Increasing the collection efficiency of single photon sources for quantum technology

Efficient single photon sources have applications in various quantum technologies, such as quantum key distribution and quantum metrology. Quantum dot emitters provide on-demand production of single photons, but the photons are emitted in all directions, which results in low collection efficiency.

Abudayyeh et al. increased the directionality of photons emitted from quantum dots operating at room temperature by placing them in nanoantennas. They achieved a record-high collection efficiency of 85% of the emitted single photons.

The nanoantennas directed the photons in a single direction, increasing the number of collected photons. The authors optimized the coupling between the antennas and quantum dots with improved antenna fabrication techniques and enhanced quantum dots known as CdSe/CdS core/thick-shell or giant quantum dots, which are non-blinking and non-photobleaching at room temperature.

“We have come up with a novel fabrication and placement method that enables us to reach record-high collection efficiencies even with such broadband emitters,” said author Hamza Abudayyeh.

The authors hope the nanoantenna fabrication method they developed will aid in the eventual application of the antennas. Unlike previously used indeterministic or single-try methods, their placement method, dip-pen nanolithography, allowed them to directly and precisely write the quantum dots in the nanoantennas. This method is more suitable for scaling. The quantum dots also demonstrated high photon rates of many emitted photons.

The authors plan couple these on-chip, room temperature nanoantenna-emitter devices with a fiber to produce plug-and-play single photon sources with high collection efficiencies.

Source: “Single photon sources with near unity collection efficiencies by deterministic placement of quantum dots in nanoantennas,” by Hamza Abudayyeh, Boaz Lubotzky, Anastasia Blake, Jun Wang, Somak Majumder, Zhongjian Hu, Younghee Kim, Han Htoon, Riya Bose, Anton V. Malko, Jennifer A. Hollingsworth, and Ronen Rapaport, APL Photonics (2021). The article can be accessed at https://aip.scitation.org/doi/full/10.1063/5.0034863 .