Login Register

Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Bell's theorem - for or against Hidden Variables?
(07-24-2016, 11:20 PM)secur Wrote: But - in Hess's favor -, AFAIK experimenters still haven't rigorously excluded a time-dependent "loophole". Do we really know that entanglement will "work" in other settings than these typical photon-based experiments? In quantum cryptography, computing, and similar discussions, Alice, Bob, and their friends fly all over the universe with entangled particles in boxes, doing amazing tricks with them. But that's all fantasy. The sad truth is that in real labs, over distances of centimeters (not light-years), with the expenditure of millions of dollars, they still can't reliably demonstrate quantum computing. Maybe "Bell non-locality" is just an artifact of the particular experiments done so far? So Hess's main point - that time-correlation, in currently achievable experimental designs, has something to do with it - can't be dismissed so easily. AFAIK, IMHO, and pending further investigation.
The new loophole-free Bell experiments (Delft, Vienna, NIST, all in 2015) do explicitly and rigorously exclude the time-dependence loopholes (as well as the other well-known loopholes: efficiency loophole, coincidence loophole). The distances involved are 1000 meters or more. Their statistical analyses use a martingale technique which I introduced in 2001 https://arxiv.org/abs/quant-ph/0110137https://arxiv.org/abs/quant-ph/0301059, which takes account of arbitrary time variation and memory issues, as long as new settings are chosen at random again and again for each new pair of measurements.

Yes they are photon based (though in Delft, the entangled qubits were in fact associated with electron spins in Nitrogen-vacancy defects in diamond).

Hess' main point was dealt with theoretically 15 years ago, and experimentally last year.

Three loophole free Bell experiments:

Delft:
Hensen et al. (2015)
http://www.nature.com/nature/journal/v52...15759.html
http://arxiv.org/abs/1508.05949
http://arxiv.org/abs/1603.05705

Vienna:
Giustina et al. (2015)
http://journals.aps.org/prl/abstract/10....115.250401
http://arxiv.org/abs/1511.03190

NIST:
Shalm et al. (2015)
http://journals.aps.org/prl/abstract/10....115.250402
http://arxiv.org/abs/1511.03189

Of course, these experiments have their critics and their defects. It is good to see that the Delft experiment was repeated (successfully). The Vienna and NIST experiments can be thought of as independent replicates of one another. So we have two rather different experiments each successfully repeated twice. No doubt more will follow.
Reply


Messages In This Thread
RE: Bell's theorem - for or against Hidden Variables? - by gill1109 - 07-25-2016, 08:19 AM

Forum Jump:


Users browsing this thread: 4 Guest(s)