Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Long-range tunneling of quantum particles

13.06.2014

The quantum tunnel effect manifests itself in a multitude of well-known phenomena.

Experimental physicists in Innsbruck, Austria, have now directly observed quantum particles transmitting through a whole series of up to five potential barriers under conditions where a single particle could not do the move.


Quantum particles transmit through a whole series of barriers under conditions where a single particle could not do the move. Illustration: Uni Innsbruck

One of the most remarkable consequences of the rules in quantum mechanics is the capability of a quantum particle to penetrate through a potential barrier even though its energy would not allow for the corresponding classical trajectory. This is known as the quantum tunnel effect and manifests itself in a multitude of well-known phenomena.

For example, it explains nuclear radioactive decay, fusion reactions in the interior of stars, and electron transport through quantum dots. Tunneling also is at the heart of many technical applications, for instance it allows for imaging of surfaces on the atomic length scale in scanning tunneling microscopes.

All the above systems have in common that they essentially represent the very fundamental paradigm of the tunnel effect: a single particle that penetrates through a single barrier. Now, the team of Hanns-Christoph Nägerl, Institute for Experimental Physics of the University of Innsbruck, Austria, has directly observed tunneling dynamics in a much more intriguing system:

They see quantum particles transmitting through a whole series of up to five potential barriers under conditions where a single particle could not do the move. Instead the particles need to help each other via their strong mutual interactions and via an effect known as Bose enhancement.

In their experiment the scientists place a gas of Cesium atoms at extremely low temperatures just above absolute zero temperature into a potential landscape that is deliberately engineered by laser light. This so-called optical lattice forms a regular and perfect structure constituting the multiple tunneling barriers, similar to a washboard.

As temperatures are so low and thus the atoms’ kinetic energies are so tiny, the only way to move across the washboard is via tunneling through the barriers. The tunneling motion is initiated by applying a directed force onto the atoms along one of the lattice axes, that is, by tilting the washboard.

It is now one of the crucial points in the experiment that the physicists control through how many barriers the particles penetrate by the interplay between the interaction and the strength of the force in conjunction with Bose enhancement as a result of the particles’ quantum indistinguishability.

Very similar to a massive object moving in the earth’s gravitational field, the tunneling atoms should loose potential energy when they move down the washboard. But where can they deposit this energy in such a perfect and frictionless environment?

It’s the interaction energy between the atoms when they share the same site of the lattice that compensates for the potential energy. As a result, the physicists found that the tunneling motion leads to discrete resonances corresponding to the number of barriers the particles penetrate through.

It is left for the future to explore the role of such long-range tunneling processes for lattice systems with ultracold atoms in the context of quantum simulation and quantum information processing, or for different physical settings, for instance electronic quantum devices, molecular or even biological systems.

Publication: Observation of many-body dynamics in long-range tunneling after a quantum quench. Florian Meinert, Manfred J. Mark, Emil Kirilov, Katharina Lauber, Philipp Weinmann, Michael Gröbner, Andrew J. Daley, Hanns-Christoph Nägerl. Science 2014 DOI: 10.1126/science.1248402 (arXiv:1312.2758)

Contact
Univ.-Prof. Dr. Hanns-Christoph Nägerl
Institute for Experimental Physics
University of Innsbruck
phone: +43 512 507 52420
email: christoph.naegerl@uibk.ac.at

Christian Flatz
Public Relations
University of Innsbruck
phone: +43 512 507 32022
email: christian.flatz@uibk.ac.at

Weitere Informationen:

http://dx.doi.org/10.1126/science.1248402 - Observation of many-body dynamics in long-range tunneling after a quantum quench. Florian Meinert, Manfred J. Mark, Emil Kirilov, Katharina Lauber, Philipp Weinmann, Michael Gröbner, Andrew J. Daley, Hanns-Christoph Nägerl. Science 2014

Dr. Christian Flatz | Universität Innsbruck
Further information:
http://www.uibk.ac.at

More articles from Physics and Astronomy:

nachricht Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics

nachricht What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin

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: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>