Reflectionless analytic difference operators III. Hilbert space aspects
  In the previous two parts of this series of papers, we introduced and studied a large class of analytic difference operators admitting reflectionless eigenfunctions, focusing on algebraic and function-theoretic features in the first part, and on connections with solitons in the second one. In this third part we study our difference operators from a quantum mechanical viewpoint. We show in particular that for an arbitrary difference operator $A$ from a certain subclass, the reflectionless $A$-eigenfunctions can be used to construct an unbounded self-adjoint reflectionless operator $\hat{A}$ on $L^2({\mathbb R},dx$ whose action on a suitable core coincides with that of $A$. 
S. N. M. Ruijsenaars