Polarization, Bell, and spin of photons

In summary: It is because photons have no mass, so they have only the helicity (+1 or -1) with values of +1 or -1.
  • #1
jk22
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i have the following questions: Bell inequalities use spin 1/2 matrices and experiments use photons. Is then the electric field horizontal or vertical after the measurement with a polarizer in other words can we assimilate the orientation of the field with a vector in the hilbert space ? How does this correspond to the quantum rule that the endstate should be normalized if the photon after measurment has less intensity ?

But photons are spin 1 particle a boson, so then which state of the electrical field corresponds to the third quantum measurement result ?

Thanks.
 
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  • #2
The three measurements in these experiments are made by orienting the polarizer at three different angles. No matter what the polarization of the incoming photon, there are only two possible outcomes (in the idealized situation) when it encounters the polarizer: either it passes through the polarizer and its polarization is now aligned with the polarizer; or it is absorbed.

There is a 100% probability that one of those two outcomes will happen. If the photon passes the polarizer, then we renormalize its wave function to reflect the new state: there is a 100% probability that the photon is in a state consistent with it having passed the polarizer.

(You may want to spend some time understanding the quantum mechanical description of single-polarizer experiments before you dig into the subtleties of the two-polarizer experiments involved in tests of Bell's theorem)
 
  • #3
I meant for spin 1 we measure the polarization once we can get 1,-1 and 0 which corresponds to polarization let say vertical horizontal and what does 0 corresponds to ?
 
  • #4
jk22 said:
I meant for spin 1 we measure the polarization once we can get 1,-1 and 0 which corresponds to polarization let say vertical horizontal and what does 0 corresponds to ?

The polarization of a photon has nothing to do with its spin.

You measure the polarization of a photon in a given direction by using the procedure I described above: send the photon through a polarizer oriented in the direction of interest. There are only two possible results, passing and not passing.
 
  • #6
So the fact that helicity has only two value implies that it can be modelized with pauli matrices.
 

1. What is polarization of photons?

Polarization of photons refers to the orientation of the electric field oscillations of a photon. It can be linear, circular, or elliptical, and is determined by the direction and amplitude of the electric field vector.

2. What is the Bell test and how does it relate to photons?

The Bell test is a scientific experiment designed to test the principles of quantum mechanics and determine whether there is a hidden variable determining the behavior of particles. It relates to photons because it can be used to test the phenomenon of entanglement, where two particles are connected in a way that their properties are dependent on each other, even when separated by large distances.

3. Can photons have spin?

Yes, photons can have spin, which refers to the intrinsic angular momentum of a particle. However, unlike particles with mass, the spin of a photon is always fixed at a value of 1, and cannot be changed through interactions with other particles.

4. How is the spin of photons related to their polarization?

The spin of a photon is related to its polarization through the concept of spin angular momentum. This is the component of the photon's spin that is aligned with its direction of motion. For example, a photon with circular polarization will have a spin component perpendicular to its direction of motion.

5. What is the significance of polarization and spin of photons in quantum computing?

Polarization and spin of photons are crucial in quantum computing because they can be used as qubits, the basic unit of information in a quantum computer. The ability to control and measure the polarization and spin of photons allows for the manipulation of quantum states, which is essential for performing calculations in a quantum computer.

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