Nuclear frequency focusing in periodically pulsed semiconductor quantum dots described by infinite classical central spin models

TL;DR

This paper investigates how repeated optical pulses and magnetic fields can synchronize nuclear spins in quantum dots, reducing electron spin decoherence, using a classical model to analyze nuclear frequency focusing.

Contribution

It introduces an efficient classical approach to analyze nuclear frequency focusing in quantum dots under periodic pulsing and magnetic fields, highlighting the influence of pulse characteristics and nuclear Zeeman effects.

Findings

Nuclear frequency focusing depends on pulse parameters and magnetic field strength.

The classical model effectively describes the non-equilibrium nuclear spin states.

External magnetic fields significantly influence the nuclear spin dynamics.

Abstract

The coherence of an electronic spin in a semiconductor quantum dot decays due to its interaction with the bath of nuclear spins in the surrounding isotopes. This effect can be reduced by subjecting the system to an external magnetic field and by applying optical pulses. By repeated pulses in long trains the spin precession can be synchronized to the pulse period $T_\text{R}$. This drives the nuclear spin bath into states far from equilibrium leading to nuclear frequency focusing. In this paper, we use an efficient classical approach introduced in Phys. Rev. B $\textbf{96}$, 054415 (2017) to describe and to analyze this nuclear focusing. Its dependence on the effective bath size and on the external magnetic field is elucidated in a comprehensive study. We find that the characteristics of the pulse as well as the nuclear Zeeman effect influence the behavior decisively.