Abstract: Single photon coherent Ising machine
Speaker: Yoshihisa Yamamoto
In this talk we will review the recent progress in coherent Ising machines (CIM). The CIM is an optical parametric oscillator (OPO) network based special purpose computer for Ising model and related optimization problems. The Ising cost function is mapped to the OPO network loss landscape by dissipative coupling rather than the energy landscape by Hamiltonian coupling, which allows an upward search by gain in contrast to a standard downward search by cooling. We will discuss a new operation mode of CIM with extremely weak excitation and nonlinear measurement feedback. To our surprise, the product of time-to-solution and energy-to-solution becomes minimum and the sampling efficiency of optimum and sub-optimum solutions is maximum at an extremely weak excitation level of one (average) photon per site.