Microwave drives play a central role in the control of superconducting quantum circuits, enabling qubit gates, readout, and parametric interactions. As the drive frequencies are typically an order of magnitude smaller than (twice) the superconducting gap, it is generally assumed that such drives do not disturb the BCS ground state. However, sufficiently strong drives can activate multiphoton pair-breaking processes that generate quasiparticles (QPs) and result in qubit errors. In this work, we present a theoretical framework for calculating the rates of multiphoton-assisted pair-breaking transitions induced by charge- or flux-coupled microwave drives. Through illustrative examples, we show that photon-assisted QP generation may affect novel high-frequency dispersive readout architectures, as well as Floquet-engineered superconducting circuits operating under strong driving.
@article{arxiv.2505.00773,
title = {Theory of quasiparticle generation by microwave drives in superconducting qubits},
author = {Shoumik Chowdhury and Max Hays and Shantanu R. Jha and Kyle Serniak and Terry P. Orlando and Jeffrey A. Grover and William D. Oliver},
journal= {arXiv preprint arXiv:2505.00773},
year = {2026}
}
Comments
Updated to the final version published as an Editors' Suggestion in Physical Review Applied. Minor edits to the text and also includes a new supplementary note deriving the Josephson Hamiltonian of a superconducting qubit directly from BCS theory