  We present analytical and numerical simulation results for squeezing,
entanglement, and quantum discord in a dissipatively coupled coherent Ising
machine (CIM). Both analytical solutions and numerical simulation results,
which are obtained with positive-P, truncated-Wigner and truncated-Husimi
representations for the density operator, predict the presence of entanglement
and quantum discord, below and above the threshold of CIM. The entanglement
criteria and quantum discord are evaluated as a function of the dissipative
coupling strength relative to the background loss. For coupled two DOPOs, while
entanglement disappears as the background loss exceeds the Ising coupling
strength, the quantum discord remains finite even with a large linear loss. For
one-dimensional lattice of DOPOs, while entanglement disappears for DOPO pair
with large distance, quantum discord remains finite.
