Quantum dot emits indistinguishable single photons

Sept. 11, 2015
Transform-limited source is useful in quantum information technology.

Physicists at the University of Basel (Basel, Switzerland) and the University of Bochum (Bochum, Germany) have developed a semiconductor quantum-dot light source that emits single, identical photons.1

Single-photon sources are important in the field of quantum information technology where, for example, they are used in quantum computers. Alongside the brightness and robustness of the light source, the indistinguishability of the photons is especially crucial. In particular, this means that all photons must be precisely the same wavelength ("transform limited"). Creating such a source of identical single photons has proven very difficult in the past.

However, quantum dots made of semiconductor materials are offering new hope. Single electrons can be trapped inside a quantum dot and are confined on a nanometer scale. An individual photon is emitted when a quantum state decays.

Noise in the semiconductor helps indistinguishability

A team of scientists led by Andreas Kuhlmann and Richard Warburton from the University of Basel has already shown in past publications that the indistinguishability of the photons is reduced by the fluctuating nuclear spins of the quantum-dot atoms. Now, the scientists have controlled the nuclear spins to such an extent that even photons sent out widely separated in time (a timescale on the order of a second) are the same wavelength.

Quantum cryptography and quantum communication are two potential areas of application for single-photon sources.

Source: https://www.unibas.ch/en/News-Events/News/Uni-Research/Researchers-in-Basel-Develop-Ideal-Single-Photon-Source.html

REFERENCE:

1. Andreas V. Kuhlmann et al., Nature Communications (2015); doi: 10.1038/ncomms9204

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.

Sponsored Recommendations

Advancing Neuroscience Using High-Precision 3D Printing

March 7, 2025
Learn how Cold Spring Harbor Laboratory Used High-Precision 3D Printing to Advance Neuroscience Research using 3D Printed Optical Drives.

From Prototyping to Production: How High-Precision 3D Printing is Reinventing Electronics Manufacturing

March 7, 2025
Learn how micro 3D printing is enabling miniaturization. As products get smaller the challenge to manufacture small parts increases.

Sputtered Thin-film Coatings

Feb. 27, 2025
Optical thin-film coatings can be deposited by a variety of methods. Learn about 2 traditional methods and a deposition process called sputtering.

What are Notch Filters?

Feb. 27, 2025
Notch filters are ideal for applications that require nearly complete rejection of a laser line while passing as much non-laser light as possible.

Voice your opinion!

To join the conversation, and become an exclusive member of Laser Focus World, create an account today!