Physicists entangle 15 trillion hot atoms

Jun 9, 2020
1
0
10
Can anyone explain why this isn't an article about conservation of total spin of all the particles in the container? Isn't that a better way to explain it as opposed to quantum entanglement?
 
Jan 3, 2020
140
10
105
"The very notion that particles like protons or electrons are rotating solid objects of size and shape doesn't fit the quantum worldview. And when scientists try to measure a particle's spin, they get one of two answers: up or down. There are no in-betweens in quantum mechanics."

True as far as it goes, but atoms are more complex systems. An atomic electron wavefunction - orbital - has a shape related to its orbital angular momentum [ https://en.wikipedia.org/wiki/Azimuthal_quantum_number ]. But of course the electron itself is point like as a particle.

Can anyone explain why this isn't an article about conservation of total spin of all the particles in the container? Isn't that a better way to explain it as opposed to quantum entanglement?
I think the article author labored more to explain entanglement, which is what the experiment observes, than to explain the total entangled spin of the singlet states, which is what the experiment measures. They use the strength of the applied magnetic field to see the entanglement:

"Fig. 3 Evidence for long-range entanglement. Points show the KF-obtained variances (ΔF^2_z) of the rotating-frame spin component F_z as a function of delay since Fz was last aligned along the laboratory z axis, and thus subject to measurement by Faraday rotation. ... As seen in these data, increased gradient B0 causes a faster relaxation toward the thermal spin state (TSS) value, as is expected for a gas of singlets ..."
 
Jun 10, 2020
1
0
10
It seems they have performed a kind of a Bell measurement similar to what is done in the quantum teleportation protocol. There too, performing a (Bell) measurement entangles somethings and detangles previously entangled parts.
 
Last edited:
Jun 3, 2020
4
1
10
Some explanations in this article (especially the included "Paul Explains" clip) encounter a pitfall which often plagues attempts to explain quantum phenomena: that of using classical terms to describe them. This creates an image of quantum physics of something like "weird classical physics", instead of a whole different realm.

For example, IMHO it's wrong to present uncertainty as "we don't know (or even, cannot know) an electron's exact position" -- this implies that there is such a thing; instead, it's important to stress that the very term "exact position" is meaningless. (Admittedly, even the term "uncertainty" itself is inadequate in this regard).
 
Mar 4, 2020
169
19
105
A rotating helix of current can explain all measured properties. And with a variable pi structure, evade mathematical measurement analysis.
 
Sep 10, 2020
1
0
10
It seems they have performed a kind of a Bell measurement similar to what is done in the quantum teleportation protocol. There too, performing a (Bell) measurement entangles somethings and detangles previously entangled parts.
I hope that they have performed a Bell test. If they have, I wish they would publish the results as I think that a Bell test which did not use particle-antiparticle pairs would not break/exceed the Bell inequalities. I assume that their Bell test would use particle-particle pairs and it would be very useful to show whether the Bell experiment works in the same way using electron-electron pairs rather than using electron-positron pairs..
 

ASK THE COMMUNITY

Latest posts