Researchers develop ideal single-photon source

September 7, 2015, University of Basel
Semiconductor quantum dot emitting a stream of identical photons.

With the help of a semiconductor quantum dot, physicists at the University of Basel have developed a new type of light source that emits single photons. For the first time, the researchers have managed to create a stream of identical photons. They have reported their findings in the scientific journal Nature Communications together with colleagues from the University of Bochum.

A single-photon source never emits two or more photons at the same time. Single photons 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 the same color. 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. A quantum dot is a collection of a few hundred thousand atoms that can form itself into a semiconductor under certain conditions. Single electrons can be captured in these quantum dots and locked into a very small area. An individual photon is emitted when an engineered quantum state collapses.

Noise in the semiconductor

A team of scientists led by Dr. Andreas Kuhlmann and Prof. Richard J. Warburton from the University of Basel have already shown in past publications that the indistinguishability of the photons is reduced by the fluctuating nuclear spin of the quantum dot atoms. For the first time ever, the scientists have managed to control the nuclear spin to such an extent that even photons sent out at very large intervals are the same color.

Quantum cryptography and quantum communication are two potential areas of application for single-photon sources. These technologies could make it possible to perform calculations that are far beyond the capabilities of today's computers.

Explore further: Highly stable quantum light source for applications in quantum information developped

More information: "Transform-limited single photons from a single quantum dot," Nature Communications 6:8204 (2015) | DOI: 10.1038/ncomms9204

Related Stories

Quantum networks: Back and forth are not equal distances

July 27, 2015

Quantum technology based on light (photons) has great potential for radically new information technology based on photonic circuits. Up to now, the photons in quantum photonic circuits have behaved in the same way whether ...

A little light interaction leaves quantum physicists beaming

August 24, 2015

A team of physicists at the University of Toronto (U of T) have taken a step toward making the essential building block of quantum computers out of pure light. Their advance, described in a paper published this week in Nature ...

Recommended for you

Muons spin tales of undiscovered particles

April 20, 2018

Scientists at U.S. Department of Energy (DOE) national laboratories are collaborating to test a magnetic property of the muon. Their experiment could point to the existence of physics beyond our current understanding, including ...

Integrating optical components into existing chip designs

April 19, 2018

Two and a half years ago, a team of researchers led by groups at MIT, the University of California at Berkeley, and Boston University announced a milestone: the fabrication of a working microprocessor, built using only existing ...

3 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

dbsi
5 / 5 (1) Sep 07, 2015
Quantum cryptography and quantum communication are two potential areas of application for single-photon sources. These technologies could make it possible to perform calculations that are far beyond the capabilities of today's computers.

Did you wanted to list quantum computing too? The last sentence would make more sense.
docile
Sep 07, 2015
This comment has been removed by a moderator.
swordsman
not rated yet Sep 08, 2015
Significant accomplishment. Next step is to characterize the system through measurements and modeling. Heisenberg has nothing to do with this, as all physical phenomena exhibit the uncertainty of measurement. Nevertheless, this uncertainty can always be determined.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.