3D integration of superconducting qubits with bump bonds: Part 1

Advanced fabrication techniques focusing on eliminating lossy dielectrics and meticulously cleaning interfaces have enabled increased quantum coherence in superconducting quantum bits (qubits). However, in order to architect a large system of interconnected qubits, dense control lines must be routed in 3D while preserving qubit coherence. We report on our development of superconducting-indium-bump flip-chip technology for connecting a multi-layer signal routing carrier chip to a pristine qubit chip. We will report on process development for integrating indium into our qubit fabrication as well as the performance of this superconducting link from DC to microwave frequencies.