Single Photon Sources with Near Unity Collection Efficiencies by Deterministic Placement of Quantum Dots in Nanoantennas

TL;DR

This paper demonstrates a method for precisely positioning quantum dots in nanoantennas to achieve near-unity collection efficiency of single photons, advancing scalable quantum network technologies.

Contribution

It introduces a deterministic placement technique for quantum emitters in nanoantennas, enabling highly efficient photon collection suitable for quantum communication.

Findings

Achieved 85% collection efficiency of single photons into a low NA channel.

Developed a method for high-precision placement of quantum dots in nanoantennas.

Enabled efficient coupling of quantum emitters to fiber or free-space channels.

Abstract

Deterministic coupling between photonic nodes in a quantum network is an essential step towards implementing various quantum technologies. The omnidirectionality of free-standing emitters, however, makes this coupling highly inefficient, in particular if the distant nodes are coupled via low numerical aperture (NA) channels such as optical fibers. This limitation requires placing quantum emitters in nanoantennas that can direct the photons into the channels with very high efficiency. Moreover, to be able to scale such technologies to a large number of channels, the placing of the emitters should be deterministic. In this work we present a method for directly locating single free-standing quantum emitters with high spatial accuracy at the center of highly directional bullseye metal-dielectric nanoantennas. We further employ non-blinking, high quantum yield colloidal quantum dots (QDs) for on-demand single-photon emission that is uncompromised by instabilities or non-radiative exciton recombination processes. Taken together this approach results in a record-high collection efficiency of 85% of the single photons into a low NA of 0.5, setting the stage for efficient coupling between on-chip, room temperature nanoantenna-emitter devices and a fiber or a remote free-space node without the need for additional optics.