Table 2 Equivalent energy function for modeling higher order interactions among Ising spins. The second harmonic signal included as a part of the dynamics (not shown here) helps force \(\upphi\) to \(\{0,\uppi \}\).

From: Designing Ising machines with higher order spin interactions and their application in solving combinatorial optimization

Order

Ising interaction

Equivalent formulation for constructing dynamical system

2

\({s}_{i}{s}_{j}\)

\(\mathrm{cos}\left({\phi }_{i}-{\phi }_{j}\right)\)

3

\({s}_{i}{s}_{j}{s}_{k}\)

\(\mathrm{cos}\left({\phi }_{i}-{\phi }_{j}+{\phi }_{k}\right)\)

4

\({s}_{i}{s}_{j}{s}_{k}{s}_{l}\)

\(\mathrm{cos}\left({\phi }_{i}-{\phi }_{j}+{\phi }_{k}-{\phi }_{l}\right)\)

5

\({s}_{i}{s}_{j}{s}_{k}{s}_{l}{s}_{m}\)

\(\mathrm{cos}\left({\phi }_{i}-{\phi }_{j}+{\phi }_{k}-{\phi }_{l}+{\phi }_{m}\right)\)

6

\({s}_{i}{s}_{j}{s}_{k}{s}_{l}{s}_{m}{s}_{n}\)

\(\mathrm{cos}\left({\phi }_{i}-{\phi }_{j}+{\phi }_{k}-{\phi }_{l}+{\phi }_{m}-{\phi }_{n}\right)\)