from the band-name-of-the-week dept.
For the first time in the history of quantum mechanics, scientists have been able to transmit a black and white image without having to send any physical particles. The phenomenon can be explained using the Zeno effect, the same effect that explains that movement itself is impossible.
The journal article is in Proceedings of the National Academy of Sciences of the United States of America (DOI: 10.1073/pnas.1614560114)
Wikipedia has an article about the quantum Zeno effect.
Physicists Break Distance Record for Quantum Teleportation
First Covert Communication System with Lasers
Long-Range Secure Quantum Communication System Developed
China's "Quantum-Enabled Satellite" Launches
How to Outwit Noise in Quantum Communication
Scientists develop first completely covert communication system with lasers:
As computing power continues to increase, previously unbreakable forms of encryption have crumbled. Now, though, we appear to be on the verge of what may be truly unbreakable quantum encryption. It's possible in the not too distant future no one will be able to spy on a message secured with these advanced methods no matter how long they hammer at it. Researchers are now looking to take things one step further and completely camouflage a message so no one even knows that a message was sent in the first place. If you can't even risk an eavesdropper knowing that a message has been sent, let alone what it says, you need a covert communication system. That's the idea at the heart of a new experiment conducted at the University of Massachusetts. Researchers there have developed a method of using photons to make a message invisible to everyone but the intended recipient.
The covert system relies on a technique called pulse position modulation, which is actually much more simple than you'd expect. It involves dividing a second, minute, or other unit of time into discrete bands, each of which correspond to a different letter or symbol. This code would have to be shared with the intended recipient ahead of time, which is perhaps the most notable flaw with the whole scheme. Once that's done, through, a series of pulses could be delivered like optical Morse code to convey a message.
http://www.extremetech.com/extreme/182142-scientis ts-develop-first-completely-covert-communication-s ystem-with-lasers
Researchers at the National Institute of Standards and Technology (NIST) have "teleported" or transferred quantum information carried in light particles over 100 kilometers (km) of optical fiber, four times farther than the previous record.
The experiment confirmed that quantum communication is feasible over long distances in fiber. Other research groups have teleported quantum information over longer distances in free space, but the ability to do so over conventional fiber-optic lines offers more flexibility for network design.
"Only about 1 percent of photons make it all the way through 100 km of fiber," NIST's Marty Stevens says. "We never could have done this experiment without these new detectors, which can measure this incredibly weak signal."
Until now, so much quantum data was lost in fiber that transmission rates and distances were low. The new NTT/NIST teleportation technique could be used to make devices called quantum repeaters that could resend data periodically in order to extend network reach, perhaps enough to eventually build a "quantum internet." Previously, researchers thought quantum repeaters might need to rely on atoms or other matter, instead of light, a difficult engineering challenge that would also slow down transmission.
A group of scientists from ITMO University in Saint Petersburg, Russia has developed a novel approach to the construction of quantum communication systems for secure data exchange. The experimental device based on the results of the research is capable of transmitting single-photon quantum signals across distances of 250 kilometers or more, which is on par with other cutting edge analogues. The research paper was published in the Optics Express journal.
Information security is becoming more and more of a critical issue not only for large companies, banks and defense enterprises, but even for small businesses and individual users. However, the data encryption algorithms we currently use for protecting our data are imperfect -- in the long-term, their logic can be cracked. Regardless of how complex and intricate the algorithm is, getting round it is just the matter of time.
Contrary to algorithm-based encryption, systems that protect information by making use of the fundamental laws of quantum physics, can make data transmission completely immune to hacker attacks in the future. Information in a quantum channel is carried by single photons that change irreversibly once an eavesdropper attempts to intercept them. Therefore, the legitimate users will instantly know about any kind of intervention.
[...] In order to encode quantum bits in the system, laser radiation is directed into a special device called the electro-optical phase modulator. Inside the modulator the central carrier wave emitted by the laser is split into several independent waves. After the signal is transmitted through the cable, the same splitting occurs on the receiver end. Depending on the relative phase shift of the waves generated by the sender and the receiver, the waves will either enhance or cancel each other. This pattern generated by overlapping wave phases is then converted into the combination of binary digits, 1 and 0, which serves to compile a quantum key.
China has launched a satellite that will beam entangled photons to base stations on Earth:
China has successfully launched the world's first quantum-enabled satellite, state media said. It was carried on a rocket which blasted off from the Jiuquan Satellite Launch Centre in China's north west early on Tuesday. The satellite is named after the ancient Chinese scientist and philosopher Micius. The project tests a technology that could one day offer digital communication that is "hack-proof". But even if it succeeds, it is a long way off that goal, and there is some mind-bending physics to get past first.
The satellite will create pairs of so-called entangled photons - tiny sub-atomic particles of light whose properties are dependent on each other - beaming one half of each pair down to base stations in China and Austria. This special kind of laser has several curious properties, one of which is known as "the observer effect" - its quantum state cannot be observed without changing it. So, if the satellite were to encode an encryption key in that quantum state, any interception would be obvious. It would also change the key, making it useless.
How to reliably transfer quantum information when the connecting channels are impacted by detrimental noise? Scientists at the University of Innsbruck and TU Wien (Vienna) have presented new solutions to this problem.
Nowadays we communicate via radio signals and send electrical pulses through long cables. This could change soon, however: Scientists have been working intensely on developing methods for quantum information transfer. This would enable tap-proof data transfer or, one day, even the linking of quantum computers.
Quantum information transfer requires reliable information transfer from one quantum system to the other, which is extremely difficult to achieve. Independently, two research teams – one at the University of Innsbruck and the other at TU Wien (Vienna) - have now developed a new quantum communication protocol. This protocol enables reliable quantum communication even under the presence of contaminating noise. Both research groups work with the same basic concept: To make the protocol immune to the noise, they add an additional element, a so-called quantum oscillator, at both ends of the quantum channel.
Scientists have conducted quantum communication experiments for a long time. "Researchers presented a quantum teleportation protocol already in the 1990s. It permits transferring the state of one quantum system to another by using optical photons," says Benoit Vermersch, Postdoc in Peter Zoller's group at the University of Innsbruck. This works also over great distances but one has to accept that a lot of the photons are lost and only a tiny fraction reaches the detector.
"Our goal was to find a way to reliably transfer a quantum state from one place to the other without having to do it several times to make it work," explains Peter Rabl from the Atominstitut, TU Wien.