Optically detected magnetic resonance with an open source platform
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2023-10-09 |
| Journal | SciPost Physics Core |
| Authors | Hossein Babashah, Hoda Shirzad, Elena Losero, V. Goblot, Christophe Galland |
| Institutions | Ăcole Polytechnique FĂ©dĂ©rale de Lausanne |
| Citations | 15 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: ODMR Platform Development
Section titled âTechnical Documentation & Analysis: ODMR Platform DevelopmentâExecutive Summary
Section titled âExecutive SummaryâThis document analyzes the research paper âOptically detected magnetic resonance with an open source platform,â focusing on the requirements for high-performance quantum sensing materials, specifically Nitrogen-Vacancy (NV) centers in diamond.
- Core Application: The research establishes a robust, open-source platform (Qudi) for Optically Detected Magnetic Resonance (ODMR), primarily utilizing NV centers in diamond for quantum sensing and metrology.
- Material Requirement: High-purity Single Crystal Diamond (SCD) is essential to achieve the long spin coherence times ($T_1$, $T_2$) necessary for advanced pulsed ODMR sequences (Rabi, Ramsey, Hahn Echo).
- Critical Material Parameters: The system relies on diamond substrates optimized for NV center creation, exhibiting low strain and minimal background defects (like neutral NVO).
- 6CCVD Value Proposition: 6CCVD provides the necessary high-quality MPCVD SCD substrates (Ra < 1 nm polish) and customization services (metalization for integrated MW antennas) required to replicate and advance the described room-temperature quantum experiments.
- Customization Potential: We offer custom dimensions (up to 125 mm PCD) and precise thickness control (0.1 ”m to 500 ”m SCD) to optimize both confocal microscopy and integrated microwave circuit design.
- Engineering Support: Our in-house PhD team specializes in material selection and preparation for NV center creation, ensuring optimal performance for quantum applications.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points characterize the NV center system and experimental parameters detailed in the paper, focusing on ensemble measurements in bulk diamond.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| ODMR System Host | Diamond | N/A | Negatively charged Nitrogen-Vacancy (NV-) center |
| Zero Field Splitting (D) | 2.87 | GHz | Ground state triplet (3A2) |
| Gyromagnetic Ratio ($\gamma$) | 28 | GHz T-1 | Used for magnetic field sensing |
| Optical Pumping Wavelength | 515 or 532 | nm | Off-resonance (Green) |
| Photoluminescence (PL) Wavelength | 637 | nm | Readout signal (Red) |
| Longitudinal Relaxation Time ($T_1$) | Several | ms | NV ensemble, room temperature |
| Dephasing Time ($T_2^*$) | 0.5 - 1 | ”s | NV ensemble, room temperature |
| Coherence Time ($T_2$) | Few 10s (up to 100) | ”s | NV ensemble, with dynamical decoupling |
| CW ODMR Contrast (Ensemble) | ~1 | % | Typical best contrast reported (Fig 2, Fig 11) |
| Rabi Oscillation Frequency ($\Omega_R/2\pi$) | 1 - 3 | MHz | Dependent on MW power |
| Laser Power (Confocal) | mW | Range | Sufficient to saturate the emitter |
| Optical Pulse Duration (Initialization) | 100 ns to 1 | ”s | Required for maximum spin polarization |
Key Methodologies
Section titled âKey MethodologiesâThe experimental setup and procedures described rely on precise synchronization and control of optical and microwave components, facilitated by the Qudi open-source platform.
- Confocal Photoluminescence (PL) Microscopy:
- Utilizes high Numerical Aperture (NA) objectives (up to 0.9) for diffraction-limited spot size and efficient PL collection.
- Scanning is achieved via piezo-based nanopositioning stages or 2-axis oscillating mirrors.
- PL detection uses either digital photon counters (d-PC) for single emitters or analog photodetectors (a-PD) for large ensembles.
- Microwave (MW) Instrumentation:
- MW signals (GHz range) are generated by tabletop sources (e.g., Rohde & Schwarz) or VCOs, amplified (up to 30 dBm), and delivered via custom antennas (e.g., wire loops, split-ring resonators) integrated near the diamond sample.
- MW pulses are carved out of a Continuous Wave (CW) source using external switches (AOMs or internal generator switches).
- Bias Magnetic Field Application:
- A DC magnetic field is applied (via permanent magnets or Helmholtz coils) to lift degeneracy (Zeeman splitting) and tailor spin eigenstates for optimal sensitivity or cross-relaxation studies.
- Continuous Wave (CW) ODMR:
- Optical emission is recorded while sweeping the MW frequency to observe resonance dips (magnetic resonance spectrum). Optimization requires balancing MW power (to avoid broadening) and laser power (to ensure polarization).
- Pulsed ODMR Sequences:
- Requires synchronization of laser pulses (initialization/readout) and MW pulses ($\pi$ and $\pi/2$ pulses) using a pulse generator and DAQ card.
