Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

What Are The Special Properties Of An Atomic Gas?

28.01.2016

Heidelberg physicists determine equation of state – basis for understanding superconductivity

In a laboratory experiment, physicists at the Center for Quantum Dynamics of Heidelberg University have succeeded in determining the equation of state for an atomic gas, which can be used to precisely describe the thermodynamic properties of this physical system.


Fig.: Puneet Murthy

In a gas of ultracold lithium atoms, identical particles repel each other by the rules of quantum mechanics, while unlike atoms can attract each other and form molecules. Theoretical physicists around Dr. Tilman Enss have now determined the equation of state, i.e., how the attraction changes the density of the quantum gas, from an experiment in the group of Prof. Selim Jochim in Heidelberg.

According to Associate professor Dr. Tilman Enss and Prof. Dr. Selim Jochim, the equation lays the foundation for further experiments using ultracold atoms to better understand the mechanisms of superconductivity, i.e., the lossless conduction of electricity. The results of their research were published in the journal “Physical Review Letters”.

“Everyone knows how air becomes thinner as you climb a mountain. In physics this effect is described by an equation of state, which in this instance determines how the density of air changes in relation to the distance from the Earth,” explains Dr. Enss of the Institute for Theoretical Physics.

“The same principle applies in many areas of physics – from the distribution of matter in the structure of stars to atomic gases, which we were recently able to manufacture in the laboratory,” says Prof. Jochim, a researcher at the Institute for Physics. At the Center for Quantum Dynamics, the researchers have combined Dr. Enss’ theoretical calculations with the findings from Prof. Jochim’s experiments. Their investigation focused on an atomic gas cooled to a temperature near absolute zero.

Physicists find ultracold atomic gases so interesting because the quantum physical effects are clearly evident at extremely low temperatures. In a certain type of particle – the fermion – two atoms can never assume the same state or occupy the same space.

“The fermions exert pressure on similar types of particles and push them aside so that the density in an atomic cloud can never become too great,” explains Prof. Jochim, whose experimental working group observed this effect using lithium atoms. The pressure between the fermions causes the atomic cloud to thin and spread out.

Researchers in theoretical physics have long been interested in how the density of gas changes when fermions also attract. This counteracts the pressure of the fermions and brings the particles closer together.

“If there is sufficient attraction between two fermions, they form a pair. According to the laws of quantum physics, these types of molecules can get closer together than the original fermions. Exactly how this happens in particles that move in a single plane is currently an important question,” explains Dr. Enss. The atomic gases are of great interest for research because they have many universal properties that are found in completely different physical situations. The equation of state of an atomic gas, for example, can be used to draw conclusions about the structure of certain stars.

Ultracold atoms are especially good in experiments for measuring how the equation of state relates to particle attraction. Practically any strength of attraction can be artificially created in ultracold atoms. Prof. Jochim and his research group observed that a strong attraction in the centre of the atomic cloud formed a denser nucleus.

Theoretical physicists Dr. Enss and Dr. Igor Boettcher have now reconstructed the equation of state by analysing the experimental data, thereby confirming their own theoretical predictions. The researchers are particularly interested in atoms that move in one plane.

The atomic gas then exhibits a similarity to layered materials that are superconducting even at a relatively high temperature. According to the Heidelberg researchers, the equation of state determined can now be used as a basis for future experiments to better understand the mechanisms of high-temperature superconductivity.

For their article published in the “Physical Review Letters”, the Heidelberg researchers received the “Editors’ Suggestion” distinction. It also was highlighted in a “Viewpoint” in the magazine “Physics”.

Original publication:
I. Boettcher, L. Bayha, D. Kedar, P. A. Murthy, M. Neidig, M. G. Ries, A. N. Wenz, G. Zürn, S. Jochim, and T. Enss: Equation of state of ultracold fermions in the 2D BEC-BCS crossover region, Physical Review Letters (published online on 27 November 2016), doi: 10.1103/ PhysRevLett.116.045303

Contact:
Assoc. Prof. Dr. Tilman Enss
Institute for Theoretical Physics
Phone +49 6221 54-9337
enss@thphys.uni-heidelberg.de

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

Marietta Fuhrmann-Koch | idw - Informationsdienst Wissenschaft
Further information:
http://www.uni-heidelberg.de

More articles from Physics and Astronomy:

nachricht One-way roads for spin currents
23.05.2018 | Singapore University of Technology and Design

nachricht Tunable diamond string may hold key to quantum memory
23.05.2018 | Harvard John A. Paulson School of Engineering and Applied Sciences

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: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

Im Focus: Entangled atoms shine in unison

A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.

The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

Research reveals how order first appears in liquid crystals

23.05.2018 | Life Sciences

Space-like gravity weakens biochemical signals in muscle formation

23.05.2018 | Life Sciences

NIST puts the optical microscope under the microscope to achieve atomic accuracy

23.05.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>