Strong coupling between a single nitrogen-vacancy spin and the rotational mode of diamonds levitating in an ion trap
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2017-12-07 |
| Journal | Physical review. A/Physical review, A |
| Authors | Tom Delord, L. Nicolas, Yannick Chassagneux, G. HĂ©tet |
| Institutions | Université Paris Sciences et Lettres, Sorbonne Université |
| Citations | 47 |
| Analysis | Full AI Review Included |
Technical Analysis and Documentation: NV Spin-Rotational Coupling in Levitated Diamonds
Section titled âTechnical Analysis and Documentation: NV Spin-Rotational Coupling in Levitated Diamondsâ6CCVD Ref: Quantum Opto-Mechanics (QOM) / NV Center Systems
Executive Summary
Section titled âExecutive SummaryâThis research proposes a pioneering scheme to achieve strong, coherent coupling between a single Nitrogen Vacancy (NV) electronic spin and the rotational mechanical mode of levitating nanodiamonds (NDs) in a Paul ion trap. This method circumvents significant difficulties associated with traditional opto-mechanics, such as required milliKelvin cooling and mechanical clamping structures, positioning 6CCVDâs advanced diamond materials at the forefront of quantum macroscopic control.
- Core Achievement: Demonstrated theoretical pathway to strong coupling ($\Lambda_{\phi}$ up to 60 kHz) using weak homogeneous magnetic fields (~30 mT) coupled with strong microwave driving ($\Omega_R$ up to 1 GHz).
- Key Innovation: Coupling utilizes the rotational degree of freedom of charged, aspherical nanodiamonds (ellipsoidal/composite shapes) stabilized in a Paul trap, dramatically increasing the trapping frequency and coupling rate relative to center-of-mass modes.
- Material Necessity: Achieving the required strong coupling condition mandates ultra-low decoherence rates, specifically long $T_2$ times (target > 150 ”s, ideally 1.8 ms), necessitating high-purity, isotopically engineered 12C MPCVD diamond precursor material.
- Geometry Dependence: Coupling strength is critically dependent on particle shape (aspect ratio $a/b = 2.5$) and size (down to 20 nm radius), requiring advanced micro/nanofabrication capabilities from high-quality SCD wafers.
- Application: This platform is critical for realizing efficient quantum control of macroscopic oscillators and building blocks for future quantum technologies, including entanglement of spins with millions of atoms (Schrödinger cat states).
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Material Precursor | MPCVD Diamond (SCD) | N/A | Required for low decoherence / high purity 12C |
| Particle Geometry | Prolate/Oblate Ellipsoid, Composite | N/A | Required for rotational confinement asymmetry |
| Minimum Particle Radius ($b$) | 20 | nm | Used to achieve highest rotational frequency (5 MHz) |
| Aspect Ratio ($a/b$) | 2.5 | N/A | Optimized asymmetry for confinement |
| NV Center Depth (Target) | 5 | nm | Optimized for shallow spin coupling/readout |
| Maximum B-Field (Transverse) | ~30 | mT | Technical constraint for maintaining spin-phonon resonance |
| Maximum Rabi Frequency ($\Omega$R) | 1000 (1) | MHz (GHz) | Technical maximum bond for microwave driving |
| Required T2 Coherence | > 150 | ”s | Minimum for 20 nm particle strong coupling |
| Bulk T2 Coherence (12C) | ~1.8 | ms | Achievable with isotopically enriched 6CCVD SCD |
| Strong Coupling Rate ($\Lambda$$\phi$) | 35 to 60 | kHz | Achieved for 20 nm radius, $\Omega$R=500 MHz |
| Rotational Frequency ($\omega$$\phi$/2$\pi$) | 0.5 to 5.0 | MHz | Dependent on particle size (80 nm to 20 nm) |
| Paul Trap AC Voltage ($V_{ac}$) | 5000 | V | Peak-to-peak voltage applied between electrodes |
| Required Surface Charge ($Q_{tot}$) | > 60 | Elementary charges | Needed for 80 nm particle, 0.5 MHz trapping |
Key Methodologies
Section titled âKey MethodologiesâThe experiment proposes leveraging the material properties of diamond and the controlled environment of a Paul trap to achieve coherent quantum interaction:
- Material and Defect Engineering: Use high-purity, low-decoherence diamond (ideally isotopically engineered 12C) to host deeply stable NV centers, ensuring spin coherence times ($T_2$) are long enough (up to 1.8 ms) to meet the strong coupling condition ($\Lambda_{\phi} T_2 > 1$).
- Geometry Optimization: Utilize asymmetric particle shapes (prolate/oblate ellipsoids or thin composite disks) with an aspect ratio of $a/b = 2.5$ to increase the rotational confinement frequency ($\omega_{\phi}$) and reduce the particleâs moment of inertia ($I_y$).
