Coherent Electron Transport in a Non-single-connected Normal Metal-Insulator-Superconductor Heterostructure

In this experimental study we investigated the electron transport properties of non-equilibrium quasiparticles injected into superconducting aluminum at extremely low temperatures. The study deals with hybrid nanostructures represented by a T-shaped metal electrode (copper), an insulating tunneling layer (aluminum oxide), and a superconducting fork (aluminum). These nanostructures serve as the solid-state analogue of a two-slit optical interferometer. By imposing a constant bