Field-based design of a resonant dielectric antenna for coherent spin-photon interfaces
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2021-04-20 |
| Journal | Optics Express |
| Authors | Linsen Li, Hyeongrak Choi, Mikkel Heuck, Dirk Englund |
| Institutions | Massachusetts Institute of Technology |
| Citations | 9 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThis research details a field-based design methodology for a resonant dielectric antenna optimized for coherent spin-photon interfaces, primarily focusing on diamond color centers (NV, SiV, SnV).
- High Interface Efficiency: The optimized holey dielectric antenna achieves a total spin-photon interface efficiency (η) of 81% for NV centers, representing an efficiency improvement of greater than 300 times compared to an unpatterned 150 nm diamond membrane.
- Simultaneous Optimization: The design simultaneously achieves a high Purcell factor (FP) of 420 and a high mode overlap (η2) of 93% to a 0.4 Numerical Aperture (NA) Gaussian far-field mode.
- Design Methodology: A field-based approach combining a Transfer Matrix Model (TMM) with Finite-Difference Time-Domain (FDTD) simulations is used to optimize grating structures for directional coupling and cavity effects for FP enhancement.
- Fabrication Robustness: The design is tolerant to geometry variations (η decreases by less than 13% for ±10% feature variation) and dipole misalignment (η2 changes less than 2% for angle variations less than 45°).
- Noise Mitigation: The structure alleviates surface charge and spin noise by ensuring the closest etched surface is placed greater than 1.4 λ/nd away from the dipole emitter (where nd is the refractive index of diamond).
- Material Versatility: Although optimized for diamond NV centers, the design methodology is applicable to diverse materials and quantum emitters, including Si and GaAs systems.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Maximum Purcell Factor (FP) | 420 | Dimensionless | Optimized holey dielectric antenna |
| Maximum Mode Overlap (η2) | 93 | % | To 0.4 NA Gaussian far field |
| Total Interface Efficiency (η) | 81 | % | Optimized Holey Antenna (NV center, η0=3%) |
| Efficiency Improvement | â„ 300 | Times | Compared to 150 nm unpatterned membrane |
| Target Far Field NA | 0.4 | Dimensionless | Gaussian beam |
| Collection Efficiency (within NA 0.5) | 99 | % | Target Gaussian beam |
| Diamond Membrane Thickness | 150 | nm | Substrate dimension |
| Target Emitter Depth (NV) | 75 | nm | Corresponds to 60 keV implantation |
| Minimum Feature Size (Hole Diameter) | 70 | nm | Holey antenna design |
| NV Radiation Efficiency (η0) | 3 | % | Zero-Phonon Line (ZPL) |
| SnV Radiation Efficiency (η0) | 32 | % | Zero-Phonon Line (ZPL) |
| Robustness (η drop) | < 13 | % | For ±10% geometry variation |
| Robustness (η2 drop) | < 2 | % | For dipole angle variation < 45° |
Key Methodologies
Section titled âKey MethodologiesâThe antenna design relies on a field-based recipe combining grating and cavity principles using a Transfer Matrix Model (TMM) approach informed by FDTD simulations of scattering primitives.
- Field Profile Calculation: Calculate the electric field profile (Re[Ey]) of the y-oriented dipole within the unpatterned 150 nm diamond slab. Define phase fronts (nÏ phase difference) to identify locations for constructive (even fronts) and destructive (odd fronts) interference perturbations.
- Near Field Transformation: Transform the target far field (Etar, 0.4 NA Gaussian) into the target near field (Enear) profile, ensuring azimuthal symmetry.
- Scattering Primitive Simulation: Simulate the in-plane Transverse-Electric (TE) slab mode normally incident on a single perturbation (slot or single period of a hole array) using FDTD. This generates a lookup table containing reflection/transmission coefficients and scattered near field distributions (Es).
- TMM Application and Initial Optimization: Apply the TMM to calculate the total scattered near field by coherently summing contributions from multiple scattering layers using the lookup table. Optimize the initial guess structure (perturbations placed at even phase fronts) by maximizing the mode overlap (η2) between Etar and Es.
- 3D FDTD Optimization: Curve each perturbation layer to match the dipole emission phase fronts and add a bottom reflector (at z = -Zmin). Apply gradient descent optimization using 3D FDTD simulations to maximize the total interface efficiency (η).
- Purcell Factor Enhancement: Introduce destructive interference slots (located at odd dipole field phase fronts, e.g., 3, 5, 7) into the initial guess structure (Step 4) and repeat the 3D FDTD optimization (Step 5) to maximize the Purcell factor (FP).
Commercial Applications
Section titled âCommercial ApplicationsâThe development of highly efficient and robust spin-photon interfaces is critical for scaling quantum technologies.
- Quantum Networking: Enables efficient free-space interfaces for closely packed arrays of quantum memories, crucial for building multiplexed quantum repeaters and long-distance quantum communication links.
- Quantum Computing: Supports the development of modular quantum computers and spin-based fault-tolerant quantum computers by providing high-fidelity interfaces between solid-state qubits and propagating photons.
- Quantum Sensing: Applicable in arrayed quantum sensors, allowing for efficient collection and readout from multiple emitters simultaneously, enhancing sensitivity and spatial resolution.
- Fundamental Photonics: Useful for boson sampling experiments requiring high-brightness, indistinguishable photon sources.
- Solid-State Emitter Technology: The design methodology is transferable to other solid-state quantum emitter systems (e.g., SiV, SnV, GaAs quantum dots) requiring high FP and directional emission.
View Original Abstract
We propose a field-based design for dielectric antennas to interface diamond color centers in dielectric membranes with a Gaussian propagating far field. This antenna design enables an efficient spin-photon interface with a Purcell factor exceeding 400 and a 93% mode overlap to a 0.4 numerical aperture far-field Gaussian mode. The antenna design with the back reflector is robust to fabrication imperfections, such as variations in the dimensions of the dielectric perturbations and the emitter dipole location. The field-based dielectric antenna design provides an efficient free-space interface for closely packed arrays of quantum memories for multiplexed quantum repeaters, arrayed quantum sensors, and modular quantum computers.