How Does the Angle Between Axes Affect Spin Correlation in Entangled Particles?

In summary, when measuring the spin of two entangled particles along two separate axes with an angle of "a" between them, the correlation between the two is determined by cos a for spin 1/2 particles (such as electrons) and cos^2 a for spin 1 particles (such as photons). When considering two stern-gerlach devices in a row with particles passing through at an angle of a, the chance of the particle having an up-spin at the second device is determined by cos^2(a/2).
  • #1
gespex
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Given two entangled particles, and the spin of both is measured along two separate axes making an angle of "a", what is the correlation between the two? So how much of the particles will give the same "answer" to the spin measurement?

I've tried googling, but the answers I did find were mathematically too complex for me, though from what I have read it seems it shouldn't be much more than "cos a" or "cos^2 a" for an angle of a < 45 degrees.

Thanks in advance,
gespex
 
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  • #2
gespex said:
Given two entangled particles, and the spin of both is measured along two separate axes making an angle of "a", what is the correlation between the two? So how much of the particles will give the same "answer" to the spin measurement?

I've tried googling, but the answers I did find were mathematically too complex for me, though from what I have read it seems it shouldn't be much more than "cos a" or "cos^2 a" for an angle of a < 45 degrees.

Thanks in advance,
gespex

For spin 1/2 particles, such as electrons: cos a
For spin 1 particles, such as photons: cos^2 a
 
  • #3
Thank you, once again! ;-)
 
  • #4
I have another question about this after all. Imagine two stern-gerlach devices in a row, where the particles with up-spin go through the second with an angle a relative to the first. What is the chance the particle has an up-spin at the second stern-gerlach device as well?

I expected it to be the same (cos a), but I tested it in an applet and it seems to be different after all...

Edit: Never mind, I found the answer. cos^2(a/2).

Thanks in advance
 
Last edited:

1. What is entangled spin correlation?

Entangled spin correlation refers to the phenomenon where the spins of two or more particles are linked in such a way that measuring the spin of one particle can instantaneously affect the spin of the other particles, regardless of the distance between them.

2. How is entangled spin correlation created?

Entangled spin correlation is created when two or more particles are generated together in a quantum state, such as during a particle collision or through the process of spontaneous parametric down-conversion.

3. What is the significance of entangled spin correlation?

Entangled spin correlation is significant because it violates the principles of classical physics and demonstrates the non-local nature of quantum mechanics. It also has potential applications in quantum computing and quantum communication.

4. How is entangled spin correlation measured?

Entangled spin correlation is typically measured through Bell inequality tests, which involve measuring the correlations between the spins of entangled particles in various orientations. These measurements can then be compared to the predictions of classical physics to determine the presence of entanglement.

5. Can entangled spin correlation be used for faster-than-light communication?

No, entangled spin correlation cannot be used for faster-than-light communication. While measuring the spin of one particle may instantaneously affect the spin of another, no actual information or communication can be transmitted through this process.

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