Loophole-free quantum steering

In summary, the tests of the predictions of quantum mechanics for entangled systems have provided increasing evidence against local realistic theories. 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. Einstein called this "spooky action at a distance". Steering has recently been rigorously formulated as a quantum information task opening it up to new experimental tests. The first loophole-free demonstration of
  • #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.
 
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  • #2
Thanks DrC, will be very interesting to hear what the "loopholer's" say now... are there any left...?
 
  • #3
DevilsAvocado said:
Thanks DrC, will be very interesting to hear what the "loopholer's" say now... are there any left...?

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

:biggrin:
 
  • #4
DrChinese said:
Now don't go baiting, or we'll never hear the end of 'em...

:biggrin:

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

(:biggrin:)
 
  • #5
Was quantum entanglement predicted in theory before it was discovered experimentally?
 

1. What is "loophole-free quantum steering"?

"Loophole-free quantum steering" refers to a phenomenon in quantum mechanics where two particles that are entangled can influence each other's state instantaneously, even if they are separated by a large distance. This effect is considered "loophole-free" because it cannot be explained by any classical theories and is not subject to any known loopholes in experimental setups.

2. How is "loophole-free quantum steering" different from other forms of quantum entanglement?

Unlike other forms of quantum entanglement, "loophole-free quantum steering" is a one-way relationship where one particle can steer the state of the other particle, but not vice versa. This means that the steered particle can be used to transmit information, without the need for a shared reference frame or any classical communication.

3. What is the significance of "loophole-free quantum steering" in quantum computing?

"Loophole-free quantum steering" has significant implications for quantum computing because it allows for the creation of secure communication channels that are resistant to eavesdropping. This is because any attempt to intercept the information being transmitted would be immediately detected by the steered particle, altering its state and alerting the intended recipient.

4. How is "loophole-free quantum steering" being studied and tested?

Scientists are currently studying and testing "loophole-free quantum steering" using various methods, such as Bell tests, quantum teleportation experiments, and quantum key distribution protocols. These experiments involve entangling particles and measuring their states to verify the presence of "loophole-free quantum steering".

5. What are the potential applications of "loophole-free quantum steering"?

The potential applications of "loophole-free quantum steering" are vast and diverse. Some potential uses include secure quantum communication, quantum cryptography, and quantum teleportation for data transfer. It may also have implications for improving the speed and efficiency of quantum computing processes.

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