  The Toffoli gate is the essential ingredient for reversible computing, an
energy efficient classical computational paradigm that evades the energy
dissipation resulting from Landauer's principle. In this paper we analyze
different setups to realize a magnetic implementation of the Toffoli gate using
three interacting classical spins, each one embodying one of the three bits
needed for the Toffoli gate. In our scheme, different control-spins
configurations produce an effective field capable of conditionally flipping the
target spin. We study what are the experimental requirements for the
realization of our scheme, focusing on the degree of local control, the ability
to dynamically switch the spin-spin interactions, and the required single-spin
anisotropies to make the classical spin stable, showing that these are
compatible with current technology.
