Measurement of the Charge dependance of readout induced transition in transmons : Experiment

Improving qubit readout is essential to reach fault-tolerant quantum computation with the cQED architecture.

However, this is made difficult by the degradation of the readout fidelity observed at small to moderate measurement drive amplitude.

In part 1 of this talk, we measure that the strength of readout demolition of the qubit state depends on the offset charge even for qubits well within the Transmon regime.

This is demonstrated by performing quantum jump experiments on Transmons at varying offset charge,

readout amplitude and flux offset,revealing many transitions between the qubit and the readout cavity.

Additionally, we perform fidelity measurement that show order of magnitude variation of the critical photon number with charge offset.

These findings are consistent with theoretical models in which the readout photons act as a Floquet drive on the qubit.