Skip to Content

Quantum Mechanics 1: Operators and Eigenvalues

Explain why the kinetic energy term in the Hamiltonian is written as p22m\frac{p^2}{2m}, knowing that pp is the momentum operator and mm is the mass of the system.

Consider two quantum operators AA and BB. Determine whether [A,B]=0[A, B] = 0 or not, where [A,B][A, B] is the commutator of AA and BB.

Determine whether the kinetic energy operator and the momentum in the X direction operator commute.

Given a matrix AA and a vector xx, find an eigenvector of AA, where the eigenvalue is the factor by which the eigenvector is stretched when the matrix is applied.

Given a quantum system, such as the spin of an electron, determine the eigenstates and eigenvalues when a measurement is made on the system.

What functions are there that I can take the derivative of and get back a constant times the original function?

Prove that the Hermitian adjoint of a scalar is the complex conjugate.

Prove that the hermitian adjoint of a product of operators is calculated by switching their order and taking the individual hermitian adjoints.

Prove that the eigenvalues of any Hermitian operator must be real numbers.

Given that nn is an eigenstate of the number operator NN, show how the action of the lowering operator aa and the raising operator aa^\dagger changes the eigenvalue.

Verify whether a given function is an eigenfunction for a specified operator by calculating derivatives and checking if the function returns in the form aψa \psi.

What is the Hamiltonian operator in quantum mechanics and how is it represented in the Schrödinger equation?

Using the derived formula, determine the rate of change of position for a quantum mechanical particle, given the expression H=p22m+U(x)H = \frac{p^2}{2m} + U(x) for the Hamiltonian.

In this problem, we're dealing with a situation where the magnetic field is at some angle relative to the z-axis, but we've written the Hamiltonian in the spin up spin down basis. Part A: Obtain the matrix representation of HH in the spin up spin down basis. Part B: Find the eigenvalues and normalized eigenvectors of HH. Part C: Verify that the normalized eigenvectors of HH, denoted as E1E_1 and E2E_2, satisfy the Dirac completeness relation.