Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Synthetic magnetism achieved by optical methods

This is the first figure to accompany the Joint Quantum Institute press release about synthetic magnetism.

Credit: JQI
This is the first figure to accompany the Joint Quantum Institute press release about synthetic magnetism. Credit: JQI

Abstract:
Technique enables unprecedented insights

Synthetic magnetism achieved by optical methods

College Park, MD | Posted on December 4th, 2009

For the first time, physicists have used laser light to create "synthetic magnetism," an exotic condition in which neutral atoms suddenly begin to behave as if they were charged particles interacting with a magnetic field -- even though no such field is present and the atoms have no charge. The achievement provides unprecedented insights into fundamental physics and the behavior of quantum objects, and opens up entirely new ways to study the nature of condensed-matter systems that were barely imaginable before.

There are many phenomena of urgent interest to physicists, such as the action of electrons restrained in two dimensions in a magnetic field, that are difficult to investigate in conventional materials such as semiconductors. Not only is it hard to control the numerous variables involved, but there are always defects and irregularities in the experimental samples. Nonetheless, such research is important both to basic quantum mechanics and to applied fields such as quantum computing and information science. Synthetic magnetism provides a way to model and examine such quantum systems while exercising precision control over the parameters.

"The creation of synthetic magnetic fields for ultracold neutral atoms enables previously impossible experiments in these most quintessential of quantum mechanical systems," says research group leader Ian Spielman, a Fellow of the Joint Quantum Institute and physicist at the National Institute of Standards and Technology (NIST). Spielman and colleagues describe the work in a paper published in the Dec. 3 issue of Nature.

The team began by taking a population of rubidium-87 atoms, decelerating them with a Zeeman slower and then confining them in a magneto-optical trap. The atoms then underwent evaporative cooling in a magnetic trap and then an optical-dipole trap until approximately 250,000 remained at a temperature of about 100 nano Kelvin. Under those ultracold, low-energy conditions, the atoms formed a Bose-Einstein condensate (BEC) V a strange state of matter in which most of the atoms in a group occupy the same minimum-energy quantum state, somewhat as if they collectively constituted a single "super atom."

A small, spatially varying, magnetic bias field was applied across the BEC, producing a gradient that affected the atoms differently depending on their position along one axis of the trap. [See Figure 1.] Then two near-infrared (wavelength, =801.7 nm) laser beams, oriented at 90 degree angles to each other, were aimed into the atoms. The scientists adjusted the beams to have very slightly different frequencies. The cumulative effect of the gradient field and the two laser beams altered the properties of the atoms (in particular, their momentum along one axis) in a way that depended on their location in the trap and their interaction with the beams.

Those differences, the researchers found, could be tuned by making slight changes in the frequencies of the laser beams, in effect conferring a "charge" on sub-populations of the neutral atoms and creating a synthetic magnetic field to which they reacted.

By varying the beams and the gradient, and thus controlling the position-dependent momentum potentials of the atoms, the team observed that V as predicted in a theory paper Spielman had authored earlier this year V atoms at specific points in the trap began to move in a way mathematically equivalent to the way a charged particle would revolve in a magnetic field. The effect caused small quantized vortices of atoms to enter the BEC.

To confirm and measure the magnitude of the phenomenon, the team took pictures of the BEC approximately 25 milliseconds after shutting off all fields and beams in the trap. Images of the expanding atomic cloud clearly showed that when the synthetic magnetism was not present, the atoms in the BEC had the customary distribution. But when the synthetic field was activated, vortices were plainly visible V a clear indication that an optically induced synthetic magnetic field had been created for the first time.

The results are expected to have a substantial impact on various fields of inquiry in quantum science, especially the behavior of electrons confined in different geometries, as they are in real materials. In particular, it will allow researchers to explore how the energy spectrum of electrons in a crystal lattice varies with the magnetic field applied to the system. (This subject produced the now-famous theoretical plot of energy levels called "Hofstadter's butterfly" because of its elegant, wing-like curves.)

In addition, synthetic magnetism should prove valuable in characterizing aspects of the quantum Hall effect, a phenomenon observed in two-dimensional systems of electrons in a magnetic field. In that situation, the electrons naturally tend to follow circular ("cyclotron") orbits; and the energy levels of those orbits are quantized. The National Institute of Standards and Technology uses the quantum Hall effect to define the international standard of resistance.

Further improvements on the synthetic magnetism work, Spielman says, should allow new ways to investigate these and other phenomena.

