Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Solid stops light

08.01.2002


One laser can help halt another.
© SPL


A crystal that holds light could facilitate quantum computing.


Researchers in the United States and Korea have brought light to a complete standstill in a crystal. The pulse is effectively held within the solid, ready to be released at a later stage.


This trick could be used to store information in a quantum computer1.

Normal computers store information in simple binary form (1’s and 0’s) in electronic and magnetic devices. Stationary light pulses can encode information in more sophisticated ways that use the laws of quantum mechanics, making information processing more powerful.

Light moves at 186,000 miles per second through empty space, and was first stopped in its tracks at the beginning of last year. In that experiment, a vapour of metal atoms cooled close to absolute zero was shown to act like molasses on a passing light beam2,3.

Now Philip Hemmer, of the Air Force Research Laboratory at Hanscom Air Force Base in Massachusetts, and his colleagues have halted light in a crystal of yttrium silicate containing a few atoms of the element praseodymium.

Light-stopping solids would be much easier to incorporate into faster, more powerful computers than extremely cold gases. So the advance could aid information technology in much the same way that solid-state diodes and transistors made electronics more compact and robust than it could be with vacuum tubes.

Light slows down very slightly when it passes into any substance from a vacuum. The greater the refractive index of the material, the slower the light becomes. To make laser light travel very slowly, researchers create substances with immense refractive indices.

Hemmer’s team use a second laser beam to excite atoms in a substance to new energy states. Light can be considered to propagate through a material by being sequentially absorbed and re-emitted by atoms. The second beam manipulates this process so that it becomes more and more difficult for the light to make the step from one atom to the next.

The second beam couples the light pulse to the atoms. When shackled to these heavy objects, the pulse slows down. If this coupling is strong enough, the pulse comes to rest and all its energy is transferred to the atoms.

A light pulse that is brought to a standstill is not destroyed. The atoms ’remember’ it, so the pulse can be regenerated by changing the intensity of the coupling laser to allow the atoms to re-emit photons - the particles of which light is composed.


References

  1. Turukhin, A. V. et. al. Observation of ultraslow and stored light pulses in a solid. Physical Review Letters, 88, 023602, (2002).
  2. Liu, C., Dutton, Z., Behroozi, C. H. & Hau, L. V. Observation of coherent optical information storage in an atomic medium using halted light pulses. Physical Review Letters, 88, 023602, (2002).
  3. Phillips, D. F., Fleischhauer, A., Mair, A. & Walsworth, R. L. Storage of Light in Atomic Vapor. Nature, 409, 490 - 493, (2001).


PHILIP BALL | © Nature News Service
Further information:
http://www.nature.com/nsu/020107/020107-2.html

More articles from Information Technology:

nachricht Stable magnetic bit of three atoms
21.09.2017 | Sonderforschungsbereich 668

nachricht Drones can almost see in the dark
20.09.2017 | Universität Zürich

All articles from Information Technology >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

Im Focus: Fast, convenient & standardized: New lab innovation for automated tissue engineering & drug

MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems Holding GmbH about commercial use of a multi-well tissue plate for automated and reliable tissue engineering & drug testing.

MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Comet or asteroid? Hubble discovers that a unique object is a binary

21.09.2017 | Physics and Astronomy

Cnidarians remotely control bacteria

21.09.2017 | Life Sciences

Monitoring the heart's mitochondria to predict cardiac arrest?

21.09.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>