Ultrafast opto-magnetic effects induced by nitrogen-vacancy centers in diamond crystals
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2022-06-01 |
| Journal | APL Photonics |
| Authors | Ryosuke Sakurai, Yuta Kainuma, Toshu An, Hidemi Shigekawa, Muneaki Hase |
| Institutions | Japan Advanced Institute of Science and Technology, University of Tsukuba |
| Citations | 6 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive Summaryâ- Ultrafast Sensing Breakthrough: The research successfully extended the time resolution of magnetic quantum sensing using Nitrogen-Vacancy (NV) centers in diamond to sub-picosecond scales, significantly surpassing the microsecond limits of conventional luminescence-based NV sensing.
- Inverse Cotton-Mouton Effect (ICME) Observed: The study identified and characterized the Inverse Cotton-Mouton Effect (ICME) in NV-doped diamond, alongside the Inverse Faraday Effect (IFE) and Optical Kerr Effect (OKE).
- Second-Order Opto-Magnetic Mechanism: The ICME signal exhibits a unique sin 6α helicity dependence and a quadratic dependence on pump fluence, confirming its nature as a second-order opto-magnetic effect driven by the ensemble of NV electron spins.
- Two-Step Process: The ICME is interpreted as a two-step process where circularly polarized light generates a DC magnetic field (via IFE), which subsequently induces a coherent ensemble of NV spins, leading to the ICME response.
- Performance Metrics: The current experimental setup estimates a possible detectable magnetic field strength of approximately 35 mT (3.5 x 102 Oe).
- Future Integration: These findings lay the groundwork for developing high-resolution spatial-time quantum sensing technologies when combined with Scanning Probe Microscopy (SPM) techniques.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Time Resolution Achieved | Sub-picosecond | Time | Magnetic sensing capability |
| Estimated Detectable Magnetic Field | ~35 | mT | Sensitivity based on sin 6α component |
| Pump Pulse Duration | ~40 | fs | Light source pulse width |
| Central Wavelength | ~800 | nm | Laser wavelength |
| Repetition Rate | 100 | kHz | Laser system operation frequency |
| Pump Fluence (Max Tested) | 40.0 | mJ/cm2 | Maximum energy density used |
| Sample Material | Type-IIa Diamond | Crystal | Element Six, [100] orientation |
| Sample Thickness | 0.3 | mm | Crystal dimension |
| Nitrogen Implantation Energy | 30 | keV | 14N+ ion energy |
| Highest NV Dose (Sample C) | 1.0x1012 | ions/cm2 | Maximum NV concentration tested |
| Annealing Temperature | 900-1000 | °C | Post-implantation processing range |
| Annealing Atmosphere | Argon | Gas | Environment for NV creation |
| Estimated Implantation Depth | 30-40 | nm | Depth of NV layer from surface |
| NV Production Efficiency | ~10 | % | Conversion rate of implanted ions to NV centers |
Key Methodologies
Section titled âKey Methodologiesâ-
Sample Preparation:
- Substrate Selection: Used Element Six [100] type-IIa diamond single crystals (impurity levels: N < 1 ppm, B < 0.05 ppm).
- Implantation: Introduced NV precursors by implanting 30 keV 14N+ ions at doses up to 1.0x1012 ions/cm2.
- Annealing: Annealed samples at 900°C-1000°C for 1 hour in an argon atmosphere to mobilize vacancies and form negatively charged NV- centers (production efficiency ~10%).
-
Ultrafast Measurement Setup:
- Technique: Time-resolved Kerr-rotation measurement using a reflection-based femtosecond pump-probe setup.
- Light Source: Femtosecond regenerative amplifier generating ~40 fs pulses at ~800 nm with a 100 kHz repetition rate.
- Beam Geometry: Pump and probe beams were co-focused (spot size ~50 ”m) with incident angles of 20° and 25° relative to the surface normal.
- Polarization Control: Pump polarization (helicity) was systematically varied from linear to right- and left-handed circular polarization using a quarter-wave-plate (QWP).
- Detection: The change in Kerr-rotation (ÎΞk) of the reflected probe pulse was measured using balanced silicon photo-diodes as a function of pump-probe delay (up to 15 ps).
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Data Analysis:
- The helicity dependence of the signal peak amplitude was fitted using the standard Kerr rotation equation: ÎΞk = C sin 2α + L sin 4α + D (representing IFE and OKE).
- The residual signal, which increased significantly with NV concentration, was isolated and fitted using F sin 6α, confirming the presence of a higher-order opto-magnetic effect (ICME).
- The quadratic dependence of the F sin 6α component on pump fluence was used to verify the second-order nature of the ICME.
Commercial Applications
Section titled âCommercial Applicationsâ- Next-Generation Quantum Sensing:
- Development of quantum magnetometers capable of measuring magnetic fields and spin dynamics at the sub-picosecond time scale, critical for studying ultrafast phenomena in materials.
- Spintronics and Magnetic Storage:
- High-speed, non-destructive characterization of magnetic domain wall dynamics and magnetization reversal processes in advanced memory (e.g., MRAM) and spintronic devices.
- Mapping transient magnetic fields generated by current pulses in nanoscale circuits.
- High-Frequency Electronics and Power Devices:
- All-optical measurement of electric currents and fields in high-speed electronic circuits and power devices, providing diagnostics without requiring electrical contacts.
- Hybrid Sensing Platforms:
- Integration of this ultrafast opto-magnetic readout technique with Scanning Probe Microscopy (SPM) to achieve simultaneous nanometer spatial resolution and sub-picosecond temporal resolution for comprehensive material characterization.
- Fundamental Materials Science:
- Investigating coherent spin ensemble dynamics and impulsive stimulated Raman scattering processes in diamond and other wide-bandgap semiconductors.
View Original Abstract
The current generation of quantum sensing technologies using color centers in diamond crystals is primarily based on the principle that the resonant microwave frequency of the luminescence between quantum levels of the nitrogen-vacancy (NV) center varies with temperature and electric and magnetic fields. This principle enables us to measure, for instance, magnetic and electric fields, as well as local temperature with nanometer resolution in conjunction with a scanning probe microscope (SPM). However, the time resolution of conventional quantum sensing technologies has been limited to microseconds due to the limited luminescence lifetime. Here, we investigate ultrafast opto-magnetic effects in diamond crystals containing NV centers to improve the time resolution of quantum sensing to sub-picosecond time scales. The spin ensemble from diamond NV centers induces an inverse Cotton-Mouton effect (ICME) in the form of a sub-picosecond optical response in a femtosecond pump-probe measurement. The helicity and quadratic power dependence of the ICME can be interpreted as a second-order opto-magnetic effect in which ensembles of NV electron spins act as a source for the ICME. The results provide fundamental guidelines for enabling high-resolution spatial-time quantum sensing technologies when combined with SPM techniques.