Quantum Engineering With Hybrid Magnonic Systems and Materials (Invited Paper)

At a Glance

Metadata	Details
Publication Date	2021-01-01
Journal	IEEE Transactions on Quantum Engineering
Authors	D. D. Awschalom, Chunhui Du, Rui He, F. Joseph Heremans, Axel Hoffmann
Institutions	University of Michigan, Texas Tech University
Citations	127
Analysis	Full AI Review Included

Technical Documentation & Analysis: Quantum Engineering with Hybrid Magnonic Systems

Document Title: MPCVD Diamond Platforms for Hybrid Magnonics and NV-Center Quantum Systems Source Paper: Quantum Engineering With Hybrid Magnonic Systems and Materials (Invited Paper) Target Audience: Quantum Engineers, Spintronics Researchers, Materials Scientists

Executive Summary

This review highlights the critical role of hybrid magnonic systems, particularly those integrating solid-state qubits like the Nitrogen-Vacancy (NV^-) center in diamond, for next-generation quantum technologies. 6CCVD provides the foundational material platforms necessary to realize these advanced systems.

Core Application: Hybrid magnonics enables coherent quantum information transfer and sensing by coupling magnons (spin waves) with photons, phonons, and solid-state qubits (NV centers).
Diamond as the Qubit Host: High-purity Single Crystal Diamond (SCD) is identified as the premier host material for NV centers, offering long coherence times and an optical interface for spin initialization and readout.
Key Requirement: Successful integration demands ultra-low-loss SCD substrates, precise nanoscale proximity control (e.g., NV-to-YIG distance ~100 nm), and custom thin-film metalization (Pt, Au, Ti).
6CCVD Value Proposition: We supply the required high-quality SCD substrates (Ra < 1 nm) and offer comprehensive customization, including precise thickness control (0.1 µm to 500 µm) and in-house metalization (Au, Pt, Ti, W) for direct device fabrication.
Scaling Potential: The use of diamond platforms supports the development of scalable, chip-scale quantum interconnects and sensors, moving beyond macroscopic devices.

Technical Specifications

The research relies on materials and operational parameters that demand extreme precision and quality, particularly concerning the diamond host and coupling mechanisms.

Parameter	Value	Unit	Context / Requirement
NV Ground State Splitting (D)	2.87	GHz	Zero-field splitting of the NV^- ms = ±1 states.
Magnon Quality Factor (Q)	~10⁵	Dimensionless	Target for long-coherence magnon-photon interaction.
Magnon Frequency Range	Sub-GHz to THz	GHz/THz	Compatibility with existing qubit technologies (GHz) and novel AFM systems (THz).
NV-to-YIG Distance	~100	nm	Required for maximizing coupling strength in sensing experiments.
SCD Substrate Thickness (6CCVD Cap.)	0.1 - 500	µm	SCD thickness range available for NV integration and nanobeam fabrication.
PCD Wafer Diameter (6CCVD Cap.)	Up to 125	mm	Maximum size for scalable, chip-scale integration.
SCD Surface Roughness (Ra)	< 1	nm	Ultra-smooth surface required for high-quality thin-film deposition (YIG, Py) and NV proximity.
Cryogenic Operation Temperature	1.5	K	Temperature used for strong magnon-photon coupling experiments.
Spin Chemical Potential (µ)	~0.005	µs^-1	Measured NV relaxation rate change (ΔΓ) under spin Hall current injection.

Key Methodologies

The paper reviews several advanced methodologies crucial for developing and characterizing hybrid magnonic systems, many of which rely on high-quality diamond substrates.

Optically Detected Magnetic Resonance (ODMR): Used for noninvasive initialization and readout of the NV center spin state, providing a sensitive probe for proximal magnetic fields and magnon dynamics.
Microwave Engineering and Superconducting Resonators: Utilization of coplanar waveguide (CPW) and lumped element resonators (LER) to achieve strong coupling between microwave photons and magnons (e.g., in Py or YIG thin films) at cryogenic temperatures (1.5 K).
Spin-Wave Mediated Coherent Control: Demonstration of long-range coherent driving of NV centers (up to several hundred µm) mediated by magnetostatic surface spin-wave modes in YIG films.
Spin Hall Effect (SHE) Injection: Electrical generation of spin chemical potential (µ) in magnetic insulators (YIG) by applying a charge current (J_c) through an adjacent heavy metal strip (Pt), enabling tunable magnon density.
Advanced Fabrication Techniques: Use of pulsed laser deposition, lift-off, and focused ion beam etching to create freestanding YIG microbeams and diamond nanobeams, enabling nanoscale control over device geometry and coupling strength.
Magneto-Raman Spectroscopy: Employed for characterizing novel magnetic excitations (magnons) in 2-D van der Waals (vdW) magnets and spin-orbit-coupled (SOC) materials, offering high energy and spatial resolution.

