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 Magnetic moment of a single antiproton determined with greatest precision ever
19.01.2017 | Johannes Gutenberg-Universität Mainz

nachricht Traffic jam in empty space
19.01.2017 | Universität Konstanz

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: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

The Great Unknown: Risk-Taking Behavior in Adolescents

19.01.2017 | Studies and Analyses

Magnetic moment of a single antiproton determined with greatest precision ever

19.01.2017 | Physics and Astronomy

CRISPR meets single-cell sequencing in new screening method

19.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>