Single Photon Source from a Nanoantenna-Trapped Single Quantum Dot

TL;DR

This paper demonstrates a nanoantenna-based method to trap and enhance single quantum dot emission, producing bright, stable single photon sources suitable for quantum technologies.

Contribution

It introduces a nanoantenna design that automatically traps quantum dots and enhances their emission without additional processing.

Findings

7x increased brightness of quantum dots

50x reduction in blinking behavior

Antibunching below 0.5 confirming single photon emission

Abstract

Single photon sources with high brightness and subnanosecond lifetimes are key components for quantum technologies. Optical nanoantennas can enhance the emission properties of single quantum emitters, but this approach requires accurate nanoscale positioning of the source at the plasmonic hotspot. Here, we use plasmonic nanoantennas to simultaneously trap single colloidal quantum dots and enhance their photoluminescence. The nano-optical trapping automatically locates the quantum emitter at the nanoantenna hotspot without further processing. Our dedicated nanoantenna design achieves a high trap stiffness of 0.6 fN/nm/mW for quantum dot trapping, together with a relatively low trapping power of 2 mW/$\mu$m$^2$. The emission from the nanoantenna-trapped single quantum dot shows 7x increased brightness, 50x reduced blinking, 2x shortened lifetime and a clear antibunching below 0.5 demonstrating true single photon emission. Combining nano-optical tweezers with plasmonic enhancement is a promising route for quantum technologies and spectroscopy of single nano-objects.