6CCVD Solutions & Capabilities

6CCVD is uniquely positioned to supply the high-specification materials and custom fabrication services required to advance research in hybrid magnonics and solid-state quantum systems, particularly those utilizing NV centers in diamond.

Applicable Materials

To replicate and extend the NV-magnon coupling experiments detailed in Section IV, researchers require diamond with exceptional purity and surface quality.

Optical Grade Single Crystal Diamond (SCD): Essential for hosting high-coherence NV centers. Our SCD material offers extremely low nitrogen content, minimizing parasitic defects and ensuring the long spin coherence times (T₂) necessary for quantum operations.
High-Purity SCD Substrates: Available in thicknesses from 0.1 µm up to 500 µm and substrates up to 10 mm thick, providing robust platforms for complex device integration (e.g., YIG/Pt/Au stacks on diamond).
Boron-Doped Diamond (BDD): For applications requiring conductive diamond components (e.g., electrodes or integrated heaters), 6CCVD offers BDD films with tunable doping levels.

Customization Potential

The integration of NV centers with magnetic thin films (YIG, Py) and metallic striplines (Pt, Au) necessitates precise material engineering, a core strength of 6CCVD.

Service	Research Requirement from Paper	6CCVD Capability
Custom Metalization	Pt (10 nm thick) and Au (600 nm thick) striplines for SHE injection and microwave control.	In-house deposition of Au, Pt, Pd, Ti, W, and Cu films, allowing for the precise fabrication of striplines and antennae directly onto the diamond substrate.
Surface Preparation	Ultra-smooth surfaces for nanoscale proximity (NV-to-YIG distance ~100 nm).	Polishing to Ra < 1 nm (SCD) and Ra < 5 nm (PCD), ensuring optimal interface quality for thin-film growth and minimal magnetic noise.
Custom Dimensions	Fabrication of diamond nanobeams and microstructures.	Precision laser cutting and shaping of SCD and PCD wafers up to 125 mm diameter, enabling the creation of custom geometries for LER coupling or mechanical resonators.
Thickness Control	SCD films for nanobeam fabrication or thin-film growth.	SCD and PCD films available with thickness control from 0.1 µm to 500 µm, supporting both thin-film device layers and robust substrates.

Engineering Support

6CCVD’s in-house PhD team specializes in the material science of diamond quantum platforms. We offer authoritative support for optimizing material selection and integration strategies for complex hybrid systems.

NV Integration Optimization: Assistance with selecting the optimal SCD grade and orientation for maximizing NV center yield, coherence, and coupling efficiency with adjacent magnonic materials.
Thermal Management: Consultation on using diamond’s superior thermal properties to manage heat dissipation in high-power microwave or optical drive experiments, especially critical for cryogenic operation (1.5 K).
Heterogeneous Integration: Guidance on preparing diamond surfaces for the epitaxial or flip-chip integration of magnetic materials (YIG, Py) and superconducting circuits (NbN, Nb).

Call to Action: For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

Quantum technology has made tremendous strides over the past two decades with remarkable advances in materials engineering, circuit design, and dynamic operation. In particular, the integration of different quantum modules has benefited from hybrid quantum systems, which provide an important pathway for harnessing different natural advantages of complementary quantum systems and for engineering new functionalities. This review article focuses on the current frontiers with respect to utilizing magnons for novel quantum functionalities. Magnons are the fundamental excitations of magnetically ordered solid-state materials and provide great tunability and flexibility for interacting with various quantum modules for integration in diverse quantum systems. The concomitant-rich variety of physics and material selection enable exploration of novel quantum phenomena in materials science and engineering. In addition, the ease of generating strong coupling with other excitations makes hybrid magnonics a unique platform for quantum engineering. We start our discussion with circuit-based hybrid magnonic systems, which are coupled with microwave photons and acoustic phonons. Subsequently, we focus on the recent progress of magnon-magnon coupling within confined magnetic systems. Next, we highlight new opportunities for understanding the interactions between magnons and nitrogen-vacancy centers for quantum sensing and implementing quantum interconnects. Lastly, we focus on the spin excitations and magnon spectra of novel quantum materials investigated with advanced optical characterization.

Tech Support

Original Source

DOI: https://doi.org/10.1109/tqe.2021.3057799