In theory, should neuromorphic computers be more efficient than traditional computers when performing logic?

There is this general sentiment about neuromorphic computers that they are simply "more efficient" than von Neuman.

I’ve heard a lot of talk about neuromorphic computers in the context of machine learning.
But, is there any research into performing logic and maths in general on such computers? How would one translate arithmetic, logic and algorithms and into "instructions" for a neuromorphic computer, if there are no logic structures in the hardware itself?

It is common to draw parallels with a brain in this context, so here’s one: Brains are great at recognising faces and such, but I don’t think I can do maths faster than an Arduino (and that thing doesn’t need much energy).