Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Closing in on the Phenomenon of Superconductivity With a Two-dimensional Atomic Gas

09.06.2015

Transition into superfluid phase: Heidelberg physicists characterise an exotic quantum superfluid

Using an exotic quantum superfluid that originates in a two-dimensional atomic gas, researchers from Heidelberg University are closing in on the phenomenon of superconductivity. The team headed by Prof. Dr. Selim Jochim of the Institute for Physics is using this special gas as a model system to more easily study the largely unknown mechanism of the superfluid phase transition in 2D structures.


Experimental setup to generate a two-dimensional ultracold quantum gas

In the background is the vacuum chamber in which the researchers prepared the quantum superfluid. The mirrors and lenses needed to create the laser trap are seen in the foreground. This apparatus allows the physicists to generate a two-dimensional ultracold gas every 15 seconds and then measure its properties. Photo: Martin Ries


Atomic gas in a magneto-optical trap

The luminous red cloud suspended in the centre of the vacuum chamber consists of approximately one billion lithium atoms. Their temperature is about 500 microkelvins, or about 500 millionths of a degree above absolute zero at negative 273.15 degrees Celsius. The atoms are captured by laser beams, cooled, and used as the foundation for all the experiments conducted by Prof. Dr. Selim Jochim’s team. Photo: Martin Ries

The researchers hope to gain new insight into the so-called room-temperature superconductor, a hypothetical material that does not require cooling to achieve lossless conduction of electricity. The research results were published in the journal “Physical Review Letters”.

Two of the most impressive phenomena that exhibit quantum mechanical behaviour in the “normal” world are superfluidity and its by-product, superconductivity. In physics, superfluidity is a state of matter in which a fluid loses all internal resistance.

Superconductivity results when the electrons in a material behave like a superfluid liquid. They flow without encountering any friction, and the electrical resistance drops to zero. This state occurs only below a certain critical temperature, which is different for every superconductor.

This behaviour is well understood in the conventional superconductor, in which the electrons move in three dimensions. But the problem is that the superconducting state can only be achieved at very cold temperatures well under negative 200 degrees Celsius. The necessary extensive cooling hampers a technological application, according to physicist Dr. Martin Ries.

“For several years, it has been possible to produce high-temperature superconductors. Their critical temperature is significantly higher, but unfortunately still just under negative 130 degrees Celsius. Additionally, we only have a partial understanding of the way they work, making it difficult to develop better superconductors of this kind,” says the scientist, who is a member of Prof. Jochim’s research team.

As Dr. Ries explains, science assumes that electrons can only move in two dimensions in high-temperature superconductors. So the Heidelberg physicists focused their research into superfluidity and superconductivity on two-dimensional structures. The superfluid transition is quite different between 2D and 3D structures, and the two-dimensional transition mechanism remains largely a mystery that is difficult to pin down theoretically.

Although the so-called BKT theory did address it in the 1970s, it is only valid if the forces between the electrons are weak. “But what exactly happens with stronger forces is not known, and that is precisely the scenario of major significance,” says Dr. Ries.

Jochim’s team of physicists has now succeeded in building a simple model system to perform a quantum simulation of the superfluid phase transition in 2D structures. They are using a two-dimensional ultracold gas captured in a laser trap. “We are able to create a ‘clean’ system that is easier to understand and in which the quantum mechanical behaviour of the particles resembles that of the electrons in two-dimensional structures,” reports Dr. Ries.

It actually allowed the researchers to observe the transition into the superfluid phase at low temperatures and measure the critical temperature for any strength of interparticle forces. “This gives us the ability to more easily test the various theories for 2D superfluidity in the future,” explains Prof. Jochim, whose team is currently investigating the correlations in the superfluid phase. “Over the long term, we hope to gain a better understanding of high-temperature superconductivity that could lead to the development of a room-temperature superconductor at some point in the future.”

This research was conducted by a cooperation of experimental and theoretical physicists at Heidelberg University's Center for Quantum Dynamics. For their article published in the “Physical Review Letters”, the authors received the coveted “Editors’ Suggestion” distinction.

Original publication:
M.G. Ries, A.N. Wenz, G. Zürn, L. Bayha, I. Boettcher, D. Kedar, P.A. Murthy, M. Neidig, T. Lompe and S. Jochim: Observation of Pair Condensation in the Quasi-2D BEC-BCS Crossover. Physical Review Letters 114, 230401 (8 June 2015), doi: 10.1103/PhysRevLett.114.230401

Contact:
Dr. Martin Ries
Institute for Physics
Phone: +49 6221 54-19484
martin.ries@physi.uni-heidelberg.de

Communications and Marketing
Press Office, phone: +49 6221 54-2311
presse@rektorat.uni-heidelberg.de

Weitere Informationen:

h

Marietta Fuhrmann-Koch | idw - Informationsdienst Wissenschaft

More articles from Physics and Astronomy:

nachricht Smooth propagation of spin waves using gold
26.06.2017 | Toyohashi University of Technology

nachricht A 100-year-old physics problem has been solved at EPFL
23.06.2017 | Ecole Polytechnique Fédérale de Lausanne

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: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Study shines light on brain cells that coordinate movement

26.06.2017 | Life Sciences

Smooth propagation of spin waves using gold

26.06.2017 | Physics and Astronomy

Switchable DNA mini-machines store information

26.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>