Experimental study of flux noise in nanowire transmons subject to an applied magnetic field*

Flux noise is generally the dominant dephasing mechanism in transmon qubits using SQUID loops as a tunable inductive element. Continuing experimental research ambitions to elucidate the microscopic origin and mitigation of flux noise. In this work, we experimentally investigate flux noise using an unconventional knob for circuit QED: an applied in-plane magnetic field. We first present various changes introduced to our circuit QED system and setup to further extend the field compatibility of resonators and nanowire transmons beyond 70 mT and to reduce extrinsic noise. Next, we use standard coherence measurements and sensitivity analysis on and off flux sweetspots to investigate the dependence of flux noise on field applied along the axis of the two constituent nanowire junctions.