Mode-multiplexing deep-strong light-matter coupling

Area of Science:

• Quantum optics
• Metasurface engineering
• Condensed matter physics

Background:

• Cavity quantum electrodynamics typically maximizes light-matter coupling via resonance.
• Single electronic excitations have finite oscillator strength, limiting coupling strength.
• Virtual photons dress electronic states, inducing phenomena like polaritonic chemistry.

Purpose of the Study:

• To explore a new regime of ultrastrong light-matter interaction beyond conventional limits.
• To engineer metasurfaces for enhanced coupling using non-resonant magnetoplasmon modes.
• To investigate the resulting exotic quantum effects and ultrabroadband polaritons.

Main Methods:

• Utilizing tailored metasurfaces to excite cooperative dipole moments of multiple magnetoplasmon modes.
• Employing non-resonant interactions to overcome limitations of single electronic excitations.
• Calculating vacuum ground state populations and coupling strengths.

Main Results:

• Achieved record-strong light-matter coupling strengths.
• Generated an ultrabroadband spectrum of 20 polaritons spanning 6 optical octaves.
• Observed vacuum ground state populations exceeding 1 virtual excitation quantum.
• Demonstrated subcycle energy exchange between bosonic vacuum modes and entanglement of electronic excitations via vacuum fluctuations.

Conclusions:

• Metasurface-engineered non-resonant magnetoplasmons enable a new regime of ultrastrong light-matter interaction.
• This approach overcomes fundamental limitations of traditional cavity quantum electrodynamics.
• The observed phenomena open avenues for novel quantum technologies and fundamental physics exploration.