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Loophole-free quantum steering

  1. Nov 4, 2011 #1

    DrChinese

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    Yet another nail in the coffin for local realistic theories:

    [URL [Broken] quantum steering (2011)
    Bernhard Wittmann, Sven Ramelow, Fabian Steinlechner, Nathan K. Langford, Nicolas Brunner, Howard Wiseman, Rupert Ursin, Anton Zeilinger[/url]

    "Tests of the predictions of quantum mechanics for entangled systems have provided increasing evidence against local realistic theories 1-6. However, there still remains the crucial challenge of simultaneously closing all major loopholes - the locality, freedom-of-choice, and detection loopholes - in a single experiment. An important sub-class of local realistic theories can be tested with the concept of "steering". The term steering was introduced by Schrodinger in 1935 for the fact that entanglement would seem to allow an experimenter to remotely steer the state of a distant system 7. Einstein called this "spooky action at a distance" 8. Steering has recently been rigorously formulated as a quantum information task opening it up to new experimental tests 9-11.

    Here, we present the first loophole-free demonstration of steering by violating three-setting quadratic steering inequality, tested with polarization entangled photons shared between two distant laboratories. Our experiment demonstrates this effect while simultaneously closing all loopholes by a large separation, ultra-fast switching, quantum random number generation, and high, overall detection efficiency. Thereby, we exclude - for the first time loophole-free - an important class of local realistic theories. As well as its foundational importance 9,10, loop-hole-free steering also allows the secure distribution of quantum entanglement from an untrusted party 12."

    Although this apparently does not provide simultaneous loophole-free rejection of all LR theories, I am not sure what ones are left standing at this point.
     
    Last edited by a moderator: May 5, 2017
  2. jcsd
  3. Nov 4, 2011 #2

    DevilsAvocado

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    Thanks DrC, will be very interesting to hear what the "loopholer's" say now... are there any left...?
     
  4. Nov 4, 2011 #3

    DrChinese

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    Now don't go baiting, or we'll never hear the end of 'em...

    :biggrin:
     
  5. Nov 4, 2011 #4

    DevilsAvocado

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    okay boss ... I’ll go easy on this one ... no sweat ... it’s just ... I kinda miss those "1500 posts to nowhere"... :redface:

    (:biggrin:)
     
  6. Nov 4, 2011 #5
    Was quantum entanglement predicted in theory before it was discovered experimentally?
     
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