Conservation of Total Spin in the Stern Gerlach Experiment

In summary, the conversation discusses the possibility of obtaining the same result for the spin state of individual particles after a sequence of operations involving the Stern Gerlach Experiment and photon interaction. It is concluded that while the total spin is conserved, there is no known correlation between photon polarization and spin of individual particles in this scenario.
  • #1
CassiopeiaA
31
0
I just started reading Stern Gerlach Experiment and this thought crossed my mind. Totally a hypothetical question. If I pass an electron and positron through separate SG apparatuses, I will know in which spin state each particle has collapsed. But afterwords I let electron-positron pair annihilate to produce 2 photons. I let these photon Interact with each other and again produce an electron-positron pair. So, if I again check the spin state of these particles separately, in the same direction as before, will I get the same result or is it again completely random?

P.S. I am just a school student trying to learn something difficult for me to understand. So please spare my ignorance.
 
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  • #2
CassiopeiaA said:
if I again check the spin state of these particles separately, in the same direction as before, will I get the same result

No. The sequence of operations you describe will conserve the total spin, but it will not conserve the individual spins of the particles.
 
  • #3
PeterDonis said:
No. The sequence of operations you describe will conserve the total spin, but it will not conserve the individual spins of the particles.
Oh Okay. So there is no known correlation between photon polarization and spin of electron-positron pair in case of pair production?
 
  • #4
CassiopeiaA said:
So there is no known correlation between photon polarization and spin of electron-positron pair in case of pair production?

Not for the individual particles. As I said, only the total spin is conserved.
 
  • #5
PeterDonis said:
Not for the individual particles. As I said, only the total spin is conserved.

Okay thanks.
 

1. What is the Stern Gerlach Experiment?

The Stern Gerlach experiment is a classic experiment in quantum mechanics that was first performed in 1922 by Otto Stern and Walther Gerlach. It involves passing a beam of neutral particles, such as atoms or subatomic particles, through an inhomogeneous magnetic field and studying the deflection of the particles.

2. What was the purpose of the Stern Gerlach Experiment?

The purpose of the Stern Gerlach experiment was to study the intrinsic magnetic moment of atoms and to test the predictions of quantum mechanics. It was also used to demonstrate the quantization of spin, which is a property of particles that can be thought of as an intrinsic angular momentum.

3. How does the Stern Gerlach Experiment work?

The experiment works by passing a beam of particles through a region with an inhomogeneous magnetic field. The field causes the particles to experience a force that is dependent on their spin orientation. This results in a splitting of the beam into two or more distinct paths, which can be observed on a detector screen.

4. What were the results of the Stern Gerlach Experiment?

The results of the experiment were unexpected at the time and provided strong evidence for the existence of quantized spin states in particles. The beam of particles was split into two distinct paths, with some particles being deflected up and others being deflected down, indicating the existence of two spin states.

5. How did the Stern Gerlach Experiment impact the development of quantum mechanics?

The Stern Gerlach experiment played a crucial role in the development of quantum mechanics by providing experimental evidence for the quantization of spin and the existence of two distinct spin states in particles. It also helped to solidify the concept of wave-particle duality and led to further investigations into the behavior of particles on a quantum level.

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