Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Strong interactions between photons mediated by a single atom

28.06.2018

Physicists at MPQ in Garching observe strong interactions between photons of different colour in an atom-cavity system.

Who would not want to have a light saber? While the idea from science fiction has sparked our imagination, technical realization of this fantasy is elusive, since photons, the particles that make up light, do not interact.


Doctoral candidate Nicolas Tolazzi holding a toy light saber in front of the experiment.

Photo: MPQ, Quantum Dynamics Division

Already from everyday experience, we know that two light beams, whether radiation of traditional lamps or laser beams, pass each other undisturbed. However, this same quality makes photons useful as stable carriers of quantum information for quantum communication and computing.

On the other hand, processing of the quantum information again requires controlled interactions between photons at so-called quantum nodes that carry out computations.

Physicists from the Quantum Dynamics Division at the Max Planck Institute of Quantum Optics have now demonstrated such a controlled interaction between light beams of different colour at the level of single photons. Making use of a single atom in an optical cavity, they observed two regimes in which the fields either block each other or only transit the system conjunctively. As a first immediate application, they show an optical switch where one beam turns off the other.

Though particles, photons exhibit neither mass nor charge. As a consequence they do not interact with each other. Their electric field, however, causes them to interact with charged particles in matter. In case this interaction is nonlinear and sufficiently strong, it may in turn be used to mediate interactions between photons. The probably most dramatic effect is observed for a single atom with only two levels, excited and ground state: absorption of a first photon would turn the absorber into an emitter and, therefore, a second photon is transmitted depending on the presence of that prior photon.

A major challenge over the past 30 years has been to make the corresponding interaction probability, negligible for a single atom in free space, large. Placing the atom between two high-quality mirrors that cause the photon to pass the atom repeatedly and confine it to a small volume at its location, was demonstrated to yield strong single-photon interaction. However, its effect is mostly observed on the photon statistics, as long as it only mediates interactions between indistinguishable photons of a single beam. Examples are single- and two-photon blockade.

Bringing a second light field into the cavity formed by the mirrors and finding a suitable energy level structure, it is possible to implement interactions between distinguishable photons of different colour. While technically challenging, Christoph Hamsen and co-workers realized a so-called N-type system and observe novel effects of mutual blocking and conjunct transit where photons of the different fields either block each other or only transit the system together. Employing the regime of blockade, they demonstrate an optical switch where each field may toggle the other one ON or OFF.

These effects stem from the novel energy level structure for the joint system that is formed by the strong coupling between the two light fields and the atom. In this level scheme, each selectively-addressable state reflects a specific number of photons in each of the two fields which correlates their number in both beams.

While light sabers remain elusive, the new system displays coherent interaction and forms a new doubly nonlinear level scheme that opens the route towards quantum nonlinear sensing where the number of photons in one beam may measure the number of photons in the other.

Original publication:

Christoph Hamsen, Karl Nicolas Tolazzi, Tatjana Wilk, and Gerhard Rempe
Strong coupling between photons of two light fields mediated by one atom
Nature Physics, http://dx.doi.org/10.1038/s41567-018-0181-1

Contact:

Dr. Tatjana Wilk
Max Planck Institute of Quantum Optics
Hans-Kopfermann-Straße 1
85748 Garching
Phone: +49 (0)89 / 3290 5670
E-mail: tatjana.wilk@mpq.mpg.de

Nicolas Tolazzi
Max Planck Institute of Quantum Optics
Phone: +49 (0)89 / 3290 5296
E-mail: nicolas.tolazzi@mpq.mpg.de

Prof. Dr. Gerhard Rempe
Director at the Max Planck Institute of Quantum Optics
Phone: +49 (0)89 / 3290 5701
E-mail: gerhard.rempe@mpq.mpg.de

Dr. Olivia Meyer-Streng | Max-Planck-Institut für Quantenoptik
Further information:
http://www.mpq.mpg.de/

More articles from Physics and Astronomy:

nachricht UNH scientists help provide first-ever views of elusive energy explosion
16.11.2018 | University of New Hampshire

nachricht NASA keeps watch over space explosions
16.11.2018 | NASA/Goddard Space Flight Center

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: UNH scientists help provide first-ever views of elusive energy explosion

Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.

Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

European Space Talks: Weltraumschrott – eine Gefahr für die Gesellschaft?

23.10.2018 | Event News

 
Latest News

Purdue cancer identity technology makes it easier to find a tumor's 'address'

16.11.2018 | Health and Medicine

Good preparation is half the digestion

16.11.2018 | Life Sciences

Microscope measures muscle weakness

16.11.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>