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!
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On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
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Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
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Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
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Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
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