Assessing risk to superconducting circuits using a high-performance, 3D time-dependent Ginzburg-Landau simulator

The development of robust superconducting circuits is critical to advance a new generation of compute technologies utilizing ultra-low-power digital logic. A fundamental challenge for the design of devices capable of performing superconducting digital logic is reliable control of undesirable magnetic flux quanta (fluxons) that form in the system below the superconducting transition temperature. One flux mitigation strategy leveraged in RQL, a proprietary superconducting logic technology, is the use of patterned arrays of holes in superconducting ground planes to sequester fluxons away from active circuitry. To assess and mitigate this risk, a high-performance 3D time-dependent Ginzburg-Landau (TDGL) simulation tool was developed and employed to quantify energy scales of complex configurations of fluxons as well as simulate magnetic field distributions in multi-ground-plane structures. The results of extensive TDGL simulation studies indicate a sublinear trend in the energy penalty for misalignment of fluxons as a function of distance. Furthermore, the resulting spatial distribution of the computed magnetic fields can be used to inform the layout of flux-sensitive superconducting circuit components.