- Rotational Confinement: Charged nanodiamonds are levitated in a Paul ion trap. The electric potential ($V_{E}$) and particle asymmetry induce rotational confinement, stabilizing the angle ($\phi$) for the rotational degree of freedom.
- Spin-Rotational Coupling: Introduce a weak, homogeneous transverse magnetic field ($B$ up to ~30 mT) and strong microwave driving ($\Omega_R$ up to 1 GHz). The rotation of the NV center relative to the B-field modulates the NV spin energy, establishing coupling between the spin and the mechanical rotational mode.
- Resonance Matching: Tune the microwave frequency to resonate with the $|g\rangle$ to $|d\rangle$ spin transition ($\omega \sim \omega_{dg}$) while ensuring the spin-phonon resonance condition ($|\omega_{eâ} - \omega_{+}| = \omega_{\phi}$) is met, maximizing the effective coupling rate ($\Lambda_{\phi}$).
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThis demanding quantum opto-mechanics research relies critically on superior diamond material quality and precise custom fabrication, areas where 6CCVD excels.
Applicable Materials
Section titled âApplicable MaterialsâTo replicate and extend this high-coherence levitated quantum system, the following 6CCVD materials are required:
| Material Specification | Application in Research | 6CCVD Capability |
|---|---|---|
| High-Purity Single Crystal Diamond (SCD) | Precursor material for nanodiamond synthesis; ensures long $T_2$ times. | We provide large-area, high-quality SCD up to 10 mm substrates for demanding quantum applications. |
| Isotopically Engineered Diamond | Critical for minimizing 13C nuclear spin bath decoherence, essential for achieving $T_2$ times > 1 ms. | We specialize in tailored gas mixtures for MPCVD growth to control isotopic composition, maximizing spin coherence. |
| SCD Wafers for RIE/Fabrication | Source material from which the required aspherical nanodiamonds (ellipsoids, nano-pillars) are etched/derived. | Plates/wafers available in sizes up to 125mm (PCD) or custom SCD dimensions suitable for Reactive Ion Etching (RIE) processes referenced (e.g., [34]). |
Customization Potential
Section titled âCustomization PotentialâThe experimental success hinges on precise geometric control (nanoparticle shape and aspect ratio) and, potentially, the integration of control electronics. 6CCVD offers end-to-end solutions for material preparation and device integration:
- Precision Fabrication: The requirement for custom geometries (prolate/oblate ellipsoids, thin disks, nano-pillars) necessitates advanced patterning and laser cutting. 6CCVD offers custom laser cutting and wafer dicing to prepare the precursor SCD material for subsequent RIE processes used to form the asymmetric particles.
- High-Quality Polishing: While the final particles are nanoscale, the quality of the starting SCD wafer is paramount. 6CCVD guarantees ultra-smooth polishing (Ra < 1 nm for SCD), ensuring optimal surface quality before nanodiamond synthesis, mitigating surface charge fluctuations and reducing electric field noise that degrades NV spin performance.
- Custom Metalization Schemes: Although the levitated diamond uses surface charging, future extensions of this research may require contact pads for electrical control or integration into resonant microwave structures. 6CCVD offers in-house metalization services, including: Au, Pt, Pd, Ti, W, and Cu deposition, tailored to client specifications (e.g., Ti/Pt/Au stacks).
Engineering Support
Section titled âEngineering SupportâThe optimization of the strong coupling regime requires balancing intrinsic diamond parameters (T2, NV depth) with extrinsic trap parameters (geometry, $\Omega_R$, B-field). Our expert engineering team is prepared to assist researchers:
- 6CCVDâs in-house PhD team provides consultative support for material selection, ensuring the chosen SCD substrate maximizes the achievable $T_2$ coherence time necessary for successful Quantum Opto-Mechanical coupling projects.
- We offer technical guidance on selecting optimal thickness (SCD from 0.1 ”m to 500 ”m) and orientation for NV center generation, whether the goal is ultra-shallow (5 nm) or deeper NV placement (>100 nm).
- We provide flexible Global Shipping (DDU default, DDP available), ensuring sensitive research materials reach labs worldwide efficiently and securely.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
A scheme for strong coupling between a single atomic spin and the rotational mode of levitating nanoparticles is proposed. The idea is based on spin read-out of NV centers embedded in aspherical nanodiamonds levitating in an ion trap. We show that the asymmetry of the diamond induces a rotational confinement in the ion trap. Using a weak homogeneous magnetic field and a strong microwave driving we then demonstrate that the spin of the NV center can be strongly coupled to the rotational motion of the diamond.