Coherent spin dynamics of electrons and holes in semiconductor quantum wells and quantum dots under periodical optical excitation: resonant spin amplification versus spin mode-locking

TL;DR

This paper investigates the coherent spin dynamics of electrons and holes in semiconductor quantum wells and dots under periodic optical excitation, revealing how resonant spin amplification and spin mode-locking arise from the same fundamental processes.

Contribution

It provides a theoretical analysis of spin polarization generation and dephasing, explaining the conditions under which resonant spin amplification and mode-locking occur in semiconductor nanostructures.

Findings

Resonant spin amplification and mode-locking share the same origin.

Both regimes depend on pump power and spin precession frequency spread.

The study offers insights into controlling spin coherence in quantum structures.

Abstract

The coherent spin dynamics of resident carriers, electrons and holes, in semiconductor quantum structures is studied by periodical optical excitation using short laser pulses and in an external magnetic field. The generation and dephasing of spin polarization in an ensemble of carrier spins, for which the relaxation time of individual spins exceeds the repetition period of the laser pulses, are analyzed theoretically. Spin polarization accumulation is manifested either as resonant spin amplification or as mode-locking of carrier spin coherences. It is shown that both regimes have the same origin, while their appearance is determined by the optical pump power and the spread of spin precession frequencies in the ensemble.