Quantum Emitter Integration May Enable Quantum Circuits

Researchers integrated silicon photonic devices with a solid-state single photon emitter, using a hybrid approach that combines silicon photonic waveguides with quantum dots. The silicon photonic waveguides were used for manipulating light, and the InAs/InP quantum dots were used to generate light efficiently at wavelengths spanning the O-band and C-band.

A schematic of the integrated InP nanobeam and silicon waveguide. Courtesy of UNIST.

The research team, from Ulsan National Institute of Science and Technology (UNIST) and the University of Maryland, removed the quantum dots via a pick-and-place procedure, using a microprobe tip combined with a focused ion beam and scanning electron microscope. Using the pick-and-place technique the researchers positioned epitaxially grown InAs/InP quantum dots, emitting at telecom wavelengths, on a silicon photonic chip with nanoscale precision. They used an adiabatic tapering approach to efficiently transfer the emission from the quantum dots to the waveguide. The researchers also incorporated an on-chip silicon-photonic beamsplitter to perform a Hanbury-Brown and Twiss measurement.

This is a scanning electron microscope image of the fabricated nanobeam that is suspended by thin tethers that attach it to the bulk substrate. Courtesy of UNIST.

The research team believes their approach could enable integration of precharacterized III–V quantum photonic devices into large-scale photonic structures, which would enable complex devices composed of many emitters and photons.

“In order to build photon-based integrated quantum optical devices, it is necessary to produce as many quantum light sources as possible in a single chip,” said UNIST professor Je-Hyung Kim. “Through this study, we have proposed the basic form of quantum optical devices by producing a highly effective quantum light source with quantum dots and creating the pathway to manipulate light with the use of silicon substrates.”

The research team said the integration “opens up the possibility to leverage the highly advanced photonics capabilities developed in silicon to control and route nonclassical light from on-demand single photon sources. In addition, the fabricated devices operate at telecom wavelengths and can be electrically driven, which is useful for fiber-based quantum communication.”

The research was published in Nano Letters (doi: 10.1021/acs.nanolett.7b03220).