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 New type of smart windows use liquid to switch from clear to reflective
14.12.2017 | The Optical Society

nachricht New ultra-thin diamond membrane is a radiobiologist's best friend
14.12.2017 | American Institute of Physics

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: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Plasmonic biosensors enable development of new easy-to-use health tests

14.12.2017 | Health and Medicine

New type of smart windows use liquid to switch from clear to reflective

14.12.2017 | Physics and Astronomy

BigH1 -- The key histone for male fertility

14.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>