Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > A Microscopic View on Quantum Fluctuations: Scientists at the Max Planck Institute of Quantum Optics achieve direct imaging of quantum fluctuations at absolute zero temperature

Schematic view of the atom distribution in the optical lattice. Quantum fluctuations (white) are directly visible as neighbouring dark spots.
Credit: Max Planck Institute of Quantum Optics
Schematic view of the atom distribution in the optical lattice. Quantum fluctuations (white) are directly visible as neighbouring dark spots.

Credit: Max Planck Institute of Quantum Optics

Abstract:
Fluctuations are fundamental to many physical phenomena in our everyday life, such as the phase transitions from a liquid into a gas or from a solid into a liquid. But even at absolute zero temperature, where all motion in the classical world is frozen out, special quantum mechanical fluctuations prevail that can drive the transition between two quantum phases. Now a team around Immanuel Bloch and Stefan Kuhr at the Max Planck Institute of Quantum Optics (MPQ) has succeeded in directly observing such quantum fluctuations (Science, 14 October 2011, DOI: 10.1126/science.1209284). Using a high resolution microscope, they were able to image quantum-correlated particle-hole pairs in a gas of ultracold atoms. This allowed the physicists to unravel a hidden order in the crystal and to characterize the different phases of the quantum gas. The work was performed together with scientists from the Theory Division at the MPQ and ETH Zurich. These measurements open new ways to characterize novel quantum phases of matter.

A Microscopic View on Quantum Fluctuations: Scientists at the Max Planck Institute of Quantum Optics achieve direct imaging of quantum fluctuations at absolute zero temperature

Garching, Germany | Posted on October 17th, 2011

The scientists start by cooling a small cloud of rubidium atoms down to a temperature near absolute zero, about minus 273 degree Celsius. The ensemble is then subjected to a light field that severely restricts the motion of the particles along one-dimensional tubes of light aligned in parallel. An additional standing laser wave along the tubes creates a one-dimensional optical lattice that holds the atoms in a periodic array of bright and dark regions of light.

The atoms move in the periodic light field like electrons in solids. As these can be electric conductors or insulators, also the one-dimensional quantum gases can behave like a superfluid or like an insulator at low temperatures. In particular, the height of the optical lattice potential plays an important role: it determines whether the atom is fixed on a particular lattice site or whether it is able to move to a neighbouring site. At very large lattice depths, each lattice site is occupied by exactly one atom. This highly ordered state is called a "Mott insulator", after the British physicist and Nobel laureate Sir Neville Mott. When the lattice depth is decreased slightly, the atoms have enough energy to reach a neighbouring site by quantum mechanical tunneling. In this way, pairs of empty and doubly occupied sites emerge, so-called particle-hole pairs. Intriguingly, these quantum fluctuations also occur at absolute zero temperature, when all movement in the classical world is frozen out. The position of the quantum-correlated particle-hole pairs in the crystal is completely undetermined and is fixed only by the measurement process.

In recent experiments, the physicists around Stefan Kuhr and Immanuel Bloch had already developed a method, which allowed to image single atoms lattice site by lattice site. The atoms are cooled using laser beams, and the fluorescence photons emitted in this process are used to observe the atoms with a high resolution microscope. Holes naturally show up as dark spots, but so do doubly occupied sites as the two particles kick each other out of the lattice in the experiment. Therefore particle-hole pairs appear as two neighbouring dark lattice sites (see figure below). "With our technique, we can directly observe this fundamental quantum phenomenon for the first time", describes doctoral student Manuel Endres enthusiastically.

The physicists measure the number of neighbouring particle-hole pairs through a correlation function. With increasing kinetic energy, more and more particles tunnel to neighbouring sites and the pair correlations increase. However, when the number of particle-hole pairs is very large, it becomes difficult to unambiguously identify them. Hence the correlation function takes on smaller values. Finally, the ordered state of a Mott insulator vanishes completely und the quantum gas becomes a superfluid. Here fluctuations of holes and particles occur independently. The correlation function measured in the experiment is very well reproduced by model calculations, which were performed by scientists from the Theory Division at the MPQ and the ETH Zurich. Interestingly, the same investigations on two-dimensional quantum-gases clearly showed that quantum fluctuations are not as prominent as in one-dimensional systems.

