  We report, in a sequence of notes, our work on the Alibaba Cloud Quantum
Development Platform (AC-QDP). AC-QDP provides a set of tools for aiding the
development of both quantum computing algorithms and quantum processors, and is
powered by a large-scale classical simulator deployed on Alibaba Cloud. In this
note, we simulate a distance-3 logical qubit encoded in the 17-qubit surface
code using experimental noise parameters for transmon qubits in a planar
circuit QED architecture. Our simulation features crosstalk induced by
ZZ-interactions. We show that at the current-stage noise levels, crosstalk
contributes significantly to the dephasing of the logical qubit. This results
in a total phase-flip probability of $\sim 0.6\%$, about $60\%$ higher than
expected without considering crosstalk. This indicates that for the code
considered, the current noise parameters approach, but do not yet meet, the
break-even fault-tolerance regime.