- Sequences include Relaxometry ($T_1$), Rabi oscillations (pulse calibration), Ramsey ($T_2^*$), and Hahn Echo ($T_2$) for characterizing spin dynamics and sensing external fields.
- Data Acquisition and Synchronization:
- Data is acquired using DAQ cards (analog or digital counting) or oscilloscopes, synchronized via TTL pulses. Advanced methods like time-tagging or NP/PN averaging strategies are employed to maximize signal-to-noise ratio (SNR).
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe successful implementation of advanced ODMR experiments, particularly those requiring long coherence times and integrated microwave delivery, depends critically on the quality and customization of the diamond substrate. 6CCVD is uniquely positioned to supply the necessary materials and engineering services.
Applicable Materials
Section titled âApplicable MaterialsâTo replicate and extend the high-coherence NV ensemble measurements described in the paper, 6CCVD recommends the following materials:
| 6CCVD Material Grade | Description & Application | Key Benefit for ODMR |
|---|---|---|
| Optical Grade SCD | High-purity, low-strain Single Crystal Diamond. Ideal for post-growth NV center creation (via implantation/annealing). | Maximizes $T_1$ and $T_2$ coherence times by minimizing lattice defects and nitrogen background. Essential for high-fidelity quantum experiments. |
| Substrate Grade SCD | Thick SCD substrates (up to 10 mm) for robust mechanical support and thermal management in high-power MW setups. | Provides stable platform for complex confocal and MW antenna integration, mitigating sample heating effects. |
| Polycrystalline Diamond (PCD) | Available in large formats (up to 125 mm diameter) for wide-field imaging applications or large-area sensor arrays. | Cost-effective solution for ensemble measurements where spatial homogeneity over large areas is prioritized over ultimate single-spin coherence. |
| Boron-Doped Diamond (BDD) | Conductive diamond films for electrochemical sensing or integrated ground planes in MW circuits. | Enables advanced applications like photoelectric detection of NV spins [20] or integrated electrical contacts. |
Customization Potential
Section titled âCustomization PotentialâThe paper highlights the need for precise optical alignment (high NA objectives) and integrated MW delivery (antennas). 6CCVDâs customization capabilities directly address these engineering challenges:
- Precision Polishing (Optical Quality): We guarantee surface roughness Ra < 1 nm on SCD wafers, critical for minimizing scattering losses and achieving diffraction-limited focusing using high-NA objectives in confocal setups.
- Custom Dimensions and Thickness: We supply custom plates and wafers up to 125 mm (PCD) and substrates up to 10 mm thick, allowing researchers to design optimal geometries for MW coupling structures (e.g., double split-ring resonators [105]).
- Integrated Metalization Services: The integration of MW antennas (wire loops, striplines) requires precise metal deposition. 6CCVD offers in-house metalization using Au, Pt, Pd, Ti, W, and Cu. This capability is crucial for creating high-performance, low-loss microwave circuits directly on the diamond surface.
- Laser Cutting and Shaping: Custom shapes and precise edge preparation can be provided to fit specific cryo-compatible device footprints (below a few square millimeters) mentioned in the paperâs conclusions.
Engineering Support
Section titled âEngineering SupportâThe optimization of ODMR sensitivity relies heavily on material quality, NV density, and surface termination.
- NV Center Optimization: 6CCVDâs in-house PhD team can consult on material selection and preparation protocols (e.g., high-pressure, high-temperature (HPHT) vs. MPCVD growth, implantation dose, and annealing recipes) to achieve the desired NV concentration and coherence properties for similar Quantum Sensing and Metrology projects.
- Global Logistics: We ensure reliable, global shipping (DDU default, DDP available) to support international research collaborations, such as those described in the paper involving EPFL and other European institutions.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Localized electronic spins in solid-state environments form versatile and robust platforms for quantum sensing, metrology and quantum information processing. With optically detected magnetic resonance (ODMR), it is possible to prepare and readout highly coherent spin systems, up to room temperature, with orders of magnitude enhanced sensitivities and spatial resolutions compared to induction-based techniques, allowing for single spin manipulations. While ODMR was first observed in organic molecules, many other systems have since then been identified. Among them is the nitrogen-vacancy (NV) center in diamond, which is used both as a nanoscale quantum sensor for external fields and as a spin qubit. Other systems permitting ODMR are rare earth ions used as quantum memories and many other color centers trapped in bulk or 2-dimensional host materials. In order to allow the broadest possible community of researchers and engineers to investigate and develop novel ODMR-based materials and applications, we review here the setting up of ODMR experiments using commercially available hardware. We also present in detail the dedicated collaborative open-source interface named Qudi and describe the features we added to speed-up data acquisition, relax instrument requirements and extend its applicability to ensemble measurements. Covering both hardware and software development, this article aims to overview the setting of ODMR experiments and provide an efficient, portable and collaborative interface to implement innovative experiments to optimize the development time of ODMR experiments for scientists of any backgrounds.