Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Quantum Simulator for Complex Electronic Materials

05.12.2008
Researchers from MPQ, Mainz, Cologne and Jülich simulate complex electronic insulator with ultracold atoms in artificial crystals of light

The design of new materials with specific properties is a difficult and important challenge in physics and chemistry. Nobel Prize winner Richard P. Feynman in 1982 therefore suggested to build a "quantum simulator" in order to understand and predict the properties of complex materials by simulating them using an artificial, but highly controllable different quantum system. In the latest issue of the journal Science a team of scientists led by Prof. Immanuel Bloch, director at MPQ and chair of physics at the Johannes Gutenberg Universität of Mainz show how to simulate the properties of electrons in a real crystal by using ultracold atoms trapped in an artificial crystal formed by interfering laser beams - a so called optical lattice. The researchers from the University of Mainz, the University of Cologne and the Forschungszentrum Jülich succeeded in demonstrating one of the most dramatic effects of the electron-electron repulsion: When the interactions between the electrons get too strong, a metal can suddenly become insulating. The resulting so-called Mott-insulator is probably the most important example of a strongly correlated state in condensed matter physics, and it is a natural starting point for the investigation of quantum magnetism. In addition, high temperature superconductivity is found to arise in close proximity to it.


An artists impression of the fermionic Mott insulating state: Due to the dominating repulsive interaction every lattice site is occupied by exactly one atom. The different colors indicate different spin states. Universität Mainz

"Atoms in an optical lattice are a nearly perfect quantum simulator for electrons in a solid, as they offer a very flexible model-system in a clean and well-controlled environment" explains Ulrich Schneider from the University of Mainz. Investigating complex materials and high temperature superconductors is difficult because of the presence of disorder and many competing interactions in the real crystalline materials. "This makes it difficult to identify the role of specific interactions and, in particular, to decide whether repulsive interactions between fermions alone can explain high temperature superconductivity" says Prof. Bloch.

In the experiment, a gas of potassium atoms is first cooled down to almost zero temperature. Subsequently, an optical lattice is created by overlapping several laser beams. To the atoms, the resulting standing-wave laser field appears as a regular crystal of tens of thousands of individual micro-traps, similar to an array of optical tweezers. The ultracold atoms, which assume the role of electrons in real solids, will line up at the nodes of this standing-wave field.

By investigating the behaviour of the atoms under compression and increasing interaction strength, and thereby measuring their compressibility, the experimentalists have been able to controllably switch the system between metallic and insulating states of matter and find evidence for a Mott-insulating phase within the quantum gas of fermionic atoms. In such a Mott insulating phase, the repulsive interactions between the atoms force them to order one-by-one into the regular lattice structure.

The observation of the fermionic Mott-insulator in the context of optical lattices opens up a new possibility to simulate and study strongly correlated states and related phenomena. This is affirmed by the excellent agreement achieved in comparing the experiment with theoretical calculations of modern condensed matter theory performed in Cologne and Jülich, which included extensive simulations on the Jülich based supercomputer system JUGENE. [I.B.]

Original publication:

U. Schneider, L. Hackermüller, S. Will, Th. Best, and I. Bloch,
T.A. Costi, R.W. Helmes, D. Rasch, and A. Rosch
"Metallic and Insulating Phases of Repulsively Interacting Fermions in a 3D Optical Lattice"

Science, 5th December 2008

More information and picture gallery:
www.quantum.physik.uni-mainz.de/bec
Contact:
Prof. Dr. Immanuel Bloch
Max-Planck-Institut für Quantenoptik
Hans-Kopfermann-Str. 1
D-85748 Garching, Deutschland
Phone: (+ 49 89) 32905 - 238
Fax: (+ 49 89) 32905 - 760
E-mail: immanuel.bloch[a]
Johannes Gutenberg-Universität Mainz
Staudingerweg 7
D 55128 Mainz
Phone: (+49 6131) 39-26234 / 22279
Fax: (+49 6131) 39-25179
E-mail: Bloch[a]Uni-Mainz.DE

Dr. Olivia Meyer-Streng | idw
Further information:
http://www.quantum.physik.uni-mainz.de
http://www.mpq.mpg.de
http://www.uni-mainz.de

More articles from Physics and Astronomy:

nachricht Engineering team images tiny quasicrystals as they form
18.08.2017 | Cornell University

nachricht Astrophysicists explain the mysterious behavior of cosmic rays
18.08.2017 | Moscow Institute of Physics and Technology

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: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

Nagoya physicists resolve long-standing mystery of structure-less transition

21.08.2017 | Materials Sciences

Chronic stress induces fatal organ dysfunctions via a new neural circuit

21.08.2017 | Health and Medicine

Scientists from the MSU studied new liquid-crystalline photochrom

21.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>