Integrable discretisations of the noncommutative NLS equation

Abstract: We show how to derive noncommutative versions of integrable partial difference equations using Darboux transformations. As an illustrative example, we use the nonlinear Schr\"odinger (NLS) system. We derive a noncommutative nonlinear Schr\"odinger equation and we construct its integrable discretisations via the compatibility condition of Darboux transformations around the square. In particular, we construct a noncommutative Adler--Yamilov type system and a noncommutative discrete Toda equation. For the noncommutative Adler--Yamilov type system we construct B\"acklund transformations.