  In superconductivity, electrons exhibit unique macroscopic collective quantum
behavior that is the key for many modern quantum technologies. This electron
behavior stems vastly from coupling to a correlated motion of atoms in the
material, as well as from synchronized directional movement that screens
external magnetic fields perfectly. Hence, the inter-atomic distance and
material geometry are expected to affect fundamental superconductive
characteristics. These parameters are tunable with strain, but strain
application is hindered by the rigidity of superconductors, which in turn
increases at device-relevant temperatures. Here, we present flexible, foldable
and transferable superconducting materials, and functional quantum
nanostructures by depositing superconductive amorphous-alloy films on a
flexible adhesive tape. Specifically, flexible superconducting films, nanowires
and quantum interference devices (SQUIDs) were fabricated and characterized
under variable magnetic-field, current, temperature and flexure conditions. The
SQUID interference periodicity, which represents a single flux quantum,
exhibits unexpected tunability with folding curvature. This tunability raises a
need for a relook at the fundamentals of superconductivity, mainly with respect
to effects of geometry, magnetic-field inhomogeneity and strain. Our work paves
the way for novel magnetic devices and quantum-technology platforms with local
tunability.
