Enhancing quantum I/O: proven transmon qubit performance with scalable I/O over flexible integrated circuits part 1/2

Transmon quantum computers have reached a significant milestone, with many research teams now building quantum processors with over 10 qubits, and some even working towards 1.000+-qubit systems. Future steps require both higher qubit count as well as longer coherence times.  

Connecting room temperature equipment to the QPU is key for these two challenges. Scaling these interconnects requires high signal integrity, low thermal load within a small space. To that end, we present flexible planar multichannel microwave circuits (flex) with a combination of integrated resistive, and superconducting structures to link control- and read-out electronics to the qubits at milliKelvin temperatures. 

In the first part of a two-part presentation, we first introduce relevant quality metrics of the I/O chain for which it was optimized. Then we present experimental data on qubit performance comparing both flex and conventional coaxial I/O solutions. This benchmark data shows at least on-par performance between the two approaches.