Long-lived electron spin coherence in CdSe/ZnSSe self-assembled quantum dots

TL;DR

This study demonstrates long-lived electron spin coherence in CdSe/ZnSSe quantum dots, with coherence times up to 13 ns, highlighting potential for quantum information applications.

Contribution

It provides the first detailed measurement of electron spin coherence times in CdSe/ZnSSe quantum dots using time-resolved Kerr rotation.

Findings

Electron spin coherence persists up to 13 ns in n-doped quantum dots.

Dephasing time of 5.6 ns measured at 0.25 T magnetic field.

Hyperfine interaction limits electron spin coherence.

Abstract

The electron spin coherence in n-doped and undoped, self-assembled CdSe/Zn(S,Se) quantum dots has been studied by time-resolved pump-probe Kerr rotation. Long-lived spin coherence persisting up to 13 ns after spin orientation has been found in the n-doped quantum dots, outlasting significantly the lifetimes of charge neutral and negatively charged excitons of 350 - 530 ps. The electron spin dephasing time as long as 5.6 ns has been measured in a magnetic field of 0.25 T. Hyperfine interaction of resident electrons with a nuclear spin fluctuations is suggested as the main limiting factor for the dephasing time. The efficiency of this mechanism in II-VI and III-V quantum dots is analyzed.