Giant hyperfine interaction between a dark exciton condensate and nuclei

Area of Science:

• Condensed matter physics
• Quantum optics
• Solid-state physics

Background:

• Dark exciton Bose-Einstein condensates (BECs) are exotic quantum states with potential applications.
• Understanding their interactions with nuclear spins is crucial for controlling quantum phenomena.

Purpose of the Study:

• To investigate the interaction between dark exciton BECs and nuclei in semiconductor quantum wells.
• To elucidate the mechanism behind nuclear spin polarization observed in these systems.

Main Methods:

• Fabrication of gallium arsenide/aluminum gallium arsenide coupled quantum wells.
• Optical excitation and photoluminescence spectroscopy.
• Application of radio frequency radiation to probe hyperfine interactions.

Main Results:

• Observed nuclear polarization buildup correlated with dark exciton BEC formation.
• Demonstrated polarization extending beyond the excitation area and persisting for seconds.
• Measured a two-orders-of-magnitude enhancement in hyperfine interaction under radio frequency radiation.

Conclusions:

• The study provides clear evidence for nuclear polarization driven by dark exciton BECs.
• The collective nature of the N-exciton condensate amplifies the nuclear-electron spin interaction.
• Findings suggest novel pathways for manipulating nuclear spins in quantum systems.