A complex periodic QES potential and exceptional points

B. Bagchi, C. Quesne, R. Roychoudhury

We show that the complex $\mathcal{P}\mathcal{T}$-symmetric periodic potential $V(x)=-(\mathrm{i}\xi \sin 2x+N{)}^2$, where $\xi$ is real and $N$ is a positive integer, is quasi-exactly solvable. For…