Unconditional reset of a qubit readout resonator using multichannel driving

Rapid measurement is important for many quantum computing applications, such as quantum error-correction codes. We demonstrate a method for reducing the waiting time between successive measurements in a circuit QED system by actively depleting photons from a readout resonator after a measurement. The resonator ring-down time is reduced without feedback, independent of the measurement outcome. We achieve this by applying a readout tone near the resonator resonance frequency simultaneously to both the resonator and the qubit, which realizes an effectively longitudinal interaction between them [1, 2]. We present results from numerical simulations and from experiments on a typical circuit QED system.

[1] J. Ikonen, et al, Phys. Rev. Lett. 122, 080503 (2019)
[2] S. Touzard, et al, Phys. Rev. Lett. 122, 080502 (2019)