Figure 1: Tile representation of reversible computational gates.
From: Quantum vertex model for reversible classical computing
(a,b) Elementary tiles representing the three computational gates for reversible circuits: ID (identity), SWAP and TOFFOLI. (c) construction of the Hamiltonians that encode the gate-satisfying states in the ground-state manifolds. Spins are placed on the boundary of the tiles. For the TOFFOLI gate, an ancilla spin is placed in the centre of the rectangular tile. Couplings needed in the Hamiltonians for the three different gates (tiles) are indicated by purple lines connecting two spins. The dashed line denotes the boundary of the tile.
