Reversible Computing for Energy Efficient and Trustable Computation

entropy when information is discarded. Early physicists were confused on this point, suggesting that a minimum energy dissipation of kT ln 2 was associated with each boolean logic operation performed. Landauer [Lan86] forcefully pointed out that this result was incorrect, and that this minimum dissipation limit applied only to each bit erased. This result remained an interesting but not particularly significant fact until the recent development in our laboratory and elsewhere [YK94, KA92] of practical forms of SCRL logic, implemented in mainstream CMOS technologies, which allow the recovery of nearly all of the power normally dissipated in digital logic when the logical operations are performed reversibly. The combination of SCRL logic and reversible computing engines enables new DOD capabilities in extremely low power electronics from portable and wearable applications to extremely dense supercomputers. Current architectures discard