Nanoscale spin manipulation with pulsed magnetic gradient fields from a hard disc drive writer

TL;DR

This paper demonstrates the use of hard disk drive (HDD) magnetic writers as nanoscale tools for fast, localized, and spectrally addressable control of individual and multiple electron spins, advancing quantum manipulation techniques.

Contribution

It introduces HDD writers as a novel, efficient method for nanoscale spin manipulation with high gradients and GHz bandwidth, enabling rapid and selective control of spins.

Findings

HDD writers produce tunable magnetic field gradients up to 100 μT/nm.

They enable spectral addressing of individual spins on the nanoscale.

The technique allows fast spin control within nanoseconds, surpassing characteristic spin times.

Abstract

The individual and coherent control of solid-state based electron spins is important covering fields from quantum information processing and quantum metrology to material research and medical imaging. Especially for the control of individual spins in nanoscale networks, the generation of strong, fast and localized magnetic fields is crucial. Highly-engineered devices that demonstrate most of the desired features are found in nanometer size magnetic writers of hard disk drives (HDD). Currently, however, their nanoscale operation, in particular, comes at the cost of excessive magnetic noise. Here, we present HDD writers as a tool for the efficient manipulation of single as well as multiple spins. We show that their tunable gradients of up to 100 {\mu}T/nm can be used to spectrally address individual spins on the nanoscale. Their GHz Bandwidth allows to switch control fields within nanoseconds, faster than characteristic timescales such as Rabi and Larmor periods, spin-spin couplings or optical transitions, thus extending the set of feasible spin manipulations. We used the fields to drive spin transitions through non-adiabatic fast passages or enable the optical readout of spin states in strong misaligned fields. Building on these techniques, we further apply the large magnetic field gradients for microwave selective addressing of single spins and show its use for the nanoscale optical colocalization of two emitters.