Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Ultra-cold temperature physics opens way to understanding and applications

22.02.2005


Researchers doing ultra-cold temperature physics may not have to wear parkas, but they are producing the coldest temperatures ever and exploring model quantum systems that might lead to more accurate clocks and gyroscopes, quantum computers and communications as well as a better understanding of quantum physics phenomena.



Nearly 80 years ago, Albert Einstein and Satyendra Nath Bose predicted that gases of atoms cooled down very close to absolute zero would behave in unison. In 1995, three laboratories produced such Bose-Einstein condensates and opened the door for investigation of physical properties of atoms on a very cold scale.

David S. Weiss, associate professor of physics, Penn State, described recent research in one-dimensional quantum systems at the annual meeting of the American Association for the Advancement of Science today (Feb. 20) in Washington, D.C. "These ultra-cold atoms can act as model systems to help us understand other quantum systems," says Weiss. "Their interactions can be calculated and controlled very accurately."


In a Bose-Einstein condensate, alkali metal atoms are cooled using lasers and a form of evaporation until they are a hair above absolute zero. Bosons, a class of particles that prefer to share the same energy state, when cooled this cold, begin to act in unison. The atoms’ wave functions -- the description of each atom’s position and momentum – all become identical. Initially, Bose-Einstein condensates were confined in featureless magnetic traps, but researchers have taken the experiments further. "By putting Bose-condensed atoms into versatile light traps, we can make atomic wave functions exhibit remarkable behavior," says Weiss. "Most known quantum phenomena can be studied clearly with ultra-cold atoms, and as yet unknown phenomena can be conceived and observed."

The traps Weiss refers to are light traps created by lasers. By reflecting laser light back on itself, researchers create unmoving standing waves that, if created in a three-dimensional grid, can trap atoms. When this type of grid is superimposed over a Bose-Einstein condensate, the atoms segregate into individual traps, creating a matrix of tiny cells with ultra-cold atoms inside. Turning the lattice on and off can switch the system from a superfluid to something called a Mott insulator and back to a superfluid. Superfluids and Mott insulators have different quantum characteristics.

Weiss, who is using rubidium 87, takes the grid one step further and creates a one-dimensional Tonks-Girardeau gas. By constraining the grid in two directions so that movement is only possible in one dimension, as if the atom were on a wire, Weiss creates a system where the bosons – rubidium 87 atoms – act like fermions.

Fermions, unlike bosons, do not like to share energy states. Even near zero temperature, they avoid each other. In superconductivity, fermions act like bosons. In a Tonks-Girardeau gas, strongly interacting bosons act as non-interacting fermions. "A one-dimensional Tonks-Girardeau gas is one of very few many-particle systems that can be exactly solved mathematically," says Weiss. "This was done in the ’60s, but there had been no experimental system."

Now, Weiss can experimentally verify the mathematical calculations. Using these techniques, researchers may be able to understand superconductivity better, form quantum molecules and perhaps eventually create quantum computers.

Along with rubidium, some other potential elements for Bose-Einstein condensates and ultra-cold quantum physics are sodium, cesium, lithium and ytterbium.

Weiss considers quantum computing a promising way to use ultra cold atoms. The atoms can act as quantum bits, or qubits, with internal sub-states functioning as the ubiquitous 0 and 1s of computing.

"However, quantum computers can only do a certain class of calculations, factoring large numbers for example," says Weiss. "They might also be used to simulate other quantum mechanical systems, answering questions that are simply not answerable with any conceivable classic computer."

Superfluid clouds of atoms and grid-constrained super cold atoms are not the only possibilities researchers are exploring in ultra cold quantum physics. Other related areas of research include lattices of atomic vortices, coherent quantum chemistry and atomic interferometry.

A’ndrea Elyse Messer | EurekAlert!
Further information:
http://www.psu.edu

More articles from Physics and Astronomy:

nachricht NASA detects solar flare pulses at Sun and Earth
17.11.2017 | NASA/Goddard Space Flight Center

nachricht Pluto's hydrocarbon haze keeps dwarf planet colder than expected
16.11.2017 | University of California - Santa Cruz

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: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

NASA detects solar flare pulses at Sun and Earth

17.11.2017 | Physics and Astronomy

NIST scientists discover how to switch liver cancer cell growth from 2-D to 3-D structures

17.11.2017 | Health and Medicine

The importance of biodiversity in forests could increase due to climate change

17.11.2017 | Studies and Analyses

VideoLinks
B2B-VideoLinks
More VideoLinks >>>