Theory on the Ultrafast Manipulation of Electron Spin by Optical Means

TL;DR

This paper presents a comprehensive theoretical analysis of ultrafast optical control of electron spins in quantum wells, improving existing models and exploring effects of hole spin relaxation, with implications for quantum dot applications.

Contribution

It introduces an improved theoretical model for optical manipulation of electron spins and analyzes the impact of hole spin relaxation on coherence in doped and undoped quantum wells.

Findings

Enhanced expression for optical-pulse-induced effective magnetic field.

Coherent control is robust in doped quantum wells despite hole-spin relaxation.

Theoretical results corroborate previous experimental findings.

Abstract

Based on a multi-particle-state stimulated Raman adiabatic passage approach, a comprehensive theoretical study on the ultrafast optical manipulation of electron spins in quantum wells is presented. In addition to corroborating the experimental findings [Science {\bf 292}, 2458 (2001)], we improve the expression of the optical-pulse-induced effective magnetic field, in comparison with the one obtained via the conventional single-particle ac-Stark shift. Further study of the effect of hole spin relaxation reveals that while the coherent optical manipulation of electron spin in undoped quantum wells would deteriorate in the presence of relatively fast hole-spin relaxation, the coherent control in doped systems can be quite robust against the decoherence. The implications of present results on quantum dots will also be discussed.