Lasers & Sources

A single quantum dot in a microcavity produces indistinguishable photons for quantum devices

March 8, 2016

With this brighter single-photon source, quantum optical computers may now be slightly less far off.

This image shows three single-photon sources. In each, a quantum dot is placed in the center of the cavity, which consists of a 3 µm pillar connected to a circular frame by guides that are 1.3 µm wide. By applying electrical voltage to the cavity, the wavelength of the emitted photons can be tuned and the charge noise totally eliminated.

A new ultrabright source of single photons that is 20 times brighter than commonly used sources, and which emits photons that are 99.5% indistinguishable from one another, has been developed by researchers from the CNRS-LPN Laboratoire de Photonique et de Nanostructures, Université Paris-Saclay (Marcoussis, France), the University of Queensland (Brisbane, Australia), Université Grenoble Alpes (Grenoble, France), CNRS, Institut Néel (Grenoble, France), Université Paris Diderot (Paris, France), and Ecole Polytechnique, Université Paris-Saclay (Palaiseau, France).¹

This feat was achieved thanks to the nanometrically precise positioning of a single quantum dot within an optical microcavity. Adding an electrical bias to the device helped reduce the "noise" around the quantum dot, which generally renders photons different from one another.

The results make it possible to conduct quantum computing of unprecedented complexity, a first step toward the creation of optical quantum computers.

Source: http://www.alphagalileo.org/ViewItem.aspx?ItemId=161714&CultureCode=en

REFERENCE:

1. Niccolo Somaschi et al., Nature Photonics (2016); doi:10.1038/Nphoton.2016.23

About the Author

John Wallace | Senior Technical Editor (1998-2022)

John Wallace was with Laser Focus World for nearly 25 years, retiring in late June 2022. He obtained a bachelor's degree in mechanical engineering and physics at Rutgers University and a master's in optical engineering at the University of Rochester. Before becoming an editor, John worked as an engineer at RCA, Exxon, Eastman Kodak, and GCA Corporation.