Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

UA Scientists Discover Quantum Mechanical 'Hurricanes' Form Spontaneously

16.10.2008
University of Arizona scientists experimenting with some of the coldest gases in the universe have discovered that when atoms in the gas get cold enough, they can spontaneously spin up into what might be described as quantum mechanical twisters or hurricanes.

The surprising experimental results agree with independent numerical simulations produced by collaborating scientists at the University of Queensland in Australia. The UA and Australian researchers are reporting the results of the research in Oct. 16 issue of the journal Nature.

The results are of great interest because they reveal something fundamentally new about certain kinds of "phase transitions," and nature is replete with phase transitions.

Common phase transitions include liquid water freezing to ice, or liquid water boiling to steam. Another common phase transition occurs in proteins when raw eggs are cooked. More exotic examples of phase transitions include the cooling of materials until they become superconductors, and, on the scale of the universe, the phase transition that transformed the early universe from a hot, dense system born from the Big Bang into the universe with protons, electrons, structure and forces observed today.

A group of UA scientists headed by optical sciences associate professor Brian P.
Anderson uses lasers and magnetic fields to trap gases of rubidium atoms and cool them to temperatures of about 50 billionths of a degree Kelvin, which is close to minus 460 degrees Fahrenheit. This temperature is about as close as scientists have ever been to reaching absolute zero, the hypothetical temperature at which all molecular activity ceases.

By first creating such a cold gas in their UA campus laboratory, and then lowering the temperature of the system just a little bit more, some atoms in the gas still behave much as they do in classical physics, bouncing around at random. However, this additional cooling induces a phase transition where other atoms of the gas become a new form of matter called a Bose-Einstein condensate, a tiny droplet of superfluid which behaves according to quantum physics.

Bose-Einstein condensates, or BECs, were first produced in Nobel Prize-winning experiments in 1995. Since then, theoretical and experimental researchers have studied BECs intensely, using BECs as valuable new tools for probing a wide range of fundamental physics. The UA experimental team, and the University of Queensland theoretical team headed by physicist Matthew Davis, paired up to push the limits of what is known about how BECs actually form.

"Scientists understand a lot more about BECs after over ten years of work, but there are still some great surprises," said Anderson.

Their work lends additional support to the idea that spontaneous "topological defect" formation in phase transitions is a widespread phenomenon, even at temperatures near absolute zero. "Defect" in this sense means that a discontinuity has appeared in the background superfluid of the BEC.

"In our experiments, we found that when we cool a very cold gas through the BEC phase transition, the BEC can spontaneously begin to rotate, creating something like a microscopic quantum mechanical hurricane where atoms rotate as a fluid around a vortex core where there is no fluid," Anderson said.

"The idea of spontaneous formation of vortices in BECs had been lightly discussed as theory before, but had not been observed in experiments," he added.

Ironically, showing that BECs could be spun up into a rotating state to form vortices was a hot research topic just a few years ago. Anderson was a postdoc on the team that was the first to create a vortex in a BEC. They used creative but relatively difficult techniques. Other groups have now used a variety of techniques to successfully create BECs with many vortices.

"What was so surprising about our work is that we saw these things just appear by themselves. You just make your condensate, and they sometimes appear. You don't have to somehow manipulate your system, all you have to do is cool through the phase transition."

" I think what we've done, for the first time, is link experimental observations of defect formation in a phase transition with a theoretical model and numerical simulations that are built on some pretty rigid foundations of quantum mechanics and quantum interactions," Anderson said.

"By collaborating with our colleagues in Australia, who are doing the theoretical research, we can back out details of the physical process that causes these vortices to spontaneously form. It will help us understand more about how superfluids develop, and perhaps more about universal phase transition dynamics in general, including the kind of phase transition that occurred in the early universe."

The experimental research was supported by grants from the National Science Foundation and the Army Research Office. The theoretical work was supported by the Australian Research Council and the University of Queensland.

The UA and University of Queensland science results agree with an important theoretical model called the "Kibble-Zurek mechanism" that concerns how defects can form in a phase transition. The model says that the faster a system undergoes a phase transition, the more defects -- in this case, the vortices -- naturally and spontaneously form. Conversely, the slower the system is cooled, the smoother the phase transition into a new state will be and the fewer defects will appear.

In the not-so-near future, Anderson said, BECs may become useful in devices in ways similar to laser light. Rotation sensors, accelerometers or interferometers based on the coherence properties of Bose-Einstein condensates are among the envisioned possible applications, he said.

But for now, perhaps most exciting use for BECs is as a tool for exploring the fundamental ideas of physics in ways that couldn't be explored before.

SCIENCE CONTACT:
Brian P. Anderson (520-626-5825; bpa@optics.arizona.edu)

Lori Stiles | University of Arizona
Further information:
http://www.optics.arizona.edu/anderson
http://www.arizona.edu

Further reports about: BEC Hurricanes Quantum Universe coldest gas magnetic field

More articles from Earth Sciences:

nachricht Geophysicists and atmospheric scientists partner to track typhoons' seismic footprints
16.02.2018 | Princeton University

nachricht NASA finds strongest storms in weakening Tropical Cyclone Sanba
15.02.2018 | NASA/Goddard Space Flight Center

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

Im Focus: Autonomous 3D scanner supports individual manufacturing processes

Let’s say the armrest is broken in your vintage car. As things stand, you would need a lot of luck and persistence to find the right spare part. But in the world of Industrie 4.0 and production with batch sizes of one, you can simply scan the armrest and print it out. This is made possible by the first ever 3D scanner capable of working autonomously and in real time. The autonomous scanning system will be on display at the Hannover Messe Preview on February 6 and at the Hannover Messe proper from April 23 to 27, 2018 (Hall 6, Booth A30).

Part of the charm of vintage cars is that they stopped making them long ago, so it is special when you do see one out on the roads. If something breaks or...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Fingerprints of quantum entanglement

16.02.2018 | Information Technology

'Living bandages': NUST MISIS scientists develop biocompatible anti-burn nanofibers

16.02.2018 | Health and Medicine

Hubble sees Neptune's mysterious shrinking storm

16.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>