Single-molecule strong coupling at room temperature in plasmonic nanocavities

Area of Science:

• Quantum Optics
• Nanotechnology
• Physical Chemistry

Background:

• Optical cavities modify light-emitter interactions, enhancing light extraction in the weak-coupling regime.
• Strong coupling between single emitters and optical cavities creates light-matter hybrid states, crucial for quantum information systems.
• Previous strong-coupling studies required low temperatures and complex fabrication, limiting practical applications.

Purpose of the Study:

• To achieve strong coupling at room temperature and ambient conditions.
• To explore the use of host-guest chemistry for precise molecule alignment within nanocavities.
• To demonstrate the potential for manipulating molecular properties and photochemistry through light-matter interaction.

Main Methods:

• Fabrication of plasmonic nanocavities with volumes under 40 cubic nanometres.
• Utilizing host-guest chemistry to align 1-10 methylene-blue molecules within the cavities.
• Characterization using dispersion curves, vibrational spectroscopy, and dark-field scattering spectra.

Main Results:

• Demonstrated strong coupling regime at room temperature and ambient conditions.
• Observed characteristic light-matter mixing with Rabi frequencies of 300 meV (10 molecules) down to 90 meV (1 molecule).
• Provided evidence of single-molecule strong coupling through statistical analysis of spectroscopic data.

Conclusions:

• Achieved practical strong coupling in cavity quantum electrodynamics using scalable nanotechnology.
• The light-matter dressing of molecules opens avenues for modifying photochemistry and exploring natural processes like photosynthesis.
• Potential applications include ultralow-power switches, lasers, and the manipulation of chemical bonds.