Simulation of an asymmetric lineshape of a resonant dip observed in a switching-current measurement of a superconducting flux qubit

We performed a simulation of the switching current of a DC superconducting quantum interference device (SQUID) magnetometer that reads out the state of a superconducting flux quantum bit (qubit). Three configurations for coupling the SQUID and qubit were considered. The asymmetric lineshape of a resonant dip observed in a switching-current measurement under continuous microwaves was reproduced by the simulation taking into account the effect of the current in the SQUID arms. The flux shift due to the SQUID current was also calculated.