Flip‐Chip Integration of the Superconducting Quantum‐Classical Circuits: Coupling Types

As quantum computing evolves from the multi‐qubit stage to large multimodularprocessors, addressability and scalability of quantum hardware will require 3D integration and packaging. The advancement of flip‐chip technology is critical to enabling progress in this area. However, various types of coupling, such as capacitive, inductive, and galvanic, still require systematic research into the principles, quantification, and loss mechanisms. In this article, different types of 3D architecture are examined using flip‐chip technology. The and superconducting resonators with qubit circuits are designed in a modular configuration consisting of two silicon substrates. This arrangement allows numerical analysis and systematic experimental investigation of capacitive, inductive, and galvanic coupling mechanisms. The transmission of short control pulses for fast qubit manipulation is demonstrated and the feasibility of quantum state transfer is theoretically explored, highlighting the potential of this approach for scalable quantum processors. Particular focus is also on the fabrication technology of superconducting indium bumps between silicon substrates.