The large physical size of superconducting qubits and their associated on-chip control structures presents a practical challenge towards building a large-scale quantum computer. In particular, transmons require a high-quality-factor shunting capacitance that is typically achieved by using a large coplanar capacitor. Other components, such as superconducting microwave resonators used for qubit state readout, are typically constructed from coplanar waveguides which are millimeters in length. Here we use compact superconducting through-silicon vias to realize lumped element capacitors in both qubits and readout resonators to significantly reduce the on-chip footprint of both of these circuit elements. We measure two types of devices to show that TSVs are of sufficient quality to be used as capacitive circuit elements and provide a significant reductions in size over existing approaches.
@article{arxiv.2308.00834,
title = {Characterization of superconducting through-silicon vias as capacitive elements in quantum circuits},
author = {Thomas M. Hazard and Wayne Woods and Danna Rosenberg and Rabi Das and Cyrus F. Hirjibehedin and David K. Kim and Jeffery Knecht and Justin Mallek and Alexander Melville and Bethany M. Niedzielski and Kyle Serniak and Katrina M. Sliwa and Donna Ruth-Yost and Jonilyn L. Yoder and William D. Oliver and Mollie E. Schwartz},
journal= {arXiv preprint arXiv:2308.00834},
year = {2023}
}