Interference between multipolar two-photon transitions in quantum emitters near plasmonic nanostructures

Area of Science:

• Quantum optics
• Plasmonics
• Nanophotonics

Background:

• Spontaneous emission near plasmonic nanostructures involves complex multipolar pathways beyond simple dipole emission.
• Two-photon spontaneous emission (TPSE) exhibits higher-order multipolar emission channels that can interfere.
• Understanding these interference effects is crucial for controlling light-matter interactions at the nanoscale.

Purpose of the Study:

• To develop a novel computational framework for analyzing interference effects in TPSE near arbitrary nanostructures.
• To investigate the breakdown of dipolar selection rules in TPSE due to enhanced multipolar transitions.
• To provide a tool for designing quantum emitters and nanostructures for tailored TPSE.

Main Methods:

• Developed a framework based on calculating Purcell factors using conventional electromagnetic simulations.
• Avoided complex analytical calculations by leveraging established simulation techniques.
• Applied the framework to a hydrogen-like emitter near a graphene nanotriangle.

Main Results:

• Demonstrated a breakdown of the dipolar selection rule in TPSE near a graphene nanotriangle.
• Observed significant enhancement of two-electric dipole (2ED) and two-electric quadrupole (2EQ) transitions.
• Quantified the impact of interference between multipolar transitions, showing an increase in the total emission rate.

Conclusions:

• The developed framework accurately computes interference effects in TPSE near nanostructures.
• Multipolar transitions and their interference play a significant role in TPSE, challenging dipolar selection rules.
• Exploiting these interference effects offers a new degree of freedom for enhancing or suppressing specific TPSE pathways.