Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Exotic, gigantic molecules fit inside each other like Russian nesting dolls

23.01.2015

University of Chicago scientists have experimentally observed for the first time a phenomenon in ultracold, three-atom molecules predicted by Russian theoretical physicsist Vitaly Efimov in 1970.

In this quantum phenomenon, called geometric scaling, the triatomic molecules fit inside one another like an infinitely large set of Russian nesting dolls.


This illustration shows the sizes of triatomic molecules that follow the geometrical scaling predicted by Vitaly Efimov in 1970. University of Chicago physicists have reported evidence of this geometric scaling in three-atom, lithium-ceisum Efimov molecules at a temperature 200 nanokelvin, a fraction of a degree above absolute zero (minus 459.6 degrees Fahreneheit).

Credit: Cheng Chin group, University of Chicago

"This is a new rule in chemistry that molecular sizes can follow a geometric series, like 1, 2, 4, 8...," said Cheng Chin, professor in physics at UChicago. "In our case, we find three molecular states in this sequence where one molecular state is about 5 times larger than the previous one."

Chin and four members of his research group published their findings Dec. 9, 2014, in Physical Review Letters.

"Quantum theory makes the existence of these gigantic molecules inevitiable, provided proper--and quite challenging--conditions are created," said Efimov, now at the University of Washington.

The UChicago team observed three molecules in the series, consisting of one lithim atom and two cesium atoms in a vacuum chamber at the ultracold temperature of approximately 200 nanokelvin, a tiny fraction of a degree above absolute zero (minus 459.6 degrees Fahrenheit).

Infinitely large molecules

Given an infinitely large universe, the number of increasingly larger molecules in this cesium-lithium system also would extend to infinity. This remarkable idea stems from the exotic nature of quantum mechanics, which conforms confirms to different laws of physics than those that govern the universe on a macroscopic scale.

"These are certainly exotic molecules," said Shih-Kuang Tung, the postdoctoral scholar, now at Northwestern University, who led the project. Only under strict conditions could Tung and his colleagues see the geometric scaling in their Efimov molecules. It appears that neither two-atom nor four-atom molecules can achieve the Efimov state. "There's a special case for three atoms," Chin said.

Efimov's reaction to the research was twofold. "First, I am amazed by the predictive power of the quantum theory," he said. "Second, I am amazed by the skill of the experimentalists who managed to create those challenging conditions."

The finding is important because it shows that Efimov molecules, like other complex phenomena in nature, follow a simple mathematical rule. One other example in nature that displays geometric scaling are snowflakes, rooted in the microscopic physics of their hexagonal crystal structure.

A team at the University of Innsbruck in Austria, which included Chin, experimentally observed the first Efimov molecular state in 2006 in molecules consisting of three cesium atoms. In this Efimov state, three cesium atoms become entangled at temperatures slightly above absolute zero. They form a Borromean ring of three interlocking circles. Any two of them, however, will not interlock.

Chin switched his interest to lithium-cesium molecules in 2010 because observing geometrical scaling in the cesium system presented severe experimental difficulties.

Scaling factor

"The difficulty is that based on what we understand of Efimov's theory, the scaling factor is predicted to be 22.7 for the cesium system, which is a very large number," explained Chin, who also is a member of UChicago's James Franck and Enrico Fermi institutes. Scaling at such a large value demands an extremely low temperature, challenging to reach experimentally.

But the scaling factor of the lithium-cesium triatomic molecule was predicted to be more managable of 4.8. Indeed, after setting up their experiment, "We were able to see three of them at a more accessible temperature of 200 nano-Kelvin," Chin said. "Their sizes are measured to be 17, 86 and 415 nano-meters, respectively. They closely follow a geometric progression with the predicted scaling factor."

But even the lithium-cesium system presented a difficulty: the significantly differing masses of the two elements, which was critical for observing multiple Efimov states. Lithium is one of the lightest elements on the periodic table, while cesium is quite heavy. "One is really massive compared to the other," Tung said.

He compared working both elements into an ultracold experiment to dangling a monkey and an elephant from springs. They would hang at different levels, but they still needed to interact.

In the experiment, the UChicago physicists lowered the temperatures of the lithium and ceisum atoms separately, then brought them together to form the triatomic, Efimov molecules.

"It's a very complicated experiment," Tung said, one requiring an ultracold experimental tool called Feshbach resonance. Carried out in a magnetic field, Feshbach resonance allowed researchers to bind and control the interactions between the cesium and lithium atoms.

Cold atoms are subject to manipulation via Feshbach resonance, which allows the observation of geometric scaling. "Feshbach resonance is a really important tool for us," Tung said. He and his associates learned how to wield the tool effectively in the past three years.

"We needed to tune the Feshbach resonances very carefully in order to generate these Efimov molecules," Tung said.

The efforts culminated in experimental success. Efimov said the results made him feel like the parent of a successful child. "The parent is proud of the child's achievement, and he is also pround that in a sense he is part of the child's success."

Citation: "Geometric Scaling of Efimov States in a 6Li-133Cs Mixture," by Shih-Kuang Tung, Karina Jiménez-García, Jacob Johansen, Colin V. Parker, and Cheng Chin, Physical Review Letters, DOI: http://dx.doi.org/10.1103/PhysRevLett.113.240402

Funding: National Science Foundation and the Army Research Office.

Media Contact

Steve Koppes
skoppes@uchicago.edu
773-702-8366

 @UChicago

http://www-news.uchicago.edu 

Steve Koppes | EurekAlert!

Further reports about: Physical Review Letters cesium cesium atoms geometric physics temperature

More articles from Physics and Astronomy:

nachricht Hubble sees Neptune's mysterious shrinking storm
16.02.2018 | NASA/Goddard Space Flight Center

nachricht Supermassive black hole model predicts characteristic light signals at cusp of collision
15.02.2018 | Rochester Institute of Technology

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: 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 >>>