Parallel optically detected magnetic resonance spectrometer for dozensn of single nitrogen-vacancy centers using laser-spot lattice
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2020-11-06 |
| Journal | arXiv (Cornell University) |
| Authors | Mingcheng Cai, Zhongzhi Guo, Fazhan Shi, Chunxing Li, Mengqi Wang |
| Institutions | Hefei National Center for Physical Sciences at Nanoscale, Institute of Biophysics |
| Citations | 8 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThe research details the development and demonstration of a Parallel Optically Detected Magnetic Resonance (PODMR) spectrometer designed for high-throughput quantum sensing using Nitrogen-Vacancy (NV) centers in diamond.
- Core Innovation: The system utilizes a micro-lens array to generate a 20x20 Laser-Spot Lattice (LSL), enabling parallel optical excitation and readout of an array of single NV centers.
- Performance Gain: The platform demonstrated an 18 times efficiency improvement in magnetic resonance (MR) measurements compared to traditional laser scanning confocal microscopy.
- Parallel Operation: The system successfully observed 80 single NV centers and measured MR spectrums and Rabi oscillations for 18 NV centers in parallel.
- Uniform Manipulation: Spin manipulation is achieved uniformly across the entire array using a large-area Ω-shape coplanar coil, ensuring consistent microwave delivery (inhomogeneity as low as 0.25%).
- Precision Alignment: A sophisticated 3D auto-alignment protocol aligns the LSL and the NV nanopillar array, achieving coincidence in the Z-axis with a deviation of only 23.2 nm (within a 30 nm fitting error).
- Application Focus: This technology is crucial for accelerating nanoscale MR spectroscopy and imaging, particularly for single-molecule analysis in chemistry and biology.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| NV Center Spin Coherence Time | Millisecond | s | Highly promising sensor characteristic |
| NV Center Depth | 5 to 11 | nm | Shallow NV centers created by implantation |
| NV Creation Method | 10 keV 14N2+ | Implantation | Used on ultrapure bulk diamond ([N] less than 5 ppb) |
| Laser Excitation Wavelength | 532 | nm | Continuous-wave green laser |
| Laser-Spot Lattice (LSL) Size | 20 x 20 | Spots | Generated by micro-lens array |
| LSL Interval (ds) | 2 | ”m | Interval on the diamond surface |
| Micro-lens Array Interval (da) | 150 | ”m | Commercial Thorlabs MLA150-7AR-M |
| Objective Lens | 60x, 0.7 | NA | OLYMPUS LUCPlanFL N |
| Microwave Coil Type | Ω-shape | Coplanar | Optimized for 2-5 GHz frequency range |
| Microwave Field Inhomogeneity (Ïrms) | 0.25% to 0.55% | % | Simulated distribution across the diamond area |
| Rabi Oscillation Frequency | ~4 | MHz | Measured in parallel for 18 NV centers |
| Z-axis Alignment Deviation (Îz) | 23.2 | nm | Precision alignment between LSL and NV array |
| Efficiency Improvement | 18 | Times | Compared to conventional confocal ODMR |
| Maximum Fluorescence Count | 130 | k/s | Per single NV center |
| Background Count | 10 | k/s | Optical background |
| MR Spectrum Acquisition Time | 220 | s | For 18 NV centers (40 data points) |
Key Methodologies
Section titled âKey MethodologiesâThe PODMR system integrates advanced optics, microwave engineering, and precise mechanical control to achieve parallel quantum measurements.
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NV Center Array Fabrication:
- NV centers were created in ultrapure bulk diamond ([100] face) using 10 keV 14N2+ implantation to achieve shallow NV depths (5-11 nm).
- The diamond surface was patterned with a 25x25 array of trapezoidal cylinder-shaped nanopillars, spaced at 2 ”m intervals, to enhance photon collection efficiency.
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Laser-Spot Lattice (LSL) Generation:
- A 532 nm continuous-wave green laser was modulated into a pulsed laser using three AOMs (Acousto-Optic Modulators).
- The beam was directed through a micro-lens array (150 ”m interval) and subsequent focusing optics (f1=225 mm) to generate the 20x20 LSL (2 ”m interval) focused onto the diamond surface.
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Microwave Spin Manipulation:
- An Ω-shape coplanar coil, fabricated on a printed circuit board (PCB), was used to deliver a homogeneous microwave magnetic field (2-5 GHz range).
- This coil ensures uniform manipulation of all single NV spins in parallel, with simulated field inhomogeneity (Ïrms) ranging from 0.25% to 0.55% in the central region.
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High-Precision Alignment:
- The diamond sample was mounted on a system combining a 3-dimension (3D) piezo scanner (200 ”m range) for precise translation and multiple electric rotation/goniometric stages for angular adjustment (Ξ, Ï, Îł).
- The alignment protocol involved rotating the LSL to be parallel with the nanopillar array, followed by translation to achieve spatial coincidence. Z-axis alignment was confirmed by matching the point spread functions of two NV centers to within 23.2 nm.
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Parallel Readout and Data Acquisition:
- Fluorescence from the excited NV centers was collected by a high-NA objective (0.7 NA) and mapped onto an Electron-Multiplying Charge-Coupled Device (EMCCD) camera.
- The computer program automatically sums the counts from a 3x3 pixel area around the center of each NV spot to determine the fluorescence count for each single NV center in parallel.
- An auto-alignment protocol continuously corrects for thermal drift and mechanical vibration by maximizing the summed photon counts during long experiments.
Commercial Applications
Section titled âCommercial ApplicationsâThe PODMR technology significantly enhances the speed and throughput of NV-based quantum sensing, opening doors for industrial and research applications requiring high-resolution, parallel measurements.
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Quantum Sensing and Metrology:
- Development of high-throughput quantum magnetometers capable of simultaneously monitoring magnetic fields at dozens or thousands of distinct nanoscale points.
- Accelerated characterization and quality control of quantum materials and devices.
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Nanoscale Magnetic Resonance Spectroscopy:
- Enabling single-molecule scale NMR and ESR spectroscopy, pushing detectable sample volumes down to 10-21 L.
- Crucial for structural analysis and dynamic characterization of single molecules in complex environments.
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Biotechnology and Medicine:
- High-speed single-molecular MR spectroscopy of biological samples with short lifetimes (e.g., proteins or metabolites).
- High-throughput cellular measurement when combined with microfluidics, allowing single-molecule resolution imaging of magnetic or charge environments within living cells.
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Advanced Diamond Substrates:
- The requirement for high-density, shallow NV arrays fabricated into nanopillars drives demand for specialized, high-purity, quantum-grade diamond substrates (relevant to suppliers like 6ccvd.com).
View Original Abstract
We develop a parallel optically detected magnetic resonance (PODMR)\nspectrometer to address, manipulate and read out an array of single\nnitrogen-vacancy (NV) centers in diamond in parallel. In this spectrometer, we\nuse an array of micro-lens to generate 20 * 20 laser-spot lattice (LSL) on the\nobjective focal plane, and then align the LSL with an array of single NV\ncenters. The quantum states of NV centers are manipulated by a uniform\nmicrowave field from a {\Omega}-shape coplanar coil. As an experimental\ndemonstration, we observe 80 NV centers in the field of view. Among them,\nmagnetic resonance (MR) spectrums and Rabi oscillations of 18 NV centers along\nthe external magnetic field are measured in parallel. These results can be\ndirectly used to realize parallel quantum sensing and multiple times speedup\ncompared with the confocal technique. Regarding the nanoscale MR technique,\nPODMR will be crucial for high throughput single molecular MR spectrum and\nimaging.\n