Materials Science and Engineering

Coupling spin qubits to dynamic nanoscale magnetic textures for enhanced quantum sensing and control

October 05, 2018

11:30 a.m. ET

Doherty Hall, Room 2210

Jesse Berezovsky, Ph.D.
Associate Professor
Physics Department
Case Western Reserve University

Abstract

As we begin to look at how spin qubits might be integrated into a scalable platform, a fruitful strategy is to engineer the magnetic environment of the spins using micron- or nanometer-scale ferromagnetic (FM) elements, for functionalities such as nanoscale addressability, spin-wave mediated coupling, or enhanced sensing. The promise of these FM/spin interactions brings with it the question of how the coherence properties of the spin will be affected by coupling to these complex mesoscopic systems. To explore the physics of individual spins coupled to a proximal, dynamic ferromagnetic structure, we have studied interactions between individual nitrogen-vacancy (NV) spins and a model FM system – a vortex magnetization state. The complex, yet controllable, spin texture of an FM vortex, formed in a thin disk or nanowire, allows one to study different regimes of interaction with a nearby confined spin. The vortex core produces a large static dipole-like fringe field. The vortex state also displays discrete dynamic modes ranging from several hundred MHz to GHz. By applying an in-plane magnetic field, the position of the vortex core relative to the NV spin can be controlled with nanometer-scale resolution, and time resolution of tens of nanoseconds. As the vortex core is translated into proximity with an NV spin, the fringe field from the core generates a large position-dependent spin splitting, permitting nanoscale spin addressability. We also find that the dynamic interaction of the vortex, NV spins, and the applied microwave field result in amplification of the Rabi transition rate by more than an order of magnitude, opening avenues for enhanced spin control and sensing. Finally, we explore how spin decoherence and relaxation mechanisms are enhanced as the vortex core approaches the NVs, with implications for proposed technology incorporating coherent spins with proximal FM elements.

Bio

Jesse Berezovsky is an Associate Professor in the Physics Department at Case Western Reserve University. His lab designs and creates hybrid systems for controlling coherent quantum spin states in scalable room-temperature platforms. He received his Ph.D. from UC Santa Barbara in 2007. Before joining the CWRU faculty in 2010 he worked as a postdoctoral researcher at Harvard, imaging quantum transport in graphene. Berezovsky has co-authored numerous articles in journals including Science and Nature Physics, as well as a book on the optical properties of electron spins in quantum dots.

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