Observation of a Long-Range Interaction between Semiconductor Quantum Dots

TL;DR

This paper reports the observation of long-range electromagnetic interactions between distant semiconductor quantum dots, revealing a resonant lifetime enhancement due to mutual coupling extending beyond nearest neighbors.

Contribution

It demonstrates for the first time that quantum dots can interact electromagnetically over long distances, showing a subradiance-like effect in their exciton lifetimes.

Findings

Resonant enhancement of exciton lifetime at the QD ground state transition

Electromagnetic coupling extends beyond nearest neighbors

Observation of subradiance-like behavior in quantum dot ensembles

Abstract

We demonstrate electromagnetic interaction between distant quantum dots (QDs), as is observed from transient pump-probe differential reflectivity measurements. The QD-exciton lifetime is measured as a function of the probe photon energy and shows a strong resonant behavior with respect to the QD density of states. The observed exciton lifetime spectrum reveals a subradiance-like coupling between the QD, with a 12 times enhancement of the lifetime at the center of the ground state transition. This effect is due to a mutual electromagnetic coupling between resonant QDs, which extends over distances considerably beyond the nearest neighbor QD-QD separation.