Full-magnetic implementation of a classical Toffoli gate

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-spin configurations produce an effective field capable of conditionally flipping the target spin. We study what the experimental requirements are 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.