Is the ISW Hamiltonian Diagonal in the Energy Basis?

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SUMMARY

The discussion centers on determining the matrix elements of the Hamiltonian for the Infinite Square Well (ISW) in the energy basis. It is established that the Hamiltonian is indeed diagonal in this basis, as the matrix elements correspond to eigenvalues of the Hamiltonian operator acting on energy-basis kets. The key equations involved include the Hamiltonian expression \( H = \frac{p^2}{2m} + V \) and the time evolution equation \( \frac{d}{dt}\langle Q \rangle = \frac{i}{\hbar} \langle[\hat H, \hat Q] \rangle + \langle \frac{\partial \hat Q}{\partial t} \rangle.

PREREQUISITES
  • Understanding of Quantum Mechanics principles, particularly Hamiltonians.
  • Familiarity with the concept of matrix elements and eigenvalues.
  • Knowledge of the Infinite Square Well (ISW) model.
  • Proficiency in linear algebra, specifically matrix representation of operators.
NEXT STEPS
  • Study the derivation of the Hamiltonian for the Infinite Square Well.
  • Learn about the properties of eigenvalues and eigenvectors in quantum mechanics.
  • Explore the implications of the time evolution equation in quantum systems.
  • Investigate the relationship between operators and their matrix representations in different bases.
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Students and professionals in quantum mechanics, particularly those focusing on quantum systems, Hamiltonians, and linear algebra applications in physics.

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Homework Statement


Find the matrix elements of the Hamiltonian in the energy basis for the ISW. Is it
diagonal? Do you expect it to be diagonal?

Homework Equations



H=\frac{p^2}{2m}+V

\frac{d}{dt}\langle Q \rangle = \frac{i}{\hbar} \langle[\hat H, \hat Q] \rangle + \langle \frac{\partial \hat Q}{\partial t} \rangle


The Attempt at a Solution



How should I convert H into matrix?
 
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I assume by ISW you mean "infinite square well". Anyway, you're not asked to convert H into a matrix. You are asked to find its matrix elements. Some things: 1) Matrix elements are indexed scalars. 2) "Matrix elements" carries the connotation of "eigenvalues". 3) What happens when the Hamiltonian operator "hits" an energy-basis vector/ket? 4) What is the dual of this equation? Does that get the gears working?
 
Thanks bjnartown, I searched and found this. I already had the correct math down, but your explanation is wonderful and I really learned a lot from it. I seriously created an account to tell you that, lol.
 

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