Chinese Physicists Smash Distance Record (again)For Teleportation

Discussion in 'China' started by cir, May 12, 2012.

  1. cir

    cir Senior Member Senior Member

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    The ability to teleport photons through 100 kilometres of free space opens the way for satellite-based quantum communications, say researchers

    kfc 05/11/2012

    Teleportation is the extraordinary ability to transfer objects from one location to another without travelling through the intervening space.

    The idea is not that the physical object is teleported but the information that describes it. This can then be applied to a similar object in a new location which effectively takes on the new identity.

    And it is by no means science fiction. Physicists have been teleporting photons since 1997 and the technique is now standard in optics laboratories all over the world.

    The phenomenon that makes this possible is known as quantum entanglement, the deep and mysterious link that occurs when two quantum objects share the same existence and yet are separated in space.

    Teleportation turns out to be extremely useful. Because teleported information does not travel through the intervening space, it cannot be secretly accessed by an eavesdropper.

    For that reason, teleportation is the enabling technology behind quantum cryptography, a way of sending information with close-to-perfect secrecy.

    Unfortunately, entangled photons are fragile objects. They cannot travel further than a kilometre or so down optical fibres because the photons end up interacting with the glass breaking the entanglement. That severely limits quantum cryptography's usefulness.

    However, physicists have had more success teleporting photons through the atmosphere. In 2010, a Chinese team announced that it had teleported single photons over a distance of 16 kilometres. Handy but not exactly Earth-shattering.

    Now the same team says it has smashed this record. Juan Yin at the University of Science and Technology of China in Shanghai, and a bunch of mates say they have teleported entangled photons over a distance of 97 kilometres across a lake in China.

    That's an impressive feat for several reasons. The trick these guys have perfected is to find a way to use a 1.3 Watt laser and some fancy optics to beam the light and receive it.

    Inevitably photons get lost and entanglement is destroyed in such a process. Imperfections in the optics and air turbulence account for some of these losses but the biggest problem is beam widening (they did the experiment at an altitude of about 4000 metres). Since the beam spreads out as it travels, many of the photons simply miss the target altogether.

    So the most important advance these guys have made is to develop a steering mechanism using a guide laser that keeps the beam precisely on target(this technology would surely find its use in laser weapons). As a result, they were able to teleport more than 1100 photons in 4 hours over a distance of 97 kilometres.

    That's interesting because it's the same channel attenuation that you'd have to cope with when beaming photons to a satellite with, say, 20 centimetre optics orbiting at about 500 kilometres. "The successful quantum teleportation over such channel losses in combination with our high-frequency and high-accuracy [aiming] technique show the feasibility of satellite-based ultra-long-distance quantum teleportation," say Juan and co.

    So these guys clearly have their eye on the possibility of satellite-based quantum cryptography which would provide ultra secure communications around the world. That's in stark contrast to the few kilometres that are possible with commercial quantum cryptography gear.

    Of course, data rates are likely to be slow and the rapidly emerging technology of quantum repeaters will extend the reach of ground-based quantum cryptography so that it could reach around the world, in principle at least.

    But a perfect, satellite-based security system might be a useful piece of kit to have on the roof of an embassy or distributed among the armed forces.

    Something for western security experts to think about.

    Ref: arxiv.org/abs/1205.2024: Teleporting Independent Qubits Through A 97 Km Free-Space Channel

    Chinese Physicists Smash Distance Record For Teleportation  - Technology Review
     
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  3. cir

    cir Senior Member Senior Member

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    As per previous reports, China is to launch her first quantum satellite in 2015.

    The satellite will be designed、built and operated by the same team that carried out the test above.

    PS It is the University of Science and Technology of China in Hefei, Anhui province, not in Shanghai.

    PSS China is obviously in the midst of setting up quite a few Sci. & Tech. universities. After the recent establisment of the South China Uni. of Sci. & Tech.,It is Shanghai‘s turn to have its own Uni. of Sci. & Tech. Same for the creation of the North China Uni. of Sci. & Tech.
     
  4. cir

    cir Senior Member Senior Member

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    Tech|5/11/2012 @ 11:58AM |11,706 views

    Chinese Researchers Quantum Teleport Photons Over 60 Miles

    Since 1997, researchers have been able to quantum teleport photons with a major record being set by researchers at the University of Science and Technology of China in Shanghai. In 2010, that team successfully teleported a photon over 16km. Now that same team has released new findings, in which they claim to have teleported photons nearly 100km, or over 60 miles.

    Now, quantum teleportation isn’t quite the same thing as the teleportation in Star Trek. When researchers teleport a photon, they aren’t teleporting the actual photon, but rather the information contained in it through quantum entanglement. In essence, the second photon at the end of the teleport becomes the first one – or at least, it becomes an identical qubit of information. So the information is exchanged without actually travelling through the intervening distance.

    (If that sounds bizarre and frightening, you’re in good company. Albert Einstein understatedly called the process of quantum entanglement “spooky action at a distance.”)

    The challenge for quantum teleportation is that it has to be done in free space. Fiberoptics don’t work, because once you get to distances over about 1 kilometer, the fiber absorbs so much light that the information is lost. But while a fiberoptic cable can keep photons focused, moving over free space means using lasers – which inevitably causes the beam of light to spread out over time. However, using a powerful laser along with some other optical equipment, the researchers here developed a technique to keep the beam focused over the course of 97km, and successfully achieved quantum teleportation.

    The ability to teleport information means that it could be possible to have worldwide communications that are impossible to listen in on. Because in quantum teleportation, the information doesn’t travel over any intervening distances, there’s no way to tap into the communication. As Technology Review notes, “these guys clearly have their eye on the possibility of satellite-based quantum cryptography which would provide ultra secure communications around the world.”

