If two children splash in the sea high water waves will emerge due to constructive superposition. Different observations are made for the microscopic world in an experiment at the University of Bonn, where physicists used a laser beam to generate light waves from two cesium atoms. The light waves were reflected back from two parallel mirrors. It turned out that this experimental arrangement suppressed the emergence of high light waves. With their results, which are published now in the „Physical Review Letters“, the scientists observed the most fundamental scenario of light-matter interaction with two atoms.
The physicists at the University of Bonn confined two levitating cesium atoms in a light cage for photons. A laser beam continuously irradiated the two atoms, which scattered the laser light similar to levitating dust in a sunbeam. The scattered light waves superimpose and were reflected back onto the atoms by two parallel mirrors.
“We expected that two atoms in such a cage would behave differently from a single atom” says first author Dr. René Reimann, colleague of Prof. Dr. Dieter Meschede at the “Institut für Angewandte Physik”, University of Bonn. This matches with our everyday experience: Two splashing children in the sea produce different water waves than a single child. However, for the light cage with the light waves emitted from the two atoms the analogy to the splashing children in the sea does not fully hold. Here no high light waves are observed.
Backaction suppresses high light waves
The surprising situation of the two atoms inside the light cage can be illustrated with two children in a swimming pool instead of the sea. Here the children create water waves that are partially reflected from the pool edge. Now the reflected waves and the forward running waves cancel each other. “Due to this feedback two children can in the best case generate barely higher waves than a single child”. Albeit by changing the distance between them, the kids in the pool can change the height of the water waves.
Keeping this in mind one can understand the situation of the two cesium atoms in the experiment: Even in the best case when the light waves of the two atoms constructively interfere barely more photons could be counted compared to the one atom case. “It became clear that the mirrors introduce a strong backaction that hinders the emergence of high light waves”, describes Dieter Meschede.
New insights in light-matter interaction
Nevertheless minimal position changes of the levitating cesium atoms in the light cage can be detected through distinct changes in the height of the superimposed light waves. “Up to now this was not possible. Now, this opens up new insights and experimental possibilities for the light-atom interaction of two-atom systems”, says René Reimann. These new possibilities could support forward-looking technologies like quantum memories and quantum networks for telecommunication and computation.
So far, international teams of scientists observed the interaction of a single or many atoms with photons in a light cage. For his fundamental contributions to this research, Serge Haroche was awarded the Nobel Prize in physics in 2012. Now, the physicists from Bonn achieved to observe the interaction of exactly two atoms in a light cage. “With this experiment the most fundamental case of collective light-matter interaction has been realized”, says Dieter Meschede.
The research group “Quantum Technologies” at the University of Bonn experimentally investigates the controlled interaction between atoms and light. The group is focusing on the generation of particular quantum mechanical states.
Publication: R. Reimann, W. Alt, T. Kampschulte, T. Macha, L. Ratschbacher, N. Thau, S. Yoon, D. Meschede, Cavity-Modified Collective Rayleigh Scattering of Two Atoms, Physical Review Letters, DOI: 10.1103/PhysRevLett.114.023601
Contact information for media:
Dr. René Reimann
Institut für Angewandte Physik
Prof. Dr. Dieter Meschede
Institut für Angewandte Physik
Johannes Seiler | idw - Informationsdienst Wissenschaft
Riddle of matter remains unsolved: Proton and antiproton share fundamental properties
19.10.2017 | Johannes Gutenberg-Universität Mainz
Space radiation won't stop NASA's human exploration
18.10.2017 | NASA/Johnson Space Center
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
19.10.2017 | Life Sciences
19.10.2017 | Interdisciplinary Research
19.10.2017 | Earth Sciences