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
Observations of nearby supernova and associated jet cocoon provide new insights on gamma-ray bursts
18.01.2019 | George Washington University
A new twist on a mesmerizing story
17.01.2019 | ETH Zurich Department of Physics
The scientific and political community alike stress the importance of German Antarctic research
Joint Press Release from the BMBF and AWI
The Antarctic is a frigid continent south of the Antarctic Circle, where researchers are the only inhabitants. Despite the hostile conditions, here the Alfred...
World first experiments on sensor that may revolutionise everything from medical devices to unmanned vehicles
The new sensor - capable of detecting vibrations of living cells - may revolutionise everything from medical devices to unmanned vehicles.
Dead and alive at the same time? Researchers at the Max Planck Institute of Quantum Optics have implemented Erwin Schrödinger’s paradoxical gedanken experiment employing an entangled atom-light state.
In 1935 Erwin Schrödinger formulated a thought experiment designed to capture the paradoxical nature of quantum physics. The crucial element of this gedanken...
Cellulose obtained from wood has amazing material properties. Empa researchers are now equipping the biodegradable material with additional functionalities to produce implants for cartilage diseases using 3D printing.
It all starts with an ear. Empa researcher Michael Hausmann removes the object shaped like a human ear from the 3D printer and explains:
The phenomenon of so-called superlubricity is known, but so far the explanation at the atomic level has been missing: for example, how does extremely low friction occur in bearings? Researchers from the Fraunhofer Institutes IWM and IWS jointly deciphered a universal mechanism of superlubricity for certain diamond-like carbon layers in combination with organic lubricants. Based on this knowledge, it is now possible to formulate design rules for supra lubricating layer-lubricant combinations. The results are presented in an article in Nature Communications, volume 10.
One of the most important prerequisites for sustainable and environmentally friendly mobility is minimizing friction. Research and industry have been dedicated...
16.01.2019 | Event News
14.01.2019 | Event News
12.12.2018 | Event News
18.01.2019 | Materials Sciences
18.01.2019 | Life Sciences
18.01.2019 | Health and Medicine