New circuit method using superconducting lumped element resonator for Quantum Annealing machine*

We propose correlating all spins on a spin glass as a quantum annealer by coupling quantum bits through superconducting lumped element resonators. Unlike the conventional type coplanar wave guide resonator, the lumped element resonator does not need to consider the waveform when qubits couple to each other. It is possible to couple many qubits with in a small space. Currently D-Wave systems Inc. released the world’s first commercial quantum annealing machine. However, there are a lot of challenges yet to be solved to fulfill the dream of a quantum annealing machine which is useful for human society. One of them is circuit scaling. It is necessary to increase the number of qubits and their coupling for mapping practical problem. It can be greatly improved with the circuit that consist of our lumped element resonator with a long edge coupled line. We use Al flux qubits with long quantum coherence time and Nb lumped element resonators. This experiment suggests that the new type of lumped element resonator can strongly couple to many qubits with in a small space for quantum annealing machine.