Quantum Engineering With Hybrid Magnonic Systems and Materials (Invited Paper)
At a Glance
Section titled “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 Waterloo, University of Illinois Urbana-Champaign |
| Citations | 127 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled “Executive Summary”- Universal Quantum Transduction: Magnons are established as highly tunable, flexible mediators for coherent coupling between disparate quantum systems, including microwave photons, acoustic phonons, and solid-state spin qubits (e.g., NV centers).
- Strong Coupling Regimes Achieved: The strong coupling regime has been experimentally demonstrated across multiple hybrid platforms, including magnon-photon systems (up to 171 MHz coupling) and magnon-phonon systems (cooperativity > 7.8).
- Dynamic Control for Quantum Operations: Rapid, dynamic tuning of the magnon resonance frequency via bias magnetic fields enables coherent quantum operations, such as SWAP and SPLIT, essential for quantum information transfer and processing.
- Engineered Magnon-Magnon Interactions: Coupling between acoustic and optical magnon modes is controlled in layered magnetic systems (Synthetic Antiferromagnets and 2D vdW magnets like CrCl3) by manipulating external field orientation or material damping.
- Nanoscale Quantum Sensing: Solid-state defects (NV centers in diamond) are utilized as ultrasensitive, nanoscale probes to detect noncoherent thermal magnons, measure spin chemical potential, and study spin-wave dispersion in magnetic insulators (YIG).
- Exploration of Novel Materials: Advanced optical spectroscopy techniques (Magneto-Raman, Sagnac MOKE) are driving the discovery and characterization of high-energy magnonic excitations in 2D vdW magnets and chirality-induced spin selectivity (CISS) effects in hybrid organic-inorganic perovskites.
Technical Specifications
Section titled “Technical Specifications”| Parameter | Value | Unit | Context |
|---|---|---|---|
| Magnon-Photon Coupling Strength (g/2π) | 171 | MHz | Achieved in 2000 µm x 8 µm x 50 nm Py stripe on superconducting resonator. |
| Magnon-Phonon Coupling Strength (g/2π) | 200 | MHz | Measured in surface patterned FeGaB/LiNbO3 system. |
| Magnon Decoherence Rate (Γm/2π) | 170 | MHz | Measured in FeGaB/LiNbO3 system. |
| Phonon Decoherence Rate (Γp/2π) | 30 | MHz | Measured in FeGaB/LiNbO3 system. |
| Magnon-Phonon Cooperativity | > 7.8 | Dimensionless | Achieved in FeGaB/LiNbO3 system. |
| YIG Thin Film Damping (α) | ~10-4 | Dimensionless | Required for long magnon spin diffusion length. |
| NV Center Ground State Splitting (D) | 2.87 | GHz | Diamond NV center zero-field splitting. |
| NV Center Gyromagnetic Ratio (γ) | 28 | MHz/mT | Used for Zeeman splitting calculations. |
| NV Center Field Sensitivity | Down to 10-9 | T | Sensitivity for local static and oscillating magnetic fields. |
| CrCl3 Neél Temperature (TN) | ≈ 14 | K | 2D vdW antiferromagnet. |
| CrCl3 Interlayer Exchange Field (μ0HE) | 101 | mT | Derived from LLG fitting of mode dispersion. |
| Magnon-Magnon Coupling (CrCl3) | ≈ 0.8 | GHz | Extracted coupling gap at field angle ψ = 55°. |
| CISS-Induced Kerr Rotation (ΔθKerr) | ≈ 1.0 | µrad | Light-driven magnetism in Chiral-HMH/NiFe bilayer. |
| CISS-Induced Effective Magnetic Field | ≈ ±2 | mT | Generated at the NiFe interface by photoexcitation. |
| Sagnac MOKE Resolution | 50 | nanoradians | Ultrasensitive detection tool for CISS effects. |
Key Methodologies
Section titled “Key Methodologies”- Circuit Quantum Electrodynamics (cQED) Integration: Fabrication of magnetic thin films (Permalloy, YIG) directly onto or coupled via flip-chip techniques to coplanar superconducting resonators (CPW) to achieve strong magnon-photon coupling in the GHz regime.
