Entanglement Experiments: Sources & Detection

[yuiop]

In another thread https://www.physicsforums.com/showpost.php?p=3143182&postcount=34 it is stated that:

Experiments show that particles can be entangled that have never interacted. QM predicts this, but your ideas wouldn't. Also, particles can become entangled after they are detected. Hardly the kind of thing that would happen if there was a common event responsible for entanglement.

So far all entanglement experiments I have read about, have a single common source, usually a pump laser passed through a BBO crystal. Can anyone provide references for actual experiments that demonstrate entanglement of particles that have never interacted or demonstrates that particles that were not entangled before detection, become entangled after detection?

 

[ThomasT]

These papers were referenced in DrC's Entangled "Frankenstein" Photons paper:

T. Jennewein, G. Weihs, J. Pan, A. Zeilinger, Experimental Nonlocality Proof of Quantum
Teleportation and Entanglement Swapping (2002).
http://arxiv.org/PS_cache/quant-ph/pdf/0201/0201134v1.pdf

R. Kaltenbaek, R. Prevedel, M. Aspelmeyer, A. Zeilinger, High-fidelity entanglement
swapping with fully independent sources (2008).
http://arxiv.org/PS_cache/arxiv/pdf/0809/0809.3991v3.pdf

 

[Ken G]

And of course there is the entanglement of identical particles, which usually doesn't do much but can change the energy of a multi-electron atom (there's the "exchange energy" when the requirement that the exchange of fermions should change the sign of the wavefunction, from whence also comes the Pauli exclusion principle). So for example, when a new electron that just got created, say in a pair creation episode, arrives in a white dwarf, it immediately encounters degeneracy pressure because of its entanglement with all the other electrons already there. Of course, the above language is fundamentally incorrect because it pretends we can say which is the electron that is the new arrival, which in fact we cannot-- it gets lost in a sea of indistinguishable electrons, which is one of the most prevalent forms of entanglement. I would say it requires no "interaction" for it to be present, it is an expression of the fact that at some level, the creation of any new electron makes reference to whatever information is contained in the entire electron distribution everywhere in the universe, in the sense that no individual electron is allowed to carry its "own information" independently of all those others, since they are all indistinguishable.

 

[DrChinese]

These papers were referenced in DrC's Entangled "Frankenstein" Photons paper:

T. Jennewein, G. Weihs, J. Pan, A. Zeilinger, Experimental Nonlocality Proof of Quantum
Teleportation and Entanglement Swapping (2002).
http://arxiv.org/PS_cache/quant-ph/pdf/0201/0201134v1.pdf

R. Kaltenbaek, R. Prevedel, M. Aspelmeyer, A. Zeilinger, High-fidelity entanglement
swapping with fully independent sources (2008).
http://arxiv.org/PS_cache/arxiv/pdf/0809/0809.3991v3.pdf

Thanks for that!

 

[yoda jedi]

These papers were referenced in DrC's Entangled "Frankenstein" Photons paper:

T. Jennewein, G. Weihs, J. Pan, A. Zeilinger, Experimental Nonlocality Proof of Quantum
Teleportation and Entanglement Swapping (2002).
http://arxiv.org/PS_cache/quant-ph/pdf/0201/0201134v1.pdf

R. Kaltenbaek, R. Prevedel, M. Aspelmeyer, A. Zeilinger, High-fidelity entanglement
swapping with fully independent sources (2008).
http://arxiv.org/PS_cache/arxiv/pdf/0809/0809.3991v3.pdf

regard the first paper it seem that the secuence of the events has no influence on the results, can't change it, the causality it lost.

"Thus depending on Alice’s later measurement, Bob’s earlier results either indicate that photons 0 and 3 were entangled or photons 0 and 1 and photons 2 and 3.
This means that the physical interpretation of his results depends on Alice’s later decision."