# Understanding spin and axis in quantum entanglement

1. Nov 15, 2012

### San K

I don't have a good grasp of "spin along axis" topic, so pardon my dumb questions:

1. Does a photon/electron have a different spin across each of the 3 axis?

i understand that the spin of an electron/photon is not the same as that of, say, a ball

2. Gravity can distort time-space (and hence the axis?).

Alice is in a gravity free part of space-time. Bob takes the other entangled photon and is in a space-time region that is distorted by gravity.

If Alice measures the spin of her entangled photon along say the "x-axis"

how does Bob figure out what his "x-axis" is? does Bob simply make adjustments for the new Cartesian system based on the formulas (for distortion of space time by gravity)?

3. If a photon is travelling along x-axis, does it have one spin each for each of the three axis? thus a total of 3 spins....if you are making calculations in the Cartesian system

Last edited: Nov 15, 2012
2. Nov 15, 2012

### Bill_K

Good question. Bob's particle must be noninteracting until it is measured. In a curved spacetime this means the particle follows a geodesic, and its spin axis is parallel transported. So although each of Bob's axes x, y, z may not be "the same" as Alice's, they correspond uniquely to those of Alice.

3. Nov 15, 2012