Operational reversibility of data would be a necessary but not sufficient condition for 0-energy (isoentropic) computation. Isoentropic (i.e. one that doesn't

Operational reversibility of data would be a necessary but not sufficient condition for 0-energy (isoentropic) computation. Isoentropic (i.e. one that doesn't increase entropy) process needs, as you cite, microscopic reversibility ("local reversibility"), all the physical states of the machine itself must be reversible during the entire operation (i.e. each atom can only change state isoentropically); it's really a physical property of the computer and not a mathematical property of the computation. As I see it, this can only be achieved near 0K under very special conditions, essentially like a quantum computer (QCs also operate under this reversible regime, but not in the interest of energy saving).