One of the alternate approaches to gate level quantum computers is the Coherent Ising Machine (CIM). These are also sometimes called Quantum Neural Networks. A Coherent Ising Machine is similar to the D-Wave quantum annealer in that it is designed to solve combinatorial optimization problems, but it is different because it uses optical fiber loops, optical parametric oscillators, and other devices rather than superconducting circuits to find the ground state of an Ising Hamiltonian. Because the machine takes advantage of quantum superposition, it could potentially solve such problems much more efficiently than a classical computers. For additional details on Coherent Ising Machines, you can view an article here published in Nature magazine. We had also published an article about NTT’s earlier Quantum Neural Network machine that you can find here.
The project is expected to last 4 and a half years with Caltech developing an on-chip 100 Ghz pumped pump laser source and NTT developing an on-chip optical parametric amplifier. Although NTT has not stated the exact number of qubits this device could support, they had previously stated a goal of reaching 100,000 or more qubits with all-to-all connectivity. If it can be implemented, such a machine would have great power in solving difficult optimization problems.
For additional information on this collaboration, you can view a new release from NTT Research on their website here.
January 26, 2021