We have realized a coherent Ising machine (CIM), which finds solutions to combinatorial optimization problems by simulating interacting spins using networked optical parametric oscillators (OPO). To implement flexible spin-spin interactions, we employed the measurement-feedback scheme so that all-to-all connection among 2048 DOPOs was achieved. As a result, our CIM successfully found solutions to maximum cut problems of a 2000-node complete graph with less than a ten-thousandth of a second.

This work was undertaken as a collaborative research with Japan Science and Technology Agency, National Institute of Informatics, Osaka University, University of Tokyo, and Stanford University, and supported by the ImPACT program of the Council of Science, Technology and Innovation (Cabinet Office, Government of Japan).

=> Quantum Optical State Control Research Group

Publication information

“A coherent Ising machine for 2000-node optimization problems” Science Vol. 354, Issue 6312, pp. 603-606 (2016).
“A fully-programmable 100-spin coherent Ising machine with all-to-all connections” Science Vol. 354, Issue 6312, pp. 614-617 (2016).