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Entanglement Between Photons that have Never Coexisted

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Sun, 2013-05-26 20:12

Arenamontanus Arenamontanus's picture

Entanglement Between Photons that have Never Coexisted

Even Science magazine says "Now they're just messing with us." Physicists have successfully entangled photons that exist at different points in time: http://news.sciencemag.org/sciencenow/2013/05/physicists-create-quantum-... http://arxiv.org/abs/1209.4191 This is by no means unexpected, given past results, but it is still mindbending. And another reason for me to be cautious about allowing PCs to use QE comms :-) And incidentally, the headline "String theory may limit space brain threat" on the New Scientist site is one of the funnier I have seen in a while about a serious paper. This is about a paper showing that - assuming certain things about string theory and baby universes - randomly created Boltzman brains will not be in the majority. http://www.newscientist.com/article/mg21829184.400-string-theory-may-lim... http://arxiv.org/abs/1211.7021 Oh, and those time crystals? ( http://arxiv.org/abs/1202.2539 ) Old-fashioned, now we have phase space crystals with quasienergy: http://arxiv.org/abs/1305.1800 Ah, modern physics! It can outweird most fiction. (Oh, and this might be good background for space navigation: using pulsars as interplanetary GPS http://www.technologyreview.com/view/515321/an-interplanetary-gps-using-... )

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Mon, 2013-05-27 00:15

The Green Slime The Green Slime's picture

My cat's breath smells like

My cat's breath smells like cat food.

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[img]http://boxall.no-ip.org/img/iso_userbar.jpg[/img] [img]http://boxall.no-ip.org/img/aliens_userbar.jpg[/img] [i]Time will perfect matter.[/i]

Mon, 2013-05-27 02:44

Arenamontanus Arenamontanus's picture

Aha, so by smelling you

Aha, so by smelling you collapsed its wavefunction! EDIT: Actually, if the theorye that smell uses quantum interactions to detect molecular shape are true ( http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0055780 ), then you got entangled with your cat!

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Thu, 2013-05-30 19:01

The Green Slime The Green Slime's picture

...my cat's name is Mittens.

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[img]http://boxall.no-ip.org/img/iso_userbar.jpg[/img] [img]http://boxall.no-ip.org/img/aliens_userbar.jpg[/img] [i]Time will perfect matter.[/i]

Thu, 2013-05-30 23:42

Decivre

I'm pretty sure this topic

I'm pretty sure this topic has broken The Green Slime. This does have me very interested in the ramifications. Does this mean that the spin of future particles may affect past ones, or is this a sort of "one-sided entanglement" where the future particle is basically mimicking the spin of the paired particle that once existed? Would we even be able to tell the difference between the two possibilities?

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Transhumans will one day be the Luddites of the posthuman age. [url=http://bit.ly/2p3wk7c]Help me get my gaming fix, if you want.[/url]

Fri, 2013-05-31 03:54

Arenamontanus Arenamontanus's picture

Decivre wrote:I'm pretty sure

Decivre wrote:
I'm pretty sure this topic has broken The Green Slime.

The problem is that The Green Slime is a macroscopic object and has already been observed. Had it been quantum we could just reverse the operations and restore it to its original state.

Decivre wrote:
This does have me very interested in the ramifications. Does this mean that the spin of future particles may affect past ones, or is this a sort of "one-sided entanglement" where the future particle is basically mimicking the spin of the paired particle that once existed? Would we even be able to tell the difference between the two possibilities?

As far as I understand, it is real entanglement, not just fake one. An operation on the future spin (like using it in quantum encryption by either viewing it through a normal or slanted polarization filter) will mean the state of the past one when measured will be compatible, even if the choice of the operation has not yet been decided when you do the experiment that measures it in the past. But quantum entanglement always looks like a conspiracy: you measure horizontal/vertical or slanted1/slanted2, get a random-looking result, and it is only when you put your result together with the result at the other end you see that they were exactly compatible. In a sense this is entirely reasonable: quantum stuff is nonlocal, so if quantum entanglement interactions could happen anywhere in space they could happen anywhere in time too.

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Fri, 2013-05-31 04:11

Decivre

Arenamontanus wrote:As far as

Arenamontanus wrote:
As far as I understand, it is real entanglement, not just fake one. An operation on the future spin (like using it in quantum encryption by either viewing it through a normal or slanted polarization filter) will mean the state of the past one when measured will be compatible, even if the choice of the operation has not yet been decided when you do the experiment that measures it in the past. But quantum entanglement always looks like a conspiracy: you measure horizontal/vertical or slanted1/slanted2, get a random-looking result, and it is only when you put your result together with the result at the other end you see that they were exactly compatible. In a sense this is entirely reasonable: quantum stuff is nonlocal, so if quantum entanglement interactions could happen anywhere in space they could happen anywhere in time too.

I wasn't saying it was some sort of fake entanglement, just a variation of entanglement. One particle that influences the spin of another, rather than bi-directional influence. Considering how much we are learning in the field of entanglement, it would certainly be an interesting proposition. I'm just looking for a proposition that would allow for such an interesting phenomenon that would still be compatible with causality, with or without the transmission of information.

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Transhumans will one day be the Luddites of the posthuman age. [url=http://bit.ly/2p3wk7c]Help me get my gaming fix, if you want.[/url]

Fri, 2013-05-31 04:27

Arenamontanus Arenamontanus's picture

As far as I understand, there

As far as I understand, there is no difference between affecting the entanglement with the past or the future particle. Causality might be more about the ordering of events (what must come before something else in a directed network of interacting events) than timing of events.

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