Single spin optical read-out in CdTe/ZnTe quantum dot studied by photon correlation spectroscopy

TL;DR

This study demonstrates near-perfect all-optical read-out of single electron spins in CdTe/ZnTe quantum dots by polarization correlation spectroscopy, revealing spin memory effects and relaxation times under magnetic fields.

Contribution

It introduces a method for high-efficiency optical spin read-out in quantum dots and quantitatively models spin dynamics with a simple rate equation approach.

Findings

Achieved 68% all-optical spin read-out efficiency.

Observed spin memory effects lasting tens of nanoseconds.

Measured exciton spin relaxation times from 3.4 ns to 16 ns with magnetic field.

Abstract

Spin dynamics of a single electron and an exciton confined in CdTe/ZnTe quantum dot is investigated by polarization-resolved correlation spectroscopy. Spin memory effects extending over at least a few tens of nanoseconds have been directly observed in magnetic field and described quantitatively in terms of a simple rate equation model. We demonstrate an effective (68%) all-optical read-out of the single carrier spin state through probing the degree of circular polarization of exciton emission after capture of an oppositely charged carrier. The perturbation introduced by the pulsed optical excitation serving to study the spin dynamics has been found to be the main source of the polarization loss in the read-out process. In the limit of low laser power the read-out efficiency extrapolates to a value close to 100%. The measurements allowed us as well to determine neutral exciton spin relaxation time ranging from 3.4 +/- 0.1 ns at B = 0 T to 16 +/- 3 ns at B = 5 T.