where μ {\displaystyle \mu } is the magnitude of the particle's magnetic moment and σ {\displaystyle {\boldsymbol {\sigma }}} is the vector of Pauli matrices. Solving the time dependent Schrödinger equation H ψ = i ℏ ∂ t ψ {\displaystyle H\psi =i\hbar \partial _{t}\psi } yields