abstract: Motivated by applications for non-perturbative topological strings in toric Calabi-Yau manifolds, I will talk about the spectral problem for a pair of commuting modular conjugate (in the sense of Faddeev) Harper type operators with complex values of Planck's constant. The eigenvectors are expressed in terms of a special entire function on the complex plane with the Taylor expansion coefficients given in terms of specific q-orthogonal polynomials, while the eigenvalues are solutions of transcendental Bethe type equations. This is a joint work with Sergey Sergeev.