Scientists at MIT have figured out a key step toward the design of quantum information networks. The results are reported in the July 20th issue of Physical Review Letters and highlighted in APS's on-line journal Physics (physics.aps.org).
A quantum network – in which memory devices that store quantum states are interconnected with quantum information processing devices – is a prototype for designing a quantum internet. One path to making a quantum network is to map a light pulse onto nodes in a material system. Yet, it is one thing to catch a beam of light; it is more difficult to generate a signal that heralds that it has been successfully caught. Quantum systems follow Heisenberg's rule that observing an event may destroy it, so the system has to emit just the right kind of herald pulse so as not to erase the data.
Now, Haruka Tanji, Saikat Ghosh, Jonathan Simon, Benjamin Bloom, and Vladan Vuletic from MIT have demonstrated an atomic quantum memory that heralds the successful storage of a light beam in a cold atom gas. The atomic-ensemble memory can receive an arbitrary polarization state of an incoming photon, called a polarization qubit, announce successful storage of the qubit, and later regenerate another photon with the same polarization state. The herald signal only announces the fact the pulse has been captured, not details of the polarization, so the quantum information is preserved.
Turbulence is considered a nuisance because it slows down boats and jars airplanes. But for hundreds of years, physicists have been fascinated with the notoriously difficult problem of how to describe this phenomenon, which involves the formation and disappearance of vortices – swirling regions in a gas or liquid– over many different length and time scales.
Turbulence can also occur in quantum fluids, such as ultra-cold atom gases and superfluid helium. In a quantum fluid, the motion of the vortices is quantized; and, because quantum fluids have zero viscosity, the vortices cannot easily disappear.
These properties make quantum turbulence more stable and easier to understand than classical turbulence. Now, Emanuel Henn and colleagues at the University of Sao Paulo in Brazil and the University of Florence in Italy have created quantum turbulence in a gas of ultra-cold rubidium atoms by shaking it up with a magnetic field. In this way, they are able to control the formation of vortices and generate many different kinds of turbulence to explore a number of questions relevant to both its quantum and classical forms.
James Riordon | EurekAlert!
Ultra-compact phase modulators based on graphene plasmons
27.06.2017 | ICFO-The Institute of Photonic Sciences
Smooth propagation of spin waves using gold
26.06.2017 | Toyohashi University of Technology
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
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