Featured Research

from universities, journals, and other organizations

Atoms with quantum-memory

Date:
February 28, 2013
Source:
Vienna University of Technology, TU Vienna
Summary:
Order tends towards disorder. This is also true for quantum states. Measurements show that in quantum mechanics this transition can be quite different from what we experience in our daily lives.

The Atom chip (above) - in the background the measured distributions are shown, which characterize the quantum physical state of the condensate.
Credit: Image courtesy of Vienna University of Technology, TU Vienna

Order tends towards disorder. This is also true for quantum states. Measurements at the Vienna University of Technology show that in quantum mechanics this transition can be quite different from what we experience in our daily lives.

Ice cubes in a cocktail glass melt until an equilibrium state is reached in which the ice cubes are gone. After that, the geometric shape of the ice cubes is completely lost. The liquid does not contain any memory of their shape, the ordered ice crystal has turned into disordered water molecules. Ultra cold Bose-Einstein condensates behave differently; these highly ordered clouds of ultra cold particles also approach a disordered equilibrium state, but they retain some "memory" about their initial state for a remarkably long time. This phenomenon does not depend on the temperature, it seems to be a stable, fundamental property of quantum physics.

Stopover on the Way to Chaos

In 2012, the research group around Professor Jörg Schmiedmayer at the Vienna Center for Quantum Science and Technology (VCQ), Vienna University of Technology, were able to show that they have found an intermediate state between order and disorder; the atoms of an ultra cold Bose-Einstein condensate tend towards an equilibrium state, in which their quantum physical properties are not visible any more.

This, however, does not happen continuously like the transition from an ice cube to liquid water. Instead, there is an intermediate step called "prethermalized state," in which the atoms remain for a surprisingly long time without forgetting about their quantum mechanical origin. "If we split the atom cloud into two parts and recombine them after some time, a wave pattern forms," Jörg Schmiedmayer explains. "That is proof that the atom clouds still contain information about having emerged from a highly ordered quantum physical state."

Intermediate State Independent of Temperature

Now the scientists have managed to take a closer look at this transition -- and it turns out to be remarkably stable with respect to external conditions. From experience, we are used to the opposite case: "Imagine a room full of air, and a vacuum in the room next to it," says Max Kuhnert (Vienna University of Technology). "When we open a door between those rooms, the system approaches an equilibrium, until the molecules are evenly distributed in the two rooms. This transition, however, strongly depends on external parameters such as pressure and temperature." The higher the pressure and the temperature, the faster information about the initial state is lost -- be it information about the initial distribution of air molecules or about the geometry of melting ice cubes.

"The prethermalized state of our atom clouds is reached quite independently from pressure and temperature," says Max Kuhnert. The experiments, which have now been published in Physical Review Letters, show that this state is characterized by a new length scale. This so-called correlation length is a direct measure of the quantum memory of the ordered initial state. It is the length scale on which the quantum physical properties of the atom clouds can still be perceived.

"This emergent correlation length is defined by the density of the initial quantum gas, but it only becomes visible in the dynamics of the transition from an ordered state into the prethermalized state" says Jörg Schmiedmayer. "The fact that this correlation length does not depend on the initial temperature at all strongly indicates that the prethermalized state is a fundamental property of quantum physics and has major significance," Max Kuhnert believes. A deeper understanding of this quantum state is expected not only to explain ultra cold Bose-Einstein condensates, it may also shed some light on the processes in the early universe, or it could help to understand phenomena in the quark-gluon-plasma created in high energy particle accelerators.


Story Source:

The above story is based on materials provided by Vienna University of Technology, TU Vienna. Note: Materials may be edited for content and length.


Journal Reference:

  1. Maximilian Kuhnert, Remi Geiger, Tim Langen, Michael Gring, Bernhard Rauer, Takuya Kitagawa, Eugene Demler, David Adu Smith, Jörg Schmiedmayer. Multimode dynamics and emergence of a characteristic length-scale in a one-dimensional quantum system. Submitted to Arxiv, 2013 [link]

Cite This Page:

Vienna University of Technology, TU Vienna. "Atoms with quantum-memory." ScienceDaily. ScienceDaily, 28 February 2013. <www.sciencedaily.com/releases/2013/02/130228080242.htm>.
Vienna University of Technology, TU Vienna. (2013, February 28). Atoms with quantum-memory. ScienceDaily. Retrieved August 20, 2014 from www.sciencedaily.com/releases/2013/02/130228080242.htm
Vienna University of Technology, TU Vienna. "Atoms with quantum-memory." ScienceDaily. www.sciencedaily.com/releases/2013/02/130228080242.htm (accessed August 20, 2014).

Share This




More Matter & Energy News

Wednesday, August 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Awesome New Camouflage Sheet Was Inspired By Octopus Skin

Awesome New Camouflage Sheet Was Inspired By Octopus Skin

Newsy (Aug. 19, 2014) — Scientists have developed a new device that mimics the way octopuses blend in with their surroundings to hide from dangerous predators. Video provided by Newsy
Powered by NewsLook.com
Researcher Testing on-Field Concussion Scanners

Researcher Testing on-Field Concussion Scanners

AP (Aug. 19, 2014) — Four Texas high school football programs are trying out an experimental system designed to diagnose concussions on the field. The technology is in response to growing concern over head trauma in America's most watched sport. (Aug. 19) Video provided by AP
Powered by NewsLook.com
Green Power Blooms as Japan Unveils 'hydrangea Solar Cell'

Green Power Blooms as Japan Unveils 'hydrangea Solar Cell'

AFP (Aug. 19, 2014) — A solar cell that resembles a flower is offering a new take on green energy in Japan, where one scientist is searching for renewables that look good. Duration: 01:29 Video provided by AFP
Powered by NewsLook.com
Tiny Satellites, Like The One Tossed From ISS, On The Rise

Tiny Satellites, Like The One Tossed From ISS, On The Rise

Newsy (Aug. 18, 2014) — The Chasqui I, hand-delivered into orbit by a Russian cosmonaut, is one of hundreds of small satellites set to go up in the next few years. Video provided by Newsy
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