Strong coupling and induced transparency at room temperature with single quantum dots and gap plasmons

Area of Science:

• Optics and photonics
• Materials science
• Quantum mechanics

Background:

• Coherent coupling between plasmons and emitters leads to spectral effects like vacuum Rabi splitting and Fano interference.
• Achieving strong or intermediate coupling is key for single-photon nonlinearities and extreme light-matter interactions at the nanoscale.
• Distinguishing these effects solely through scattering measurements can be challenging due to similar spectral features.

Purpose of the Study:

• To unambiguously demonstrate weak coupling (Purcell effect), intermediate coupling (Fano interference), and strong coupling (Rabi splitting) in individual plasmon-emitter systems.
• To explore the potential for nanoscale nonlinear optics and extreme light-matter interactions at room temperature.

Main Methods:

• Fabrication of coupled plasmon-emitter systems using a single colloidal quantum dot between a gold nanoparticle and a silver film.
• Simultaneous measurements of scattering and photoluminescence from individual systems.
• Room-temperature characterization of coupling regimes.

Main Results:

• Unambiguous demonstration of weak coupling (Purcell effect), intermediate coupling (Fano interference), and strong coupling (Rabi splitting).
• Distinct spectral signatures of each coupling regime were observed and differentiated using both scattering and photoluminescence.
• Successful room-temperature observation of these quantum phenomena.

Conclusions:

• Coherent coupling between plasmons and quantum dots enables tunable light-matter interactions.
• The developed system provides a platform for studying fundamental quantum optics and developing nanoscale optical devices.
• This research highlights the potential for extreme light-matter interactions at room temperature, relevant for quantum information processing and sensing.