Measurement-Induced Qubit State Mixing in Circuit QED from Up-Converted Dephasing Noise
Measurement-Induced Qubit State Mixing in Circuit QED from Up-Converted Dephasing Noise
We observe measurement-induced qubit state mixing in a transmon qubit dispersively coupled to a planar readout cavity. Our results indicate that dephasing noise at the qubit-readout detuning frequency is up-converted by readout photons to cause spurious qubit state transitions, thus limiting the nondemolition character of the readout. Furthermore, we use …