Spin/angular momentum question

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In summary, yes, you can always find an axis along which the spin is an eigenstate, and not a superposition.
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For an electron in an arbitrary spin state, can an axis always be found along which the spin is 1/2 (as opposed to a superposition of 1/2 and -1/2 spins)? What about particles whose spin is 1 or greater? For example, for a spin 1 particle which is in an arbitrary spin state, can one always find an axis along which the spin is either 1 or 0. Or is it possible for a spin 1 particle to be in such a state that it's spin is a superposition of spin 1,0,-1 states along every axis? Moving on to angular momentum, if an electron in a hydrogen atom is in the n=2, l=1 state and in a superposition: a|1>+b|0>+c|-1> where |1>, |0>, |-1> are the eigenstates of L sub z, and a,b,c are arbitrary constants, can one always find an axis along which the angular momentum has a definite value (either 1, 0, or -1) and is not a superposition of states? (I assume that whatever is true for a spin 1 particle is also true for the n=2, l=1 state of the H atom).
 
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  • #2
I think the answer to all your questions is "yes". You can always find an axis where the spin (whatever it is) is an eigenstate along that axis, and not a superposition. Mathematically, the process of finding the axis is equivalent to changing the basis of the spin space.
 
  • #3
Nope,what you're trying to describe is a collapse of an initially entagled state.According to the V-th postulate,the state after measurement will be an eigenstate of the measured observable.

We can't know s*** about a quantum system,before any measurement...

Daniel.

EDIT:I still think he was trying to describe disentanglement. :confused:
 
  • #4
Dextercioby, my question had nothing to do with disentanglement and measurement.
EDIT: How do you know that I'm a "he"? Well, I am, but you couldn't have known that.
 
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Related to Spin/angular momentum question

1. What is spin/angular momentum?

Spin, also known as angular momentum, is a fundamental property of particles that describes their intrinsic rotational motion. It is a quantum mechanical property and is quantized, meaning it can only take on specific values.

2. How is spin/angular momentum measured?

Spin/angular momentum is measured in units of angular momentum, such as joule seconds (J⋅s) or Planck's constant (h). It can be measured using various experimental techniques, such as scattering experiments or nuclear magnetic resonance.

3. What is the difference between spin and orbital angular momentum?

Spin and orbital angular momentum are both forms of angular momentum, but they differ in their origin. Spin is an intrinsic property of particles, while orbital angular momentum is associated with the motion of a particle around an axis. Spin is also quantized, while orbital angular momentum can take on any value.

4. Can spin/angular momentum be changed?

Spin/angular momentum is a conserved quantity, meaning it cannot be created or destroyed. However, it can be transferred between particles through various interactions, such as collisions or electromagnetic interactions.

5. How does spin/angular momentum affect the behavior of particles?

The spin/angular momentum of particles plays a crucial role in determining their behavior and interactions. For example, particles with different spin values will have different properties, such as magnetic moment, and will interact differently with external fields. Spin also plays a role in the stability and energy levels of atoms and molecules.

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