  Macroscopic phase coherence in superconductors enables quantum interference
and phase manipulation at realistic device length scales. Numerous
superconducting electronic devices are based on the modulation of the
supercurrent in superconducting loops. While the overall behavior of symmetric
superconducting loops have been studied, the effects of asymmetries in such
devices remain under-explored and poorly understood. Here we report on an
experimental and theoretical study of the flux modulation of the persistent
current in a doubly-connected asymmetric aluminum nanowire loop. A model
considering the length and electronic cross-section asymmetries in the loop
provides a quantitative account of the observations. Comparison with
experiments give essential parameters such as persistent and critical currents
as well as the amount of asymmetry which can provide feedback into the design
of superconducting quantum devices.
