Quantized Vortices and Four-Component Superfluidity of Semiconductor Excitons

Area of Science:

• Condensed matter physics
• Quantum optics
• Semiconductor physics

Background:

• Spatially indirect excitons in quantum wells are crucial for exploring exotic quantum phenomena.
• Understanding exciton-exciton interactions is key to Bose-Einstein condensation and superfluidity.
• Previous studies have explored exciton condensates, but achieving robust superfluidity with distinct components remains challenging.

Purpose of the Study:

• To investigate the formation and properties of a superfluid state in spatially indirect excitons within a GaAs quantum well system.
• To identify quantum signatures indicative of superfluidity, such as macroscopic spatial coherence and quantized vortices.
• To explore the role of optically bright and dark excitons in the formation of a multi-component superfluid.

Main Methods:

• Confining spatially indirect excitons from GaAs quantum wells in a 10 μm electrostatic trap.
• Utilizing weak photoluminescence spectroscopy to detect quantum signatures below a critical temperature of approximately 1 K.
• Analyzing the exciton density regime to identify conditions favorable for superfluid formation.

Main Results:

• Macroscopic spatial coherence and quantized vortices were detected in the photoluminescence below 1 K.
• These quantum signatures were observed in a dilute regime, within a narrow range of exciton density.
• Evidence suggests the formation of a four-component superfluid comprising optically bright and dark excitons.

Conclusions:

• The study demonstrates the formation of a novel four-component superfluid from spatially indirect excitons in GaAs quantum wells.
• The observed quantum phenomena, including coherence and vortices, highlight the potential for Bose-Einstein condensation in dilute exciton systems.
• The findings open new avenues for exploring multi-component superfluidity and quantum correlations in semiconductor systems.