Fig. 5: Minimizing residual drive asymmetry in the SQUID via fine-tuning the circuit geometry.
From: High-fidelity parametric beamsplitting with a parity-protected converter
a The SQUID device in the buffer cavity package driven by an oscillating B-field. The cylindrical geometry of the buffer cavity (outer wall radius greater than the inner wall) dictates that the B-field has a non-uniform distribution along the radial direction (from left to right). The dashed lines with capacitor symbol represents the capacitance between the antenna pads of the SQUID and the wall of the package. b The lumped-element circuit model of the SQUID device, taking into account the geometry of SQUID and the spatial distribution of the B field. c HFSS simulation of the quality factor of the common mode (red) and drive asymmetry (blue, defined in Eq. (21)) as functions of the top pad displacement from center to right, δ. As a result of introducing this asymmetry in the device geometry, the optimization of the drive asymmetry and the quality factor are simultaneously achieved at δ ≈ 350 μm.
