Quantum electrodynamics at room temperature coupling a single vibrating molecule with a plasmonic nanocavity.

Ojambati, Oluwafemi S; Chikkaraddy, Rohit; Deacon, William D; Horton, Matthew; Kos, Dean; Turek, Vladimir A; Keyser, Ulrich F; Baumberg, Jeremy J · Nat Commun · 2019

basic_science · Level V

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Abstract

Interactions between a single emitter and cavity provide the archetypical system for fundamental quantum electrodynamics. Here we show that a single molecule of Atto647 aligned using DNA origami interacts coherently with a sub-wavelength plasmonic nanocavity, approaching the cooperative regime even at room temperature. Power-dependent pulsed excitation reveals Rabi oscillations, arising from the coupling of the oscillating electric field between the ground and excited states. The observed single-molecule fluorescent emission is split into two modes resulting from anti-crossing with the plasmonic mode, indicating the molecule is strongly coupled to the cavity. The second-order correlation function of the photon emission statistics is found to be pump wavelength dependent, varying from g<sup>(2)</sup>(0) = 0.4 to 1.45, highlighting the influence of vibrational relaxation on the Jaynes-Cummings ladder. Our results show that cavity quantum electrodynamic effects can be observed in molecular systems at ambient conditions, opening significant potential for device applications.