Featured Research

from universities, journals, and other organizations

Flatland Physics Probes Mysteries Of Superfluidity

Date:
April 2, 2009
Source:
National Institute of Standards and Technology (NIST)
Summary:
New experimental results on the behavior of ultracold, two-dimensional gases reported by physicists may help clarify the mysterious phenomenon called "superfluidity" -- frictionless flow.

A gas of atoms arranged in a single, flat layer ordinarily has "thermal" behavior (left) in which the atoms act as individual entities. At lowered temperatures, the gas transforms into a "quasi-condensate" (middle) consisting of little islands (schematically represented as colored blobs) that fluctuate in time; within each island atoms act as a single coordinated entity. At lower temperatures still, the gas enters the superfluid "BKT" phase (right): the islands start to coalesce and atoms can flow frictionlessly within the merged area.
Credit: Kristian Helmerson, JQI

If physicists lived in Flatland—the fictional two-dimensional world invented by Edwin Abbott in his 1884 novel—some of their quantum physics experiments would turn out differently (not just thinner) than those in our world. The distinction has taken another step from speculative fiction to real-world puzzle with a paper from the Joint Quantum Institute (JQI) reporting on a Flatland arrangement of ultracold gas atoms.

The new results, which don’t quite jibe with earlier Flatland experiments in Paris, might help clarify a strange property: “superfluidity.”

In three dimensions, cooling a gas of certain atoms to sufficiently low temperatures turns them into a Bose-Einstein condensate (BEC). As predicted in the 1920s (and first demonstrated in 1995) the once individualistic gas atoms begin to move as a single, coordinated entity. But back in 1970, theorists predicted that something different would happen in two dimensions: an ultracold gas of interacting atoms would undergo the analogous “Berezinskii, Kosterlitz and Thouless” (BKT) transition, in which atoms don’t quite move in lockstep as they do in a BEC, but mysteriously share some of a BEC’s properties, such as superfluidity, or frictionless flow.

In new experiments at the Joint Quantum Institute (JQI), a partnership of the National Institute of Standards and Technology (NIST) and the University of Maryland, a team of physicists led by JQI Fellow Kristian Helmerson has achieved the latest experimental observation of the BKT transition. The JQI researchers trap and cool a micron-thick layer of sodium atoms, confined to move in only two dimensions. At higher temperatures, the atoms have normal “thermal” behavior in which they act as individual entities, but then as the temperature lowers, the gas transforms into a “quasi-condensate,” consisting of little islands each behaving like a tiny BEC.

By further lowering the temperature, the gas makes the transition to a BKT superfluid where the islands begin to merge into a sort of “United States” of superfluidity. In this situation, an atom can flow unimpeded between neighboring “states” since the borders of the former islands are not well defined, but one can tell that the atom is “not in Kansas anymore,” in contrast to a BEC where one cannot pinpoint the location of a particular atom anywhere in the gas.

When a Paris group lowered the temperature of their 2-D gas in earlier experiments, they only saw a sharp transition from thermal behavior to a BKT superfluid, rather than the additional step of the non-superfluid quasi-condensate. But the Paris group used rubidium atoms, which are heavier and more strongly interacting, possibly exhibiting a qualitatively different behavior. These new results may cast light on superfluidity, which decades after its discovery still seems to hold new mysteries.


Story Source:

The above story is based on materials provided by National Institute of Standards and Technology (NIST). Note: Materials may be edited for content and length.


Journal Reference:

  1. P. Cladι, C. Ryu, A. Ramanathan, K. Helmerson and W.D. Phillips. Observation of a 2D Bose-gas: From thermal to quasi-condensate to superfluid. Physical Review Letters, 2009; (forthcoming)

Cite This Page:

National Institute of Standards and Technology (NIST). "Flatland Physics Probes Mysteries Of Superfluidity." ScienceDaily. ScienceDaily, 2 April 2009. <www.sciencedaily.com/releases/2009/03/090325132340.htm>.
National Institute of Standards and Technology (NIST). (2009, April 2). Flatland Physics Probes Mysteries Of Superfluidity. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2009/03/090325132340.htm
National Institute of Standards and Technology (NIST). "Flatland Physics Probes Mysteries Of Superfluidity." ScienceDaily. www.sciencedaily.com/releases/2009/03/090325132340.htm (accessed July 31, 2014).

Share This




More Matter & Energy News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Britain Testing Driverless Cars on Roadways

Britain Testing Driverless Cars on Roadways

AP (July 30, 2014) — British officials said on Wednesday that driverless cars will be tested on roads in as many as three cities in a trial program set to begin in January. Officials said the tests will last up to three years. (July 30) Video provided by AP
Powered by NewsLook.com
7 Ways to Use Toothpaste: Howdini Hacks

7 Ways to Use Toothpaste: Howdini Hacks

Howdini (July 30, 2014) — Fresh breath and clean teeth are great, but have you ever thought, "my toothpaste could be doing more". Well, it can! Lots of things! Howdini has 7 new uses for this household staple. Video provided by Howdini
Powered by NewsLook.com
Amid Drought, UCLA Sees Only Water

Amid Drought, UCLA Sees Only Water

AP (July 30, 2014) — A ruptured 93-year-old water main left the UCLA campus awash in 8 million gallons of water in the middle of California's worst drought in decades. (July 30) Video provided by AP
Powered by NewsLook.com
Smartphone Powered Paper Plane Debuts at Airshow

Smartphone Powered Paper Plane Debuts at Airshow

AP (July 30, 2014) — Smartphone powered paper airplane that was popular on crowdfunding website KickStarter makes its debut at Wisconsin airshow (July 30) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



    Save/Print:
    Share:  

    Free Subscriptions


    Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

    Get Social & Mobile


    Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

    Have Feedback?


    Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
    Mobile iPhone Android Web
    Follow Facebook Twitter Google+
    Subscribe RSS Feeds Email Newsletters
    Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins