
- Real-Time Tracking: A confocal microscope system tracked the moving NDs by scanning a piezo stage (Piezosystemjena, TRITOR-100SG). Gaussian fits determined the xyz position, allowing for re-positioning every 4 seconds (3.8 s re-positioning time).
- Error Correction Implementation: Prior to temperature measurement, the counter photo-responsivity was characterized. Systematic errors were corrected by subtracting second-order polynomial fits of the artifact values from the raw photon counts (IC = INC + [a0 + a1INC + a2(INC)2]).
- Noise Filtering: Temperature time profiles were analyzed using Allan variance to identify noise sources (white noise, mechanical instability, environmental temperature fluctuation). A Kalman filter was employed for effective extraction of transient temperature dynamics.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & Capabilitiesâ6CCVD provides the foundational high-quality MPCVD diamond materials and advanced processing required to replicate, scale, and extend this quantum thermometry research into robust, integrated devices.
Applicable Materials for Quantum Sensing
Section titled âApplicable Materials for Quantum SensingâThe stability and sensitivity of NV centers are directly tied to the purity and crystalline quality of the host diamond. 6CCVD offers materials optimized for quantum applications:
- Optical Grade Single Crystal Diamond (SCD): Ideal for creating high-coherence NV centers, either through implantation or during growth. Our SCD offers superior purity, minimizing spectral distortion and maximizing the signal-to-noise ratio required for precise ODMR measurements.
- High-Purity Polycrystalline Diamond (PCD): Suitable as a precursor material for synthesizing high-quality nanodiamonds (NDs) used in biological applications, ensuring consistent NV concentration and spectral properties across batches.
- Custom Boron-Doped Diamond (BDD): Available for applications requiring conductive diamond substrates or specialized electrochemical sensing integrated alongside NV thermometry.
Customization Potential for Integrated Devices
Section titled âCustomization Potential for Integrated DevicesâThe paper highlights the complexity of the experimental setup, particularly the external microwave antenna and the susceptibility to instrumental errors. 6CCVDâs advanced processing capabilities enable the transition from laboratory setups to robust, integrated quantum sensors:
| Research Challenge | 6CCVD Custom Solution | Specification Match |
|---|---|---|
| External Microwave Antenna | Integrated Metalization Services | We apply custom metalization stacks (e.g., Ti/Pt/Au or Cu) directly onto the diamond surface to create robust, planar microwave striplines, ensuring stable and uniform magnetic fields (2-5 Gauss range). |
| Substrate Size & Scalability | Large-Area PCD Wafers | We supply PCD plates up to 125 mm in diameter, enabling the fabrication of large-scale quantum sensor arrays or high-throughput ND deposition platforms. |
| Surface Quality & Noise | Precision Polishing Services | SCD wafers can be polished to Ra < 1 nm and inch-size PCD to Ra < 5 nm, minimizing surface scattering and improving photon collection efficiency, crucial for low-photon regime ODMR. |
| Thickness Optimization | Custom Thickness Control | We offer SCD and PCD layers from 0.1 ”m up to 500 ”m, allowing engineers to optimize thermal response time (thin membranes) or maximize NV density (thick substrates). |
| Custom Geometry | Precision Laser Cutting | Diamond plates can be laser-cut to unique dimensions or shapes required for integration into specialized microscopy or biological incubation chambers. |
Engineering Support
Section titled âEngineering Supportâ6CCVDâs in-house team of PhD material scientists specializes in MPCVD diamond optimization for quantum technologies. We offer comprehensive engineering support for projects involving:
- Material selection and specification for quantum thermometry and nanoscale sensing.
- Optimization of nitrogen incorporation during growth to control NV center density and spectral homogeneity.
- Design consultation for integrated microwave and optical components on diamond substrates.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Real-time estimation protocols for the frequency shift of optically detected magnetic resonance (ODMR) of nitrogen-vacancy (NV) centers in nanodiamonds (NDs) are the key to the recent demonstrations of diamond quantum thermometry inside living animals. Here we analyze the estimation process in multipoint ODMR measurement techniques (3-, 4-, and 6-point methods) and quantify the amount of measurement artifact derived from the optical power-dependent ODMR spectral shape and instrumental errors of experimental hardware. We propose a practical approach to minimize the effect of these factors, which allows for measuring accurate temperatures of single ND during dynamic thermal events. Further, we discuss integration of noise filters, data estimation protocols, and possible artifacts for further developments in real-time temperature estimation. This study provides technical details regarding quantum diamond thermometry and analyzes the factors that may affect the temperature estimation in biological applications.