The scientists extended their analysis to correlations between several lattice sites along a string. Such non-local correlation functions contain important information about the underlying many-body system and can be used as an order parameter to characterize different quantum phases. In the experiment described here, such non-local order parameters have been measured for the first time. In the future, the scientists plan to use these measurements for the detection of topological quantum phases. These can be useful for robust quantum computers and could help to understand superconductivity at high temperatures. Olivia Meyer-Streng

Original Publication:

M. Endres, M. Cheneau, T. Fukuhara, C. Weitenberg, P. Schauß, C. Groß, L. Mazza,

M.C. Banuls, L. Pollet, I. Bloch, and S. Kuhr

Observation of Correlated Particle-Hole Pairs and String Order in Low-Dimensional Mott Insulators

Science, 14 October 2011, DOI: 10.1126/science.1209284

####

For more information, please click here

Contacts:
Prof. Dr. Immanuel Bloch

Chair of Quantum Optics

LMU Munich, Schellingstr. 4

80799 München, Germany, and

Max Planck Institute of Quantum Optics

Hans-Kopfermann-Straße 1

85748 Garching b. München

Phone: +49 89 32905 138

e-mail:



Prof. Dr. Stefan Kuhr

University of Strathclyde

Department of Physics

107 Rottenrow East

Glasgow G4 0NG, U.K.

Phone: +44 141-548-3364

e-mail:



Manuel Endres

Max Planck Institute of Quantum Optics

Hans-Kopfermann-Straße 1

85748 Garching b. München

Phone: +49 89 32905 214

e-mail:



Dr. Olivia Meyer-Streng

Press & Public Relations

Max Planck Institute of Quantum Optics

Phone: +49 (0) 89 / 32905 - 213

e-mail:

Copyright © Max Planck Institute of Quantum Optics

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

Twisted graphene chills out: When two sheets of graphene are stacked in a special way, it is possible to cool down the graphene with a laser instead of heating it up, University of Manchester researchers have shown September 22nd, 2014

New star-shaped molecule breakthrough: Scientists at The University of Manchester have generated a new star-shaped molecule made up of interlocking rings, which is the most complex of its kind ever created September 22nd, 2014

Iranian Researchers Synthesize Stable Ceramic Nanopowders at Room Temperature September 20th, 2014

Arrowhead to Present at BioCentury's NewsMakers in the Biotech Industry Conference September 19th, 2014

Physics

Toward optical chips: A promising light source for optoelectronic chips can be tuned to different frequencies September 19th, 2014

Imaging

IEEE International Electron Devices Meeting To Celebrate 60th Anniversary as The Leading Technical Conference for Advanced Semiconductor Devices September 18th, 2014

FEI Opens New Technology Center in Czech Republic: FEI expands its presence in Brno with the opening of a new, larger facility September 18th, 2014

New NPZ100-403 Piezo Stage from nPoint Inc. September 17th, 2014

New non-invasive technique could revolutionize the imaging of metastatic cancer September 17th, 2014

Laboratories

Elusive Quantum Transformations Found Near Absolute Zero: Brookhaven Lab and Stony Brook University researchers measured the quantum fluctuations behind a novel magnetic material's ultra-cold ferromagnetic phase transition September 15th, 2014

'Squid skin' metamaterials project yields vivid color display: Rice lab creates RGB color display technology with aluminum nanorods September 15th, 2014

Berkeley Lab Licenses Boron Nitride Nanotube Technology: New material has unique mechanical and electronic properties September 13th, 2014

Advanced Light Source Sets Microscopy Record| Berkeley Lab Researchers Achieve Highest Resolution Ever with X-ray Microscopy September 11th, 2014

Discoveries

Twisted graphene chills out: When two sheets of graphene are stacked in a special way, it is possible to cool down the graphene with a laser instead of heating it up, University of Manchester researchers have shown September 22nd, 2014

New star-shaped molecule breakthrough: Scientists at The University of Manchester have generated a new star-shaped molecule made up of interlocking rings, which is the most complex of its kind ever created September 22nd, 2014

Iranian Scientists Separate Zinc Ion at Low Concentrations September 20th, 2014

Iranian Researchers Synthesize Stable Ceramic Nanopowders at Room Temperature September 20th, 2014

Announcements

Twisted graphene chills out: When two sheets of graphene are stacked in a special way, it is possible to cool down the graphene with a laser instead of heating it up, University of Manchester researchers have shown September 22nd, 2014

New star-shaped molecule breakthrough: Scientists at The University of Manchester have generated a new star-shaped molecule made up of interlocking rings, which is the most complex of its kind ever created September 22nd, 2014

Synthesis of Nanostructures with Controlled Shape, Size in Iran September 22nd, 2014

Iranian Scientists Separate Zinc Ion at Low Concentrations September 20th, 2014

Quantum nanoscience

Big Results Require Big Ambitions: Three young UCSB faculty receive CAREER awards from the National Science Foundation September 18th, 2014

Elusive Quantum Transformations Found Near Absolute Zero: Brookhaven Lab and Stony Brook University researchers measured the quantum fluctuations behind a novel magnetic material's ultra-cold ferromagnetic phase transition September 15th, 2014

Layered graphene sandwich for next generation electronics September 8th, 2014

Cool Calculations for Cold Atoms: New theory of universal three-body encounters September 2nd, 2014

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







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE