Cavity-driven attractive interactions in quantum materials

Area of Science:

• Quantum Materials Science
• Optoelectronics
• Condensed Matter Physics

Background:

• Many-body phenomena in quantum materials arise from complex electronic interactions.
• Controlling these interactions is key to discovering new quantum phases.
• Optical cavities offer a promising method to tailor electronic properties using light.

Purpose of the Study:

• To demonstrate terahertz cavity photons mediating attractive interactions in van der Waals materials.
• To investigate the reorganization of electron-hole transitions into exciton-like states.
• To establish a platform for studying hybrid light-matter phases in 2D quantum matter.

Main Methods:

• Integration of exfoliated, dual-gated 2D quantum materials into a terahertz cavity.
• Development of a broadband, sub-wavelength time-domain microscope for spectroscopic measurements.
• Spectroscopic measurement of the field-tunable bandgap of bilayer graphene (BLG) in the terahertz range.

Main Results:

• Observation of ultrastrong coupling (USC) between BLG and terahertz cavity photons.
• Effective interaction strength exceeding 40% of the bare photon energy at resonance.
• Identification of a stable, cavity-induced resonance resembling excitons, emerging from the interband continuum.

Conclusions:

• Terahertz cavity photons can effectively mediate interactions and form exciton-like states in 2D quantum materials.
• The developed platform enables precise control and investigation of light-matter interactions in quantum systems.
• This work paves the way for designing and exploring novel hybrid light-matter phases in quantum materials.