Enhancement of Spin Coherence using Q-factor Engineering in Semiconductor Microdisk Lasers

TL;DR

This paper demonstrates that engineering the Q-factor of semiconductor microdisk lasers can significantly enhance electron spin coherence times, with potential implications for quantum information processing.

Contribution

It introduces a method to enhance spin lifetime in microdisk lasers by Q-factor engineering, contrasting with traditional Purcell effect expectations.

Findings

Spin lifetime is increased when excitation resonates with high-Q lasing modes.

Cavity design modifications can manipulate spin coherence enhancement.

Resonant enhancement is achieved despite the typical Purcell effect expectations.

Abstract

Semiconductor microcavities offer unique means of controlling light-matter interactions, which have led to the development of a wide range of applications in optical communications and inspired proposals for quantum information processing and computational schemes. Studies of spin dynamics in microcavities - a new and promising research field - have revealed novel effects such as polarization beats, stimulated spin scattering, and giant Faraday rotation. Here, we study the electron spin dynamics in optically-pumped GaAs microdisk lasers with quantum wells (QWs) and interface-fluctuation quantum dots (QDs) in the active region. In particular, we address the question of how the electron spin dynamics are modified by the stimulated emission in the disks, and observe an enhancement of the spin lifetime when the optical excitation is in resonance with a high quality (Q ~ 5000) lasing mode. This resonant enhancement, contrary to what is expected from the Purcell effect observed in the cavities, is then manipulated by altering the cavity design and dimensions.