Featured Research

from universities, journals, and other organizations

To be or not to be a pair: Giant molecules in a quantum superposition

Date:
November 29, 2010
Source:
University of Stuttgart
Summary:
In human relationships, the question of being a couple or not has a yes-or-no answer: either one is a couple or not. Quantum physics offers an interesting alternative. There, the couples are pairs of atoms that are held together by binding forces to form molecules. Quantum mechanics allows another loophole: a superpostion of free and bound state, where the two atoms are bound and free at the same time. Although this is impossible in our classical world, it is a well known property for quantum mechanical states. Such superpositions have now been observed for weakly bound ultralong-range molecules.

Interferometer for Rydberg-molecules: A laser pulse (grau) excites pairs of Rubidium Atoms into a superposition state between free atoms and bound molecules. With a second pulse, the different temporal evolution of these two states can be mapped back to the number of detected molecules.
Credit: Image courtesy of University of Stuttgart

In human relationships, the question of being a couple or not has a yes-or-no answer: either one is a couple or not. Quantum physics offers an interesting alternative. There, the couples are pairs of atoms that are held together by binding forces to form molecules. Quantum mechanics allows another loophole: a superpostion of free and bound state, where the two atoms are bound and free at the same time. Although this is impossible in our classical world, it is a well known property for quantum mechanical states. Such superpositions have now been observed at the University of Stuttgart for weakly bound ultralong-range molecules.

Physicist Tilman Pfau and his group showed, that these superposition states last for several millionth of a second -- too short for a real relationship, but long enough for molecules, as Björn Butscher and his colleagues report in the online version of Nature Phyiscs.

Only recently, the Stuttgart physicists provided experimental proof for the existence of the so-called ultralong-range Rydberg molecules. These are weakly bound molecules where one atom is in its ground-state while the other atom is in a highly excited state -- a Rydberg state. With bond lengths of 100 nanometers, these molecules are extraordinarilly large. In their new experiment, the scientists now demonstrate the control of these superposition states.

To form the exotic molecule, two ground state atoms need to be at the right distance. Since atoms at room temperature are moving too fast to form a molecule, the physicists cool a gas of Rubidium atoms to a temperature close to the absolute zero temperature and illuminate it with laser pulses. This lifts the outer electron of one atom to a high orbit and Rydberg-molecules can be formed. In their new experiment the physicists could show that they can coherently control the transition from the unbound state of two free atoms to the molecular state. This means that the atom-pair is bound to the light so much that it oscillates periodically between the bound and the unbound state and take all intermediate superpositions while the light is on.

Depending on the length of the laser pulse, they can create a bound pair or an unbound pair or a pair that is simultaneously in both, the bound and in the unbound state -- the superposition state. If the pair is in such a superposition, it is extremely sensitive to external effects that diffently affect the bound and the unbound state. Using two separated laser pulses, the physicists could realize an interferometer for bound states that they employed to measure the lifetime of the molecules.

This work has been funded by the Deutschen Forschungsgemeinschaft DFG, SFB/TRR 21 (Control of quantum correlations in tailored matter) and the Carl-Zeiss-Stiftung unterstützt.


Story Source:

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


Journal Reference:

  1. B. Butscher, J. Nipper, J. B. Balewski, L. Kukota, V. Bendkowsky, R. Löw, T. Pfau. Atom–molecule coherence for ultralong-range Rydberg dimers. Nature Physics, 2010; DOI: 10.1038/nphys1828

Cite This Page:

University of Stuttgart. "To be or not to be a pair: Giant molecules in a quantum superposition." ScienceDaily. ScienceDaily, 29 November 2010. <www.sciencedaily.com/releases/2010/11/101124085945.htm>.
University of Stuttgart. (2010, November 29). To be or not to be a pair: Giant molecules in a quantum superposition. ScienceDaily. Retrieved April 20, 2014 from www.sciencedaily.com/releases/2010/11/101124085945.htm
University of Stuttgart. "To be or not to be a pair: Giant molecules in a quantum superposition." ScienceDaily. www.sciencedaily.com/releases/2010/11/101124085945.htm (accessed April 20, 2014).

Share This



More Matter & Energy News

Sunday, April 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Small Reactors Could Be Future of Nuclear Energy

Small Reactors Could Be Future of Nuclear Energy

AP (Apr. 17, 2014) — After the Fukushima nuclear disaster, the industry fell under intense scrutiny. Now, small underground nuclear power plants are being considered as the possible future of the nuclear energy. (April 17) Video provided by AP
Powered by NewsLook.com
Horseless Carriage Introduced at NY Auto Show

Horseless Carriage Introduced at NY Auto Show

AP (Apr. 17, 2014) — An electric car that proponents hope will replace horse-drawn carriages in New York City has also been revealed at the auto show. (Apr. 17) Video provided by AP
Powered by NewsLook.com
Honda's New ASIMO Robot, More Human-Like Than Ever

Honda's New ASIMO Robot, More Human-Like Than Ever

AFP (Apr. 17, 2014) — It walks and runs, even up and down stairs. It can open a bottle and serve a drink, and politely tries to shake hands with a stranger. Meet the latest ASIMO, Honda's humanoid robot. Duration: 00:54 Video provided by AFP
Powered by NewsLook.com
German Researchers Crack Samsung's Fingerprint Scanner

German Researchers Crack Samsung's Fingerprint Scanner

Newsy (Apr. 16, 2014) — German researchers have used a fake fingerprint made from glue to bypass the fingerprint security system on Samsung's new Galaxy S5 smartphone. 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