Exploring dispersive qubit readout in the strong driving limit.*

Dispersive readout in superconducting circuits is a limiting factor in the performance of current quantum processors. Experimentally, it has been observed that increasing the intensity of the readout pulses improves the signal-to-noise ratio of the measurement up to some threshold [1,2], where non-dispersive effects and leakage to higher levels enter into play. In this work, we perform a numerical study of the dispersive measurement of superconducting qubits to find the optimal calibration point in the strong driving limit. Moreover, using QND measurement tomography [3,4], we identify the physical processes and error sources that affect the QND nature of the measurement.

[1] T. Walter, et al, Phys. Rev. Appl. 7, 054020 (2022).

[2] E. H. Chen, et al, Phys. Rev. Lett. 128, 110504 (2022).

[3] L. Pereira, et al, Phys. Rev. Lett. 129, 010402 (2022).

[4] L. Pereira, et al, arXiv:2204.10336.