Degeneracy in Quantum Mechanics

In summary, degeneracy refers to the situation in quantum mechanics where two or more quantum states have the same energy level. This phenomenon is commonly seen in bosons, while fermions are typically non-degenerate. Degeneracy can occur when solving the Schrodinger Equation for a particular potential, resulting in multiple states with the same energy. This can be seen in the example of a particle in a 3D box, where three independent quantum states can have the same energy. Fermions can also exhibit degeneracy, but their spin must be taken into account.
  • #1
hc91
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Can anyone explain to me what Degeneracy is properly. I know its something to do with having different eigenvalues on the same energy level or something like that, but have not been able to find a good explanation in any textbooks or anywhere online. And how does something have infinite degeneracy?
 
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  • #3
When you solve the Schrodinger Equation for a particular potential, you sometimes get different states that have the same energy. For example consider a particle in a 3D box. The energy is labeled by 3 quantum numbers (nx, ny, nz). The 3 numbers are equivalent so (2 1 1), (1 2 1), and (1 1 2) are three independent quantum states that have the same energy. It is said they are degenerate. Notice that because the states are linearly independent, you can have fermions at the same energy because one can occupy each on of these states (if you include spin, then two fermions can actually occupy each one of those states, so spin doubles the number of degenerate states if it does not appear in the hamiltonian.)
 

FAQ: Degeneracy in Quantum Mechanics

1. What is degeneracy in quantum mechanics?

Degeneracy in quantum mechanics refers to the situation where multiple quantum states have the same energy level. This means that the different quantum states are indistinguishable from one another and cannot be uniquely identified by their energy levels.

2. How does degeneracy occur in quantum systems?

Degeneracy can occur in quantum systems due to symmetries in the system, such as rotational or reflection symmetries. These symmetries result in different quantum states having the same energy level, leading to degeneracy.

3. What is the significance of degeneracy in quantum mechanics?

Degeneracy plays an important role in quantum mechanics as it allows for multiple quantum states to have the same energy level, providing a greater variety of possible states for a system. It also allows for the existence of degenerate ground states, which can have important implications in certain physical phenomena.

4. How is degeneracy broken in quantum systems?

Degeneracy can be broken in quantum systems by introducing perturbations or external fields that break the symmetries present in the system. This results in the energy levels of the different quantum states becoming different and the degeneracy being lifted.

5. How is degeneracy related to the uncertainty principle?

Degeneracy in quantum mechanics is related to the uncertainty principle in that it reflects the limitations of our ability to measure and predict the exact state of a quantum system. The uncertainty principle states that the more precisely we know the energy of a particle, the less precisely we can know its position, and vice versa. Degeneracy adds another layer of uncertainty as we cannot determine which specific quantum state a particle is in if there are multiple degenerate states with the same energy level.

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