Scalable interconnection using a superconducting flux qubit

Superconductingquantum computers are rapidly reaching scales where bottlenecks to scalingarise from the practical aspects of the fabrication process. To improve quantumcomputer performance, implementation technology that guarantees the scalabilityof the number of qubits is essential. Increasing the degrees of freedom inrouting by 2.5-dimensional implementation is important for realizing circuitscalability. We report an implementation technology to overcome the scaling bottlenecksusing a reliable connection qubit with a demonstration of quantum annealing.The method comprises interconnection based on quantum annealing using asuperconducting flux qubit, precise coupling status control, and flip-chipbonding. We perform experiments and simulations with a proof-of-conceptdemonstration of qubit coupling via interconnection using a flux qubit. Thecoupling status is strictly controllable by quantum annealing. Alow-temperature flip-chip bonding technology is introduced for the2.5-dimensional interconnection. The superconducting flux qubit, formed acrosstwo different chips via bumps, is demonstrated for the first time to show astate transition like that in a conventional qubit. The quantum annealing fluxqubit and flip-chip bonding enable new interconnections between qubits. Aperspective on the possibility of applying this technology to the connectionbetween gate-type qubits is described.

文章链接：https://doi.org/10.1038/s41598-024-65086-1