Quantum group-twisted tensor products of C*-algebras

We put two C*-algebras together in a noncommutative tensor product using quantum group coactions on them and a bicharacter relating the two quantum groups that act. We describe this twisted tensor product in two equivalent ways. The first construction is based on certain pairs of representations of quantum groups which we call Heisenberg pairs because they generalise the Weyl form of the canonical commutation relations. The second construction uses covariant Hilbert space representations. We establish basic properties of the twisted tensor product and study some examples.