Richard Feynman published a lesser-known set of lectures on the subject of computation and he deals with this. The computational system he depicts is one in wh

Richard Feynman published a lesser-known set of lectures on the subject of computation and he deals with this. The computational system he depicts is one in which 'computation' occurs as a intentionally setup quantum system falls to its ground state. It might take an arbitrarily long amount of time, but the computation will occur with zero energy loss. In order to get the result more quickly you can input energy and spur along the process. He also deals with the theoretical, and some of the practical, considerations surrounding reversible computing (which he stresses as critically important for zero-energy-used computing). I've always just considered it a matter of if X bits of information enter into a system and you are only preserving Y bits of them... the others have to go somewhere. Information is as physical as anything else, even though it can take many forms. We usually end up dumping it as heat, but we could have it be vibration or RF or maybe some weird geometry morphing (on the quantum scale I mean) all the same.