  Ising Machines (IMs) are physical systems designed to find solutions to
combinatorial optimization (CO) problems mapped onto the IM via the coupling
strengths of its binary spins. Using the intrinsic dynamics and different
annealing schemes, the IM relaxes over time to its lowest energy state, which
is the solution to the CO problem. IMs have been implemented in quantum,
optical, and electronic hardware. One promising approach uses interacting
nonlinear oscillators whose phases have been binarized through injection
locking at twice their natural frequency. Here we demonstrate such Oscillator
IMs using nano-constriction spin Hall nano-oscillator (SHNO) arrays. We show
how the SHNO arrays can be readily phase binarized and how the resulting
microwave power corresponds to well-defined global phase states. To distinguish
between degenerate states we use phase-resolved Brillouin Light Scattering
(BLS) microscopy to directly observe the individual phase of each
nano-constriction.
