Resonant optical control of the spin of a single Cr atom in a quantum dot

TL;DR

This paper demonstrates optical control of a single Cr atom's spin in a quantum dot, including initialization, read-out, and energy tuning via the optical Stark effect, with potential for hybrid spin-mechanical systems.

Contribution

It introduces a method for optically initializing, reading out, and tuning the spin states of a single Cr atom in a quantum dot, advancing quantum control techniques.

Findings

Cr spin can be prepared by resonant optical pumping.

Cr spin relaxation time is approximately 2 microseconds at 5 K.

Optical Stark effect allows independent energy tuning of spin states.

Abstract

A Cr atom in a semiconductor host carries a localized spin with an intrinsic large spin to strain coupling particularly promising for the development of hybrid spin-mechanical systems and coherent mechanical spin driving. We demonstrate here that the spin of an individual Cr atom inserted in a semiconductor quantum dot can be controlled optically. We first show that a Cr spin can be prepared by resonant optical pumping. Monitoring the time dependence of the intensity of the resonant fluorescence of the quantum dot during this process permits to probe the dynamics of the optical initialization of the Cr spin. Using this initialization and read-out technique we measured a Cr spin relaxation time at T=5 K of about 2 microseconds. We finally demonstrate that, under a resonant single mode laser field, the energy of any spin state of an individual Cr atom can be independently tuned by using the optical Stark effect.