Featured Research

from universities, journals, and other organizations

Neutron experiments give unprecedented look at quantum oscillations

Date:
October 23, 2012
Source:
Oak Ridge National Laboratory
Summary:
Researchers have found that nitrogen atoms in the compound uranium nitride exhibit unexpected, distinct vibrations that form a nearly ideal realization of a physics textbook model known as the isotropic quantum harmonic oscillator.

A "nearly ideal realization" of a physics textbook model: Bands of scattered neutrons (colors at top) correspond to energy levels quantized in 50 meV lumps (bottom).
Credit: Image courtesy of Oak Ridge National Laboratory

Researchers at the Department of Energy's Oak Ridge National Laboratory have found that nitrogen atoms in the compound uranium nitride exhibit unexpected, distinct vibrations that form a nearly ideal realization of a physics textbook model known as the isotropic quantum harmonic oscillator.

In the experiment on the uranium nitride crystal -- with each of the light nitrogen atoms centered in a cage of heavier uranium atoms -- neutron scattering at ORNL's Spallation Neutron Source (SNS) revealed an unexpected series of distinct and evenly spaced oscillations: The nitrogen atom vibrates like a molecular-level ball on a spring.

"Students of physics are familiar with this idealized quantum 'mass on a spring,' but it is very unexpected to find such a precise literal version of this theoretical model in a real experiment," said Steve Nagler, director of ORNL's Quantum Condensed Matter Division of the Neutron Sciences Directorate and a co-author on the paper, published in the journal Nature Communications.

The researchers were using the intense neutron beams of the SNS to examine the magnetic properties of a single crystal of uranium nitride when they noticed the signatures of quantum oscillations. The researchers' technique -- neutron scattering -- is a tool commonly used to measure conventional quantized sound waves, or "phonon excitations" that occur at low frequencies. The measurements at SNS, however, probed higher frequencies well above the "phonon cutoff."

The new data, obtained using SNS's wide angular-range chopper spectrometer (ARCS) and fine-resolution Fermi chopper spectrometer (SEQUOIA) instruments, revealed up to 10 equally spaced energy levels corresponding to oscillations of individual nitrogen atoms in different quantum states. The team was "astonished" to find this series of high-energy vibrational modes in uranium nitride -- particularly in an experiment that originally set out to investigate magnetism in the material.

"We learn about the quantum harmonic oscillator in undergraduate physics courses, but you never believe you will find such a good example in nature," said Adam Aczel, a postdoctoral fellow within the Quantum Condensed Matter Division and lead author on the paper.

Uranium nitride is a material of interest in that it is being considered as a fuel for the next generation of more efficient nuclear power reactors. The phenomena observed at SNS could lend valuable insight into the material's performance and behavior as a nuclear fuel.

The SNS is the world's most powerful pulsed neutron source with a suite of unique, specialized instruments in its scientific user facility for the study of advanced materials. The uranium nitride research team combined data from ARCS and SEQUOIA with computational models to better understand their findings. The crystal of uranium nitride was provided by the Canadian Neutron Beam Centre (CNBC) of the National Research Council of Canada.

The team includes Aczel, Nagler, Garrett Granroth, Doug Abernathy, Greg MacDougall, G.D. Samolyuk and Malcolm Stocks of ORNL and W.J.L. Buyers of CNBC at Chalk River.

This research was supported as part of the Center for Defect Physics, an Energy Frontier Research Center funded by the DOE Office of Science.


Story Source:

The above story is based on materials provided by Oak Ridge National Laboratory. Note: Materials may be edited for content and length.


Journal Reference:

  1. A.A. Aczel, G.E. Granroth, G.J. MacDougall, W.J.L. Buyers, D.L. Abernathy, G.D. Samolyuk, G.M. Stocks, S.E. Nagler. Quantum oscillations of nitrogen atoms in uranium nitride. Nature Communications, 2012; 3: 1124 DOI: 10.1038/ncomms2117

Cite This Page:

Oak Ridge National Laboratory. "Neutron experiments give unprecedented look at quantum oscillations." ScienceDaily. ScienceDaily, 23 October 2012. <www.sciencedaily.com/releases/2012/10/121023112259.htm>.
Oak Ridge National Laboratory. (2012, October 23). Neutron experiments give unprecedented look at quantum oscillations. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2012/10/121023112259.htm
Oak Ridge National Laboratory. "Neutron experiments give unprecedented look at quantum oscillations." ScienceDaily. www.sciencedaily.com/releases/2012/10/121023112259.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