Fig. 9: The exact 3-to-2 gadget.
From: Going beyond gadgets: the importance of scalability for analogue quantum simulators
The (blue) 3-local interaction between A, B, and C is replaced by a series of (blue) 2-local interactions, where the A site has been split into two sites A1 and A2. However, after this process, the 2-local interaction (red) between A and another qubit E is replaced by two 3-local interactions between E, A1, B and E, A2, B. Compare this with Fig. 8b, for which additional interactions on qubit A will remain on qubit A of the gadgetised Hamiltonian without any need for adjustment.