    That technology is still a long way off, however. Despite the fact that the communication developed here is very efficient, it’s also very slow. They’ll also have to keep improving the distance. 60 miles for teleportation is a new record. It’s impressive. But communications satellites are typically in geosynchronous orbit – 22,236 miles up in the air.

    Still, while there’s still a long way to go before we have true quantum-teleportation powered communications, this is a huge step in that direction.

    Chinese Researchers Quantum Teleport Photons Over 60 Miles - Forbes
     
  5. Dovah

    Dovah Untermensch Senior Member

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    Bah! Theory of entanglement. The guys in Switzerland did it long back.
     
  6. Ray

    Ray The Chairman Defence Professionals Moderator

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    Nothing could beat this.

    Experiment breaks speed of light barrier

    High quality global journalism requires investment. Please share this article with others using the link below, do not cut & paste the article. See our Ts&Cs and Copyright Policy for more detail. Email [email protected] to buy additional rights. Experiment breaks speed of light barrier - FT.com

    An experiment at Cern, the world’s largest physics laboratory, has shown particles apparently travelling faster than light – and in the process smashing what has been a fundamental tenet of science for more than a century.

    On Thursday night Antonio Ereditato, leader of the Opera experiment at the lab in Switzerland, said beams of neutrinos, or subatomic particles, consistently arrived about 60 nanoseconds sooner on a 730km journey from Cern outside Geneva to the Gran Sasso underground lab in central Italy than if they would have been travelling at the speed of light – about 300,000km per second.

    Experiment breaks speed of light barrier - FT.com
     
  7. Ray

    Ray The Chairman Defence Professionals Moderator

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    And the famous Fermilab

    Fermilab's Tevatron was a landmark particle accelerator; at 3.9 miles (6.3 km) in circumference, it was the world's second largest energy particle accelerator (CERN's Large Hadron Collider is 27 km in circumference), until being shut down on September 30, 2011. In 1995, both the CDF and DØ (detectors which utilize the Tevatron) experiments announced the discovery of the top quark.

    A quark is an elementary particle and a fundamental constituent of matter. Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei. Due to a phenomenon known as color confinement, quarks are never directly observed or found in isolation; they can only be found within baryons or mesons.
     
  8. Dovah

    Dovah Untermensch Senior Member

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    Sir, the results of that experiment were erroneous, certain wires etc were lose.
     
  9. what is a quantum satellite?
     
  10. opkeyen

    opkeyen Regular Member

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    Modern philosophy of quantum mechanics explanation, let Buddhism closer to science, so India is great, as early as 2000 years ago appeared to recognize the universe truth.
     
  11. cir

    cir Senior Member Senior Member

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    Breaking their own record, Chinese researchers teleport photons 97 kilometers

    May 11, 2012

    Researchers announced recently they successfully teleported photons across more than 62 miles.

    Scientists have long eyed the elusive and seemingly impossible goal of teleportation. The objective of such engineering research was not to teleport a physical object, but rather the information describing it. Such data could then serve as a framework applied to a new entity at a separate location, one that would subsequently assume that identity, MIT's Technology Review reports.

    Physicists have been teleporting photons for the better part of the past 15 years. They have been able to do so because of quantum entanglement, a concept that scientists still do not entirely understand.

    Quantum entanglement is a physical characteristic associated with the connections that are sometimes shared between two discrete quantum systems. The general study of entanglement, a term Schrödinger applied to the relationship, is essentially the basis of quantum information theory, according to the Stanford Encyclopedia.

    Though it undoubtedly remains a mysterious force, quantum entanglement allows for two quantum objects to share the same existence, even though they are dispersed in space. Teleporting data has particularly sparked the interest of researchers throughout the globe, as the ability to transfer information without the risk of interception or eavesdropping.

    New engineering tools have aimed to improve the efficiency and ultimately ensure the success of the emergent field of physics, known as quantum cryptography. Researchers have had to overcome myriad hurdles as they sought to teleport entangled photons across optical fibers over distances longer than two-thirds of a mile. By teleporting photons through the atmosphere, however, they have had significantly better luck, according to Technology Review.

    Chinese scientists said in 2010 that they had teleported individual photons 16 kilometers, roughly equivalent to 10 miles. The same team of researchers said this week that they had broken their own record by teleporting photons over a distance of more than 97 kilometers, or approximately 60 miles. Popular Science reports that the feat is the latest in a series of stunning discoveries within the field.

    The team of researchers, who are affiliated with the University of Science and Technology of China in Shanghai, used a 1.3-Watt laser and teleported the particles over a lake in China that is located at an altitude of more than 13,000 feet. As a result of their use of a laser, the scientists had to first ascertain how to prevent photons from getting lost when the device's beam widens.

    They surmounted that barrier by designing a steering system that prevents the laser's beam from broadening. According to the team, they were able to teleport 1,100 photons over a distance of 97 kilometers in only four hours. Juan Yin, one of the scientists who participated in the research, said that the experiment's successful results suggested that scientists could one day teleport photons over even longer distances, with the potential to reach space-based satellites.

    "Besides being of fundamental interest, our result represents an important step towards a global quantum network," the team said. "The successful quantum teleportation over such channel losses in combination with our high-frequency and high-accuracy [aiming] technique show the feasibility of satellite-based ultra-long-distance quantum teleportation."

    The Chinese scientists published their findings, "Teleporting Independent Qubits Through a 97 Kilometer Free-Space Channel," this week:[1205.2024] Teleporting independent qubits through a 97 km free-space channel
     

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