| Metadata | Details |
|---|
| Publication Date | 2023-01-29 |
| Journal | C – Journal of Carbon Research |
| Authors | J. L. Sánchez Toural, Victor Marzoa, Ramón Bernardo Gavito, J. L. Pau, Daniel Granados |
| Institutions | Universidad Autónoma de Madrid, Madrid Institute for Advanced Studies |
| Citations | 10 |
| Analysis | Full AI Review Included |
- Core Technology Validation: Demonstrated a functional, hands-on quantum sensing platform utilizing Nitrogen-Vacancy (NV-) centers embedded in synthetic Type Ib HPHT diamond crystals.
- Room Temperature Magnetometry: The system operates under ambient conditions, leveraging the NV- center’s ability to maintain quantum spin coherence and allowing high-precision magnetometry without cryogenic cooling or magnetic shielding.
- ODMR Implementation: Successfully implemented Optically Detected Magnetic Resonance (ODMR) by combining 532 nm laser polarization (pumping electrons to the ms = 0 ground state) and microwave excitation at the 2.87 GHz Zero Field Splitting (ZFS) frequency.
- Custom Resonator Design: Developed and fabricated a compact, silver-printed PCB flat ring resonator optimized for the 2.87 GHz resonance, enabling efficient microwave control of the NV spin states.
- Zeeman Effect Quantification: Verified the linear relationship between the applied external magnetic field (B) and the splitting of the photoluminescence (PL) resonance dips (Zeeman shift), providing a direct method for quantitative magnetic field measurement.
- Miniaturization Potential: The methodology supports the transition toward highly compact, simplified sensor setups, replacing bulky spectrometers with photodiodes and opening the path for miniaturization down to the millimeter or nanoscale.
| Parameter | Value | Unit | Context |
|---|
| Diamond Type | Synthetic Type Ib | N/A | Grown via High-Pressure, High-Temperature (HPHT) synthesis. |
| NV Center Concentration | ~1 | ppm | Central concentration in samples used. |
| Nitrogen Concentration (Type Ib) | Up to 500 | ppm | General specification for Type Ib diamonds. |
| NV- Ground State ZFS (D) | 2.87 | GHz | Zero Field Splitting between ms = 0 and ms = ±1. |
| NV- Excited State ZFS | 1.42 | GHz | Energy gap in the excited triplet state. |
| Excitation Wavelength (Laser) | 532 | nm | Diode-pumped solid-state laser (2.33 eV). |
| PL Emission Range | 600 to 800 | nm | Observed photoluminescence spectrum. |
| NV- Zero Phonon Line (ZPL) | 637 | nm | Characteristic emission peak. |
| NV0 Zero Phonon Line (ZPL) | 576 | nm | Characteristic emission peak (neutral state). |
| MW Resonator Frequency | 2.87 | GHz | Designed resonance frequency for spin control. |
| MW Resonator Bandwidth | 100 | MHz | Bandwidth permitting work with hyperfine structure. |
| Electron Gyromagnetic Ratio (γe) | 28.0249 | GHz/T | Used in the spin Hamiltonian. |
| Magnetic Field Range Tested | 0 to ~0.2 | mT | Range tested using electromagnet/permanent magnet. |
| Raman Peak (sp3 lattice) | 523 nm or 1371 cm-1 | nm or cm-1 | Observed vibration of the diamond lattice. |
| NV- Coherence Time (Cited) | ~300 | ns | Inhomogeneous spin relaxation time. |
| Ultimate Sensitivity (Cited) | As low as 10-12 | T | Potential ultrahigh sensitivity performance. |
- Sample Acquisition and Characterization: Two synthetic Type Ib diamond samples (polycrystalline and single crystal) were characterized using a low-vibration optical setup and a 488 nm Argon ion laser to confirm the presence and spectra of NV0 and NV- centers.
- Resonator Fabrication: A flat ring resonator was designed based on previous studies and fabricated by silver printing on a 1.3 mm PCB substrate using a Voltera V-One PCB printer, ensuring a spatially uniform MW field over the diamond sample at 2.87 GHz.
- Spin Initialization (Optical Pumping): Continuous illumination with a 532 nm laser was applied to polarize the NV centers, preferentially pumping the electron spin population into the ms = 0 ground state.
- Zero-Field ODMR Measurement: A microwave source was swept across the 2.7 GHz to 3.0 GHz range (5.0 dBm constant power). The absorption of MW energy at 2.87 GHz excited electrons to the ms = ±1 states, which decay non-radiatively, resulting in a measurable decrease (dip) in the observed PL intensity.
- Magnetic Field Application: An external magnetic field (B) was applied using a controlled electromagnet or a permanent magnet, with field strength measured using a Teslameter (FH-55).
- Zeeman Splitting Quantification: The MW frequency sweep was repeated under varying B fields. The applied field caused the ms = ±1 sublevels to split (Zeeman effect), resulting in two distinct PL dips separated by 2γeB, allowing the magnetic field component aligned with the NV axis to be measured.
- System Miniaturization: The final setup was simplified by replacing the spectrometer and Raspberry Pi with an amplified photodiode (AMS TSL257-LF) and an Arduino Portenta H7 board for signal readout and visualization on an oscilloscope, demonstrating a path toward a compact sensor device.
- High-Sensitivity Magnetometry: Development of next-generation magnetic sensors capable of measuring extremely small fields (potential sensitivity of 10-12 T) for geological surveys, defense, and materials inspection.
- Biomedical Imaging (MEG/ECG): Creation of highly localized, high spatial and temporal resolution magnetic sensors for non-invasive functional brain imaging (Magnetoencephalography) and cardiac monitoring, operating at room temperature.
- Solid-State Quantum Computing: Utilization of NV centers as robust, solid-state qubits for quantum information processing and quantum memory due to their long spin coherence times.
- Nanoscale Metrology: Precision measurement of local magnetic fields, temperature, and strain at the micro- and nanoscale for characterizing advanced electronic materials and devices.
- Miniaturized Sensor Integration: Integration of diamond-based sensors into compact, portable, and multisensor systems, overcoming the size limitations of traditional cryogenic SQUID or large OPM devices.
View Original Abstract
The physical properties of diamond crystals, such as color or electrical conductivity, can be controlled via impurities. In particular, when doped with nitrogen, optically active nitrogen-vacancy centers (NV), can be induced. The center is an outstanding quantum spin system that enables, under ambient conditions, optical initialization, readout, and coherent microwave control with applications in sensing and quantum information. Under optical and radio frequency excitation, the Zeeman splitting of the degenerate states allows the quantitative measurement of external magnetic fields with high sensitivity. This study provides a pedagogical introduction to the properties of the NV centers as well as a step-by-step process to develop and test a simple magnetic quantum sensor based on color centers with significant potential for the development of highly compact multisensor systems.
- 2013 - The nitrogen-vacancy colour centre in diamond [Crossref]
- 2008 - High-sensitivity diamond magnetometer with nanoscale resolution [Crossref]
- 2010 - Ultrahigh sensitivity magnetic field and magnetization measurements with an atomic magnetometer [Crossref]
- 2007 - Highly Sensitive and Easy-to-Use SQUID Sensors [Crossref]
- 2009 - Nanoscale magnetic resonance imaging [Crossref]
- 2019 - Optically pumped magnetometers: From quantum origins to multi-channel magnetoencephalography [Crossref]
- 2017 - Quantum sensing [Crossref]