Persistent Self-Induced Larmor Precession Evidenced through Periodic Revivals of Coherence

Area of Science:

• Quantum optics
• Condensed matter physics
• Semiconductor physics

Background:

• Exciton-polariton condensates are Bose-Einstein condensates formed from exciton-photon quasiparticles in semiconductor microcavities.
• Their quantum properties, including spin dynamics, are of great interest for fundamental research and potential applications.

Purpose of the Study:

• To investigate the spin dynamics of an optically trapped exciton-polariton condensate under a single optical pulse.
• To understand the origin and control mechanisms of persistent pseudo-spin precession.

Main Methods:

• Interferometric measurements were performed on an optically trapped exciton-polariton condensate.
• The system was subjected to a single, pulsed optical excitation.
• Analysis focused on the pseudo-spin precession dynamics and its dependence on condensate properties.

Main Results:

• A regime of persistent pseudo-spin precession was observed, with over 10^5 precessions in a single 20 μs pulse.
• The precession frequency exhibited remarkable stability.
• Nonlinear polariton interactions were identified as the source of a self-induced out-of-plane magnetic field driving the spin dynamics.
• Larmor precession frequency and trajectory were found to be controllable via condensate density using optical means.

Conclusions:

• The study demonstrates optically controllable persistent spin precession in exciton-polariton condensates.
• These findings highlight the potential for developing advanced magnetometry devices based on this system.
• The research opens avenues for creating spin-squeezed polariton condensates.