Title: A discussion about LNG Experiment: Irreversible or Reversible Generation of the OR Logic Gate?,
Abstract: In a recent paper M. Lopez-Suarez, I. Neri, and L. Gammaitoni (LNG) present a
concrete realization of the Boolean OR irreversible gate, but contrary to the
standard Landauer principle, with an arbitrary small dissipation of energy. A
Popperian good falsification! In this paper we discuss a theoretical
description of the LNG device which is indeed a 3in/3out self--reversible
realization of the involved OR gate, satisfying in this way the Landauer
principle of no dispersion of energy, contrary to the LNG conclusions. The
different point of view is due to a different interpretation of the two outputs
corresponding to the inputs 10 and 01, which are considered by LNG
indistinguishable so producing a non reversible realization of the standard
2in/1out gate. On the contrary, always considering these two outputs
indistinguishable, by a suitable normalization function of the cantilever
angles, the experimental results obtained by the LNG device coincide with the
OR connective obtained from the third output of the self-reversible 3in/3out CL
gate by the Inputs-Ancilla->Garbage-Output procedure. Thus, by the
self-reversibility this realization is without dissipation of energy according
to the Landauer principle. Furthermore, using the self-reversible Toffoli gate
it is possible to obtain from the LNG device the realization of the connective
AND adopting another normalization function on the cantilever angles. Finally,
by other suitable normalization procedures on cantilever angles it is possible
to obtain also the other logic NOR and NAND connectives, and in a more
sophisticated way the XOR and NXOR connectives in a self-reversible way. All
this leads to introduce a universal logic machine consisting of the LNG device
plus a memory containing all the necessary angle normalization functions to
produce in a self-reversible way, by choosing one of these latter, the logic
connectives now listed.