Scaling up superconducting quantum circuits with tileable qubit architecture

Coherent control of a superconducting quantum device, called a Cooper-pair box, was first demonstrated more than twenty years ago, triggering worldwide research on superconducting quantum bits (qubits). Consecutive efforts to improve design, materials, qubit coherence, and control fidelity since then have led to a recent dramatic increase in the number of available qubits. One of the key challenges for scalable qubit architecture is how to deliver microwave signals to the individual qubits that are just a few hundred microns apart in a two-dimensional chip. To address this issue, we adopt a tileable square-lattice qubit architecture with the coaxial cables addressing the backside of the chip from the vertical direction. In this talk, I will discuss the chip design, three-dimensional integrated wiring and performance of integrated chips of superconducting quantum computers being developed at RIKEN Center for Quantum Computing.