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

Nanotech could rid cattle of ticks, with less collateral damage September 1st, 2015

Scientists 'squeeze' light one particle at a time: A team of scientists have measured a bizarre effect in quantum physics, in which individual particles of light are said to have been 'squeezed' -- an achievement which at least one textbook had written off as hopeless September 1st, 2015

Using ultrathin sheets to discover new class of wrapped shapes: UMass Amherst materials researchers describe a new regime of wrapped shapes August 31st, 2015

Physics

Scientists 'squeeze' light one particle at a time: A team of scientists have measured a bizarre effect in quantum physics, in which individual particles of light are said to have been 'squeezed' -- an achievement which at least one textbook had written off as hopeless September 1st, 2015

Using ultrathin sheets to discover new class of wrapped shapes: UMass Amherst materials researchers describe a new regime of wrapped shapes August 31st, 2015

Govt.-Legislation/Regulation/Funding/Policy

An engineered surface unsticks sticky water droplets August 31st, 2015

New material science research may advance tech tools August 31st, 2015

Artificial leaf harnesses sunlight for efficient fuel production August 30th, 2015

Researchers use DNA 'clews' to shuttle CRISPR-Cas9 gene-editing tool into cells August 30th, 2015

Possible Futures

Sediment dwelling creatures at risk from nanoparticles in common household products August 13th, 2015

Harris & Harris Group Reports Financial Statements as of June 30, 2015, and Announces a Stock Repurchase Program August 10th, 2015

Molecular trick alters rules of attraction for non-magnetic metals August 5th, 2015

Global Carbon Nanotubes Industry 2015: Acute Market Reports August 4th, 2015

Announcements

Nanotech could rid cattle of ticks, with less collateral damage September 1st, 2015

Scientists 'squeeze' light one particle at a time: A team of scientists have measured a bizarre effect in quantum physics, in which individual particles of light are said to have been 'squeezed' -- an achievement which at least one textbook had written off as hopeless September 1st, 2015

An engineered surface unsticks sticky water droplets August 31st, 2015

New material science research may advance tech tools August 31st, 2015

Alliances/Trade associations/Partnerships/Distributorships

National Space Society Welcomes Janet Ivey As New NSS Governor: Janet Ivey of Janet's Planet is NOW IN ORBIT as a member of the Board of Governors of the National Space Society August 27th, 2015

National Space Society Welcomes Geoff Notkin As New NSS Governor August 26th, 2015

XEI Scientific appoints EM Resolutions as Distributor for the UK & Irish markets August 11th, 2015

Omni Nano and Time Warner Cable Partner to Provide Nanotechnology Education to the Boys & Girls Clubs of Los Angeles: A $10,000 Donation to Benefit Youth of Los Angeles County's Boys & Girls Clubs August 4th, 2015

Quantum nanoscience

Scientists 'squeeze' light one particle at a time: A team of scientists have measured a bizarre effect in quantum physics, in which individual particles of light are said to have been 'squeezed' -- an achievement which at least one textbook had written off as hopeless September 1st, 2015

Seeing quantum motion August 30th, 2015

Quantum diffraction at a breath of nothing: Physicists build stable diffraction structure in atomically thin graphene August 25th, 2015

Southampton scientists find new way to detect ortho-para conversion in water August 25th, 2015

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