Enhancement of spin coherence using Q-factor engineering in semiconductor microdisc lasers.

Area of Science:

• Optoelectronics
• Quantum Information Science
• Materials Science

Background:

• Semiconductor microcavities enable control over light-matter interactions for applications in optical communications and quantum technologies.
• Electron spin dynamics in microcavities is an emerging research area with observed phenomena like polarization beats and giant Faraday rotation.

Purpose of the Study:

• To investigate electron spin dynamics in optically pumped GaAs microdisc lasers.
• To understand how stimulated emission influences electron spin dynamics.
• To explore the enhancement of spin-coherence time through resonant optical excitation.

Main Methods:

• Utilized optically pumped GaAs microdisc lasers with quantum wells and quantum dots.
• Examined electron spin dynamics under varying optical excitation conditions.
• Investigated the effect of cavity design and dimensions on spin dynamics.

Main Results:

• Observed an enhancement of electron spin-coherence time when optical excitation was resonant with a high-quality (Q ≈ 5,000) lasing mode.
• Demonstrated that this resonant enhancement is contrary to the trend in carrier-recombination time.
• Showed that the spin-coherence enhancement can be manipulated by altering cavity design and dimensions.

Conclusions:

• Coherent interactions between electron spins and photons can be engineered in semiconductor microcavities.
• This engineered coherence may lead to novel spin-dependent quantum optoelectronic devices.
• The findings offer new pathways for developing advanced quantum information processing and computational schemes.