Measuring Spin in the Stern Gerlach Experiment

In summary, the conversation discusses the measurement of spin eigenstates and the relationship between time-dependent and time-independent Schrodinger equations. It is mentioned that the state vector is time-dependent, but the eigenstates of energy are stationary. However, there are shared eigenstates of energy and spin that remain constant over time.
  • #1
klen
41
1
When we are measuring the spin of the electron in the experiment, we choose the spin property as its eigen state for the measurement. The eigen vectors corresponding to these states could be time dependent. Can we still break the problem into solving time independent Schrodinger Equation and then multiplying by a time dependent function, like we do for the case of measurement of energy? How do we calculate the spin eigen vectors using Schrodinger Equation?
 
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  • #2
In the representation you are talking about, it is the state vector that is time dependent... not the eigenstates.
##\psi = c_1(t)\psi_1+c_2(t)\psi_2: c_1^\star c_1+c_2^\star c_2 = 1## ... so ##\psi_1## and ##\psi_2##, the eigenstates, are solutions to the time independent schrodinger equation.
... so what was your question there?
 
  • #3
Simon Bridge said:
In the representation you are talking about, it is the state vector that is time dependent... not the eigenstates.
##\psi = c_1(t)\psi_1+c_2(t)\psi_2: c_1^\star c_1+c_2^\star c_2 = 1## ... so ##\psi_1## and ##\psi_2##, the eigenstates, are solutions to the time independent schrodinger equation.
... so what was your question there?

I believe only the eigen states of energy are the stationary states and do not depend on time, so if we are measuring spin eigen states, they could be time dependent. Isn't the time independent Schrodinger equation a energy eigen value equation?
 
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  • #4
klen said:
I believe only the eigen states of energy are the stationary states and do not depend on time, so if we are measuring spin eigenstates, they could be time dependent. Isn't the time independent Schrodinger equation a energy eigenvalue equation?

It is. However, if two operators commute they will have shared eigenstates, and ##S_z## commutes with the Hamiltonian. Thus there are states that are eigenstates of both energy and spin, and both remain constant over time.
 

What is the Stern Gerlach experiment?

The Stern Gerlach experiment is a physics experiment that was first conducted in 1922 by Otto Stern and Walter Gerlach. It is used to demonstrate the quantum mechanical property of a particle's spin.

How does the Stern Gerlach experiment measure spin?

In the Stern Gerlach experiment, a beam of particles (usually silver atoms) is passed through an inhomogeneous magnetic field. The beam is then deflected in one of two directions, depending on the orientation of the particles' spin. This deflection can be measured and used to determine the particles' spin.

What is spin in quantum mechanics?

In quantum mechanics, spin is a fundamental property of particles that describes their intrinsic angular momentum. It is a quantum mechanical property, meaning it can only take certain discrete values, rather than a continuous range of values like classical angular momentum.

How is spin measured in the Stern Gerlach experiment?

In the Stern Gerlach experiment, the particles' spin is measured indirectly by observing the deflection of the beam. The direction of the deflection indicates the orientation of the particles' spin. By measuring the deflection, the spin can be determined.

Why is the Stern Gerlach experiment important?

The Stern Gerlach experiment is important because it provided evidence for the existence of spin, a fundamental property of particles. It also helped to confirm the principles of quantum mechanics and has been used to make important discoveries in the field of quantum physics.

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