"By adding an optical lattice potential to our synthetic magnetic field," he says, "we have the opportunity to create both long anticipated systems such as the Hofstadter butterfly -- an iconic pattern of energy levels for non-interacting particles -- and potentially to realize totally new states of matter such as quantum Hall states of bosons."

The research was partially supported by the Office of Naval Research, the Office of the Director of National Intelligence, the Army Research Office and the National Science Foundation through the NSF Physics Frontier Center at the Joint Quantum Institute.


####

About Joint Quantum Institute, University of Maryland
The Joint Quantum Institute (JQI) is a research partnership between University of Maryland (UMD) and the National Institute of Standards and Technology, with the support and participation of the Laboratory for Physical Sciences.

Created in 2006 to pursue theoretical and experimental studies of quantum physics in the context of information science and technology, JQI is located on UMD's College Park campus. For further information, see jqi.umd.edu.

For more information, please click here

Contacts:
Dr. Ian Spielman

301-975-8664
University of Maryland

Copyright © Eurekalert

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Graphene is strong, but is it tough? Berkeley Lab scientists find that polycrystalline graphene is not very resistant to fracture February 7th, 2016

Lithium battery catalyst found to harm key soil microorganism February 7th, 2016

Scientists take key step toward custom-made nanoscale chemical factories: Berkeley Lab researchers part of team that creates new function in tiny protein shell structures February 6th, 2016

Discovery of the specific properties of graphite-based carbon materials February 6th, 2016

Physics

Polar vortices observed in ferroelectric: New state of matter holds promise for ultracompact data storage and processing February 4th, 2016

The quantum fridge: It all comes down to quantum physics: scientists at TU Wien have analyzed why some gases can be cooled down to extremely low temperatures February 2nd, 2016

Unconventional superconductivity near absolute zero temperature: Quantum critical point could be the reason for high temperature superconductivity February 2nd, 2016

Electrons and liquid helium advance understanding of zero-resistance: Study of electrons on liquid helium systems sheds light on zero-resistance phenomenon in semiconductors February 2nd, 2016

Govt.-Legislation/Regulation/Funding/Policy

Lithium battery catalyst found to harm key soil microorganism February 7th, 2016

Scientists take key step toward custom-made nanoscale chemical factories: Berkeley Lab researchers part of team that creates new function in tiny protein shell structures February 6th, 2016

Hepatitis virus-like particles as potential cancer treatment February 5th, 2016

Researchers discover new phase of boron nitride and a new way to create pure c-BN February 5th, 2016

Possible Futures

Graphene is strong, but is it tough? Berkeley Lab scientists find that polycrystalline graphene is not very resistant to fracture February 7th, 2016

Scientists take key step toward custom-made nanoscale chemical factories: Berkeley Lab researchers part of team that creates new function in tiny protein shell structures February 6th, 2016

Discovery of the specific properties of graphite-based carbon materials February 6th, 2016

Hepatitis virus-like particles as potential cancer treatment February 5th, 2016

Announcements

Graphene is strong, but is it tough? Berkeley Lab scientists find that polycrystalline graphene is not very resistant to fracture February 7th, 2016

Lithium battery catalyst found to harm key soil microorganism February 7th, 2016

Scientists take key step toward custom-made nanoscale chemical factories: Berkeley Lab researchers part of team that creates new function in tiny protein shell structures February 6th, 2016

Discovery of the specific properties of graphite-based carbon materials February 6th, 2016

Alliances/Trade associations/Partnerships/Distributorships

Vesper Collaborates with GLOBALFOUNDRIES to Deliver First Piezoelectric MEMS Microphones: Acoustic sensing company works with top foundry to support mass-market consumer products January 21st, 2016

Imec and Cloudtag Collaborate on High Quality Frictionless Wearables for Lifestyle Coaching: Next-generation health and fitness tracker Cloudtag TrackTM launched at CES 2016 January 7th, 2016

Technical partnership at the top Oxford Instruments and Zurich Instruments announce a technical collaboration for low temperature physics January 7th, 2016

Production of Graphene Oxide Nanosheets to Economize Fuel Cells January 1st, 2016

Quantum nanoscience

Spin dynamics in an atomically thin semi-conductor February 1st, 2016

New record in nanoelectronics at ultralow temperatures January 28th, 2016

Leti to Host Workshop on New Photonics Applications During SPIE Photonics West: Researchers also Will Present Four Invited Papers At Feb. 13-18 Conference, 14 Papers, Overall January 25th, 2016

Mechanical quanta see the light January 20th, 2016

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







Car Brands
Buy website traffic