Researchers (...) were able to generate frequency-bin entangled narrowband biphotons from spontaneous four-wave mixing (SFWM) in cold atoms with a double-path configuration, where the phase difference between the two spatial paths can be controlled independently and non-locally.
For me this is too complex a description to understand what is going on.
2) Frequency entanglement:
Entanglement can be had from many properties. The one most are 'familiar' with is probably polarization, but you can entangle spin, position, momentum....
Position only for bosons only, obviously?
Would there be a restriction on the phase angles of the two entangled photons?
@Seeker, why would there be only entanglement on position for bosons? Not sure I understand your reasoning here.I was thinking fermions could not be entangled at the same position because of the Pauli Exclusion principle. Presuming that's what entanglement on position means. Probably misunderstood the Pauli Exclusion principle though.
@Seeker, Pauli Exclusion doesn't prohibit two fermions being emitted from the same particle (fermion or boson) at the same time. For example, a decaying neutron emits an electron and an electron antineutrino, both fermions. More complex examples involve two fermions of identical nature emerging from the interaction, with momenta that add to the original momentum of the original particle; and these two fermions would be entangled on position/momentum as well as energy/time (or as in this article, frequency/time) degrees of freedom.By position I assume you mean the position at emission or positon of the entangled fermions then and thereafter? That is I'm thinking the two fermions go off to different positions after emission.
They have to split the momentum, and that means they are entangled on the position/momentum degree of freedom.So does that mean their momentum has equal magnitude but opposite direction until they decohere?
Not necessarily, they might not split it 50/50, but you can think of it that way and not be far wrong. Note that if their masses are not equal they will have different vectors, but they'll still have to vector add to the original momentum of the progenitor particle.They have to split the momentum, and that means they are entangled on the position/momentum degree of freedom.So does that mean their momentum has equal magnitude but opposite direction until they decohere?
Does, or could, gravity decohere entangled particles?Good question. Unfortunately without a theory of quantum gravity we can't tell.
Good question. Unfortunately without a theory of quantum gravity we can't tell.If gravity warps spacetime wouldn't it similarly affect the wave fundtion?
I was thinking virtual particles have something to do with Hawking radiation?Hawking radiation is a process by which virtual interactions are manifested as real particles by extracting energy from a black hole's gravity field at the event horizon. They are then no longer virtual.
So these real particles are not entangled?With what? If something is inside a black hole you can never check for entanglement. You can't measure it.
entanglement runs over quantum vacuum http://article.sc....13.htmlPer your reference time t means numerical order of material changes. I don't see it. Changes yes. Material? The material really doesn't have to change, it's the spatial configuration of the materials. Or, I would say, the ratio between changes in spatial configurations. To be meaningful you need to have a reference - days, seconds, or whatever. At any rate a ratio is not a dimension. This ratio is not even a ratio of dimensions. Just had to get that off my chest. Thanks.
AmritSorli
May 8, 2017