- Magnetoelastic Hybridization via Acoustic Waves: Utilizing piezoelectric substrates (LiNbO3) with interdigitated transducers (IDTs) to generate Surface Acoustic Waves (SAWs) or Bulk Acoustic Waves (BAWs), which are then coupled to ferromagnetic films (Ni, FeGaB) to study hybrid magnon-polaron modes.
- Dynamic Magnetic Field Control: Implementing linearly ramped or pulsed bias magnetic fields to rapidly tune the magnon resonance frequency, enabling adiabatic passage through the resonance point for coherent quantum operations (SWAP, SPLIT) on hybrid magnon-photon systems.
- Nanoscale Fabrication of YIG Structures: Developing specialized techniques, including pulsed laser deposition and focused ion beam (FIB) etching, to create single-crystal, free-standing YIG microbeams and nanoresonators for enhanced magnetomechanical coupling.
- NV Center Quantum Relaxometry: Employing a three-level model and stroboscopic measurement sequence (green laser initialization, microwave π pulse, photoluminescence readout) to quantitatively measure the longitudinal spin relaxation rate (Γ1) of NV centers, thereby mapping local magnon density and spin chemical potential.
- Symmetry-Resolved Magneto-Raman Spectroscopy: Using high-sensitivity optical scattering techniques, often at cryogenic temperatures (10 K), to probe zone-center magnetic excitations (single and two-magnons) and phonons coupled to static magnetic order in 2D vdW magnets (CrI3) and SOC iridates (Sr3Ir2O7).
- Ultrasensitive Magneto-Optical Kerr Effect (MOKE): Utilizing a modified fiber Sagnac interferometer to achieve nanoradian resolution MOKE measurements, enabling the detection of subtle, light-driven magnetization changes induced by the Chirality-Induced Spin Selectivity (CISS) effect in hybrid organic-inorganic semiconductor interfaces.
Commercial Applications
Section titled “Commercial Applications”-
Quantum Information and Communication:
- Quantum Transduction: Magnons serving as efficient, tunable interfaces to convert quantum information between microwave (qubit) and optical (long-distance fiber) frequencies.
- On-Chip Quantum Networks: Building scalable, integrated architectures for quantum computing and communication using hybrid magnonic circuits.
- Quantum Memories: Utilizing long-coherence phonon modes hybridized with magnons for robust, solid-state quantum storage.
-
Advanced Sensing and Metrology:
- Nanoscale Magnetic Sensing: Employing NV centers for high-resolution, noninvasive probing of magnetic domains, spin transport, and dynamic behaviors in spintronic devices and emergent quantum materials.
- High-Frequency ESR/NMR: Achieving quantum-limited sensitivity in Electron Spin Resonance (ESR) and Nuclear Magnetic Resonance (NMR) using hybrid magnonic systems.
-
RF and Microwave Technology:
- Nonreciprocal Devices: Designing compact, high-efficiency circulators and isolators by leveraging the broken time-reversal symmetry inherent in magnon-phonon coupled systems.
- Miniaturized Components: Utilizing the short wavelength of magnons to realize highly miniaturized microwave components for integrated RF systems.
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Spintronics and Energy-Efficient Computing:
- Energy-Efficient Neuromorphic Computing: Exploring amorphous FeGa/FeCo alloys for strong magnetoelastic coupling combined with low damping, beneficial for energy-efficient neuromorphic architectures.
- Optomagnetism: Developing novel devices based on Chiral-HMHs that enable mutual interconversion between photons, charges, and spins, leading to new solution-processed spintronic technologies.
- High-Speed Data Processing: Utilizing synthetic antiferromagnets (SAFs) for high-speed, tunable spin-wave states relevant for advanced spintronic memory and logic.
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.