"Spooky action at a distance" proven now:

A particle superpositioned with itself!

http://phys.org/news/2015-03-quantum-einstein-spooky-action-distance.html

Originally posted by sonhouse
A particle superpositioned with itself!

http://phys.org/news/2015-03-quantum-einstein-spooky-action-distance.html

""Spooky action at a distance" proven now:"

But this is well proven from before, isn't it?

"A particle superpositioned with itself!"

But this is quite a new insight! A particle plays with itself!

Originally posted by FabianFnas
A particle plays with itself!

And it's not ashamed about it? Clearly an atheist particle.

Originally posted by FabianFnas
""Spooky action at a distance" proven now:"

But this is well proven from before, isn't it?

"A particle superpositioned with itself!"

But this is quite a new insight! A particle plays with itself!

There's the Alain Aspect experiment from the late eighties, but people argued with it. It's not clear to me from the phys.org article what they've done, phys,org where too busy talking about spooky action at a distance and didn't explain what the experiment actually did. Without reading the paper it's not clear to me what they've shown.

If they've "proved Einstein wrong" it means they've ruled out hidden variable theories, so the deBroglie-Bohm interpretation is looking in trouble assuming phys.org hasn't misrepresented the experiment. This leaves the Copenhagen interpretation and the Many Worlds interpretation as the remaining viable candidates. There are other interpretations, but they are either hidden variable theories or rehashes of the Copenhagen or many worlds interpretations.

Theoretically there is nothing new here. It's just a novel (and pretty nice) experimental way of demonstrating it.

Originally posted by DeepThought
There's the Alain Aspect experiment from the late eighties, but people argued with it. It's not clear to me from the phys.org article what they've done, phys,org where too busy talking about spooky action at a distance and didn't explain what the experiment actually did. Without reading the paper it's not clear to me what they've shown.

If they've " ...[text shortened]... re either hidden variable theories or rehashes of the Copenhagen or many worlds interpretations.

The e-print is available here:

http://arxiv.org/abs/1412.7790

Originally posted by KazetNagorra
The e-print is available here:

http://arxiv.org/abs/1412.7790

Thanks, I'll give it a read.

I've skim read the paper. I think this is mainly of technological importance. I don't think it alters the status of any of the interpretations of Quantum Mechanics. The homodyne measurement involves interference patterns between wavefunctions and, as I understand it, in de Broglie-Bohm the pilot waves (wavefunction) are meant to interact this way anyway the local presence of the particle isn't required for it to happen. They explicitly state in the discussion that it is not a Bell Inequality violation test. So I don't think that this does anything to rule out different interpretations of Quantum Mechanics.

Originally posted by DeepThought
I've skim read the paper. I think this is mainly of technological importance. I don't think it alters the status of any of the interpretations of Quantum Mechanics. The homodyne measurement involves interference patterns between wavefunctions and, as I understand it, in de Broglie-Bohm the pilot waves (wavefunction) are meant to interact this way anyw ...[text shortened]... don't think that this does anything to rule out different interpretations of Quantum Mechanics.

What do they mean by this statement:

"We demonstrate this single-particle spooky action, for the first time with no efficiency loophole"

What do they mean by 'efficiency loophole'?

Originally posted by sonhouse
What do they mean by this statement:

"We demonstrate this single-particle spooky action, for the first time with no efficiency loophole"

What do they mean by 'efficiency loophole'?

I'm a theorist and this is an experimental detail, I'll do by best but this is something I don't have much intuition for, so this is the kind of thing I can misunderstand easily. The paper talks about Bob and Alice as two experimenters in separate labs. Some experiments require post-selection, I think what this means is that Bob needs information from Alice about which wavefunctions she's manipulated. The way they put it is that Bob needs to trust Alice to do the experiment properly. In this experiment Bob does not need to trust Alice to work out if a photon's had a homodyne measurement done on it. So there is no loss in (experimental) efficiency.

Originally posted by DeepThought
I'm a theorist and this is an experimental detail, I'll do by best but this is something I don't have much intuition for, so this is the kind of thing I can misunderstand easily. The paper talks about Bob and Alice as two experimenters in separate labs. Some experiments require post-selection, I think what this means is that Bob needs information from ...[text shortened]... oton's had a homodyne measurement done on it. So there is no loss in (experimental) efficiency.

Like not needing to introduce outside information beforehand?

Originally posted by sonhouse
Like not needing to introduce outside information beforehand?

Well, this is after the fact information, as I understand what it means is that they didn't have to use careful timing tricks to make sure that the photon tinkered with by one observer was the photon the other observer did the position measurement on. It's easy for me to be wrong about this, the paper assumes various bits of background I don't have.