Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Bosons crystallize in 2-D traps

03.12.2004


Theoretical simulations of six harmonically trapped bosons. See footnote for details on each graph.


Researchers at the Georgia Institute of Technology have unveiled a fundamental change in the properties of matter. The theoretical finding, that bosons placed in two-dimensional harmonic traps will crystallize when the strength of their repulsive interactions is increased, appears in the December 3 issue of the journal Physical Review Letters (volume 93, article 230405, 2004).

One of two categories of elementary particles, bosons typically form cloudy aggregates called Bose-Einstein condensates when cooled to temperatures near absolute zero. In the condensate, the particles may be pictured as sitting on top of one another, occupying the same space. But that’s only when their interactions are relatively weak, said Uzi Landman, director of the Center for Computational Materials Science, Regents’ professor and Callaway chair of physics at Georgia Tech.

"When the repulsive interaction between the bosons is increased, they separate and instead of forming a condensate they crystallize, acting more like their counterpart fermions. Experimentally, such behavior was shown this year to happen in one-dimension, now we predicted theoretically that it will happen in two-dimensions. Furthermore, through a straightforward extension of our method one could easily extend it to three-dimensions,” he said.



In quantum physics, all elementary particles such as quarks, electrons and gluons are classified as either fermions or bosons, depending on their spin. The spin of bosons takes integer values and fermions have half-integer values of their spin. Electrons and quarks –two examples of fermions – are the basic building blocks of matter, while bosons such as photons and gluons govern the fundamental forces of nature such as electromagnetism.

In 1960 it was theoretically predicted by Marvin Girardeau, now at the University of Arizona, that in one-dimensional space, bosons would act more like fermions and form a lattice if their repulsion became sufficiently strong. It took more than 40 years for experimental physicists to test the theory, but recently two different groups of scientists published articles in Science and Nature verifying the theory, using experiments carried out on trapped bosons.

Now, Landman, his colleague Constantine Yannouleas, and graduate student Igor Romanovsky, discovered, through theoretical modeling involving computer-based simulations of up to seven bosons in a harmonic two-dimensional trap, that instead of clumping together to form Bose-Einstein condensates, the bosons localize in space forming polygonal crystals. For example, six bosons crystallize into a two-dimensional pentagon-shaped crystal with one boson in the center. “The forces between the bosons are repulsive,” said Landman. “The trap is the only thing holding them together. As soon as you release the trap, the crystal goes away.”

Landman and Yannouleas do not think that it will take another 40 years for experimental physicists to test the theoretical prediction. “Now that people know how to make Bose-Einstein condensates, use traps, and vary the strength of the interactions, testing could be done faster,” Landman explained.

As for potential applications of this research, Landman notes that “the main merit of this research is in increasing our fundamental understanding of nature and of the processes underlying physical behavior under certain extreme conditions”. “Nevertheless,” he adds, “out of such basic scientific contributions other things may develop, for example in the area of quantum computing – you just have to wait and see.”

In the 1920s Indian physicist Satyendra Nath Bose and Albert Einstein predicted that atoms cooled to temperatures close to absolute zero would collapse to their lowest quantum state, forming a state of matter that became known as the Bose-Einstein condensate. It wasn’t until 1995 that physicists in Boulder, Colorado, and at MIT were successful in creating the condensate. And in 2001, Eric Cornell, Wolfgang Ketterle and Carl Wieman were awarded the Nobel Prize in Physics for this achievement.

Graph Captions

Theoretical simulations of six harmonically trapped bosons.

(a) The density of a Bose-Einstein condensate formed for weak repulsive interactions.

(b) The density distribution of the symmetry-broken crystalline solution that is predicted to form for stronger repulsive interactions.

(c) Density distribution of the symmetry-restored state, showing overall circular symmetry.

(d) Conditional probability map, with the reference point located on one of crystalline sites (marked by a black dot), illustrating a predicted pentagonal lattice with one boson at the center. Distances are in units of L0 which is determined by the characteristic harmonic frequency of the trap, and the effective mass of the bosons.

David Terraso | EurekAlert!
Further information:
http://www.icpa.gatech.edu

More articles from Physics and Astronomy:

nachricht First Juno science results supported by University of Leicester's Jupiter 'forecast'
26.05.2017 | University of Leicester

nachricht Measured for the first time: Direction of light waves changed by quantum effect
24.05.2017 | Vienna University of 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: Can the immune system be boosted against Staphylococcus aureus by delivery of messenger RNA?

Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.

Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

How herpesviruses win the footrace against the immune system

26.05.2017 | Life Sciences

Water forms 'spine of hydration' around DNA, group finds

26.05.2017 | Life Sciences

First Juno science results supported by University of Leicester's Jupiter 'forecast'

26.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>