Tuning Near-Field Interactions Using the Bright and Dark States of a Quantum Dot

TL;DR

This paper shows how the internal states of quantum dots can be used to control near-field interactions, revealing that quantum yield influences energy transfer and field enhancement, which explains blinking suppression near metal surfaces.

Contribution

It introduces a method to tune near-field interactions via quantum dot internal states, linking quantum yield to energy transfer and field enhancement effects.

Findings

Energy transfer is suppressed at low quantum yield states.

Blinking suppression near metal surfaces is due to fast energy transfer.

Quantum dot internal states can be used to control near-field coupling.

Abstract

We demonstrate that the cycling between internal states of quantum dots during fluorescence blinking can be used to tune the near-field coupling with a sharp tip. In particular, the balance between tip-induced field enhancement and energy transfer depends explicitly on the intrinsic quantum yield of the quantum dot. Our measurements show that for internal states with low quantum yield, energy transfer is strongly suppressed in favor of field enhancement, and explicitly demonstrate that suppressed blinking of quantum dots near metal surfaces is due to fast energy transfer.