Relation between harmonic oscillator potential and spin

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SUMMARY

The discussion centers on the energy levels of two spin-1/2 electrons in a one-dimensional harmonic oscillator potential with angular frequency ω. Given that a measurement of the z-component of spin, $$S_z$$, returns $$\hbar$$, the electrons must be in a symmetric triplet state. The ground state is ruled out due to its antisymmetric spatial wavefunction, leading to the conclusion that the next lowest energy state is either $$|\uparrow>|\uparrow>$$ or the symmetric superposition state $$\frac{1}{\sqrt{2}}(|\downarrow>|\uparrow>+|\uparrow>|\downarrow>)$$. The relevant energy equation is $$E = \hbar\omega(n + 1/2)$$, where n corresponds to the quantum number of the harmonic oscillator.

PREREQUISITES
  • Understanding of quantum mechanics, specifically spin-1/2 particles
  • Familiarity with harmonic oscillator potential and its energy levels
  • Knowledge of symmetric and antisymmetric wavefunctions
  • Proficiency in using the equation $$E = \hbar\omega(n + 1/2)$$
NEXT STEPS
  • Explore the properties of triplet and singlet states in quantum mechanics
  • Study the implications of spin measurements on energy levels in quantum systems
  • Learn about the role of symmetry in quantum mechanics and its effect on energy states
  • Investigate the mathematical formulation of harmonic oscillators in quantum mechanics
USEFUL FOR

Students and researchers in quantum mechanics, particularly those studying spin systems and harmonic oscillators, as well as educators looking for examples of quantum state interactions.

shootmeproton
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Homework Statement



The spin 1/2 electrons are placed in a one-dimensional harmonic oscillator potential of angular frequency ω. If a measurement of $$S_z$$ of the system returns $$\hbar$$. What is the smallest possible energy of the system?


Homework Equations



$$\hbar\omega(n+1/2)|n>$$

The Attempt at a Solution



By computing the total spin, we get $$\hbar$$. This indicates that the electrons are in one of the triplet state, meaning it is symmetric.

We can rule out the ground state because the ground state has antisymmetric spatial wavefunction, thus not in the triplet.

Now, one of those three triplets have the next lowest energy after ground state but I do not know which state would have the next lowest energy...

The triplets are:

$$|\uparrow>|\uparrow>$$
$$\frac{1}{\sqrt{2}}(|\downarrow>|\uparrow>+|\uparrow>|\downarrow>)$$
$$|\downarrow>|\downarrow>$$


Any suggestion as to how to find the next lowest energy level?

In addition, I do not know how to compute the energy level solely based on spin of the electrons. Is there a relevant equation that describes the relation between spin and energy level of the system?
 
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shootmeproton said:

Homework Statement



The spin 1/2 electrons are placed in a one-dimensional harmonic oscillator potential of angular frequency ω. If a measurement of $$S_z$$ of the system returns $$\hbar$$. What is the smallest possible energy of the system?

Homework Equations



$$\hbar\omega(n+1/2)|n>$$

The Attempt at a Solution



By computing the total spin, we get $$\hbar$$. This indicates that the electrons are in one of the triplet state, meaning it is symmetric.

We can rule out the ground state because the ground state has antisymmetric spatial wavefunction, thus not in the triplet.

Now, one of those three triplets have the next lowest energy after ground state but I do not know which state would have the next lowest energy...

The triplets are:

$$|\uparrow>|\uparrow>$$
$$\frac{1}{\sqrt{2}}(|\downarrow>|\uparrow>+|\uparrow>|\downarrow>)$$
$$|\downarrow>|\downarrow>$$Any suggestion as to how to find the next lowest energy level?

In addition, I do not know how to compute the energy level solely based on spin of the electrons. Is there a relevant equation that describes the relation between spin and energy level of the system?

Watch out. They say that the z \, component is measured to be ## \hbar##. They are not talking about the total spin here, but the z component. This means that both their spin must be up. Therefore their spin function is symmetric. From this what can we say about their energy?
 

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