1. The problem statement, all variables and given/known data A two-state system has Hamiltonian [itex]\sum |i\right\rangle hi \left\langle i| + Δ (| 1 \right\rangle \left\langle 2| + |2 \right\rangle \left\langle 1 |)[/itex] Where, [itex]\left\langle i | j \right\rangle = \deltaij[/itex], [itex]hi[/itex], and Δ are real. Compute the energy spectrum of this Hamiltonian. 2. Relevant equations N/A 3. The attempt at a solution What is this question asking me to do? What is meant by "energy spectrum"? Also; tried cleaning up the tex but something's not right and I can't seem to tell what (other than I'm on a different computer than I normally use).