Nanoscale stray fields from micromagnets for optimal spin qubit architecture

Abstract

On-chip micromagnets generate local magnetic-field asymmetries, enabling electrical control of spin qubits via electric dipole spin resonance and their integration into circuit quantum electrodynamics (QED) architectures. Accurate prediction of spin-qubit performance requires modeling micromagnet stray fields beyond the saturated-magnet approximation, accounting for nonuniform magnetization. Here, we combine thin-film characterization of Co, Co/Ta multilayers, and CoFe films with nanoscale stray-field measurements using NV-center magnetometry in the unsaturated regime to establish a reliable micromagnetic simulation framework. We show that CoFe micromagnets generate antisymmetric fields in double quantum-dot geometries exceeding +/- 100mT, owing to their high saturation magnetization and favorable magnetocrystalline anisotropy. For spin qubits coupled to microwave resonators, the predicted spin-photon coupling reaches $\left|g_s/g_c\right|\approx 0.5$, where $g_c$ denotes the charge-photon coupling strength of the underlying charge qubit, highlighting the potential for high-fidelity operations in circuit QED architectures.

16 pages, 5 figures

References in corpus (30)

• The design and verification of Mumax3
• Magnetometry with nitrogen-vacancy defects in diamond
• A >99.9%-fidelity quantum-dot spin qubit with coherence limited by charge noise
• Semiconductor Spin Qubits
• Electrically driven single electron spin resonance in a slanting Zeeman field
• A Coherent Spin-Photon Interface in Silicon
• Universal control of a six-qubit quantum processor in silicon
• Strong spin-photon coupling in silicon
• Dissipation and Ultrastrong Coupling in Circuit QED
• Coherent single electron spin control in a slanting Zeeman field
• Scanned probe imaging of nanoscale magnetism at cryogenic temperatures with a single-spin quantum sensor
• Long-Range Microwave Mediated Interactions Between Electron Spins
• Stray-field imaging of magnetic vortices with a single diamond spin
• Strong coupling of a spin qubit to a superconducting stripline cavity
• Strong coupling between a photon and a hole spin in silicon
• Robust micro-magnet design for fast electrical manipulations of single spins in quantum dots
• Optimized cavity-mediated dispersive two-qubit gates between spin qubits
• Micro-magnets for coherent control of spin-charge qubit in lateral quantum dots
• Coupling a single electron spin to a microwave resonator: Controlling transverse and longitudinal couplings
• Tunable magnetic textures in spin valves: From spintronics to Majorana bound states
• Coherent Manipulation of Individual Electron Spin in a Double Quantum Dot Integrated with a Micro-Magnet
• Two-qubit logic between distant spins in silicon
• Highly coherent spin states in carbon nanotubes coupled to cavity photons
• Low dephasing and robust micromagnet designs for silicon spin qubits
• Designing Nanomagnet Arrays for Topological Nanowires in Si
• Optimized micromagnet geometries for Majorana zero modes in low g-factor materials
• Integrating micromagnets and hybrid nanowires for topological quantum computing
• Majorana bound states in nanowire-superconductor hybrid systems in periodic magnetic fields
• Optimal design of nanomagnets for on-chip field gradients
• Synthetic spin-orbit coupling in superconductor-semiconductor hybrid nanowires with micromagnet arrays