Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

JILA measurements recast usual view of elusive force

09.02.2007
Physicists at JILA have demonstrated that the warmer a surface is, the stronger its subtle ability to attract nearby atoms, a finding that could affect the design of devices that rely on small-scale interactions, such as atom chips, nanomachines, and microelectromechanical systems (MEMS).

The research highlights an underappreciated aspect of the elusive Casimir-Polder force, one of the stranger effects of quantum mechanics. The force arises from the ever-present random fluctuation of microscopic electric fields in empty space. The fluctuations get stronger near a surface, and an isolated neutral atom nearby will feel them as a subtle pull—a flimsy, invisible rubber band between bulk objects and atoms that may be a source of friction, for example, in tiny devices.

The JILA group previously made the most precise measurement ever of Casimir-Polder, measuring forces hundreds of times weaker than ever before and at greater distances (more than 5 micrometers). JILA is a joint institute of the National Institute of Standards and Technology (NIST) and the University of Colorado at Boulder.

Now, as reported in a paper scheduled for this week's issue of Physical Review Letters, the JILA team has made the first measurement of the temperature dependence of this force. By using a combination of temperatures at opposite extremes—making a glass surface very hot while keeping the environment neutral and using ultracold atoms as a measurement tool—the new research underscores the power of surfaces to influence the Casimir-Polder force. That is, electric fields within the glass mostly reflect inside the surface but also leak out a little bit to greatly strengthen the fluctuations in neighboring space. As a result, says group leader and NIST Fellow Eric Cornell, "warm glass is stickier than cold glass."

The experiments demonstrate the practical use of a Bose-Einstein Condensate (BEC), a form of matter first created at JILA a decade ago. In a BEC, thousands of ultracold atoms coalesce into a "superatom" in a single quantum state. Cornell, who shared the 2001 Nobel Prize in Physics for this development, says the purity and sensitivity of a BEC makes it uniquely useful as a tool for measuring very slight forces and changes.

To measure the Casimir-Polder force, a BEC of about 250,000 rubidium atoms in a magnetic trap was placed a few micrometers from a glass plate. As the BEC was brought closer to the surface, the "wiggling" of the condensate was observed over time. Based on the changes in the oscillation frequency, the researchers calculated the force. In the latest experiment, measurements were made as a laser beam was used to heat the glass plate from room temperature (about 37 degrees C or 98 degrees F) to very hot (about 330 degrees C or 630 degrees F), while the surrounding environment was kept near room temperature. The strength of the force was shown to be nearly three times larger when the glass temperature doubled. The researchers also were able to separate the forces emanating from the surface versus the environment.

Laura Ost | EurekAlert!
Further information:
http://www.nist.gov

More articles from Physics and Astronomy:

nachricht Creation of coherent states in molecules by incoherent electrons
23.10.2017 | Tata Institute of Fundamental Research

nachricht Taming 'wild' electrons in graphene
23.10.2017 | Rutgers University

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: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

3rd Symposium on Driving Simulation

23.10.2017 | Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

 
Latest News

Taming 'wild' electrons in graphene

23.10.2017 | Physics and Astronomy

Mountain glaciers shrinking across the West

23.10.2017 | Earth Sciences

Scientists track ovarian cancers to site of origin: Fallopian tubes

23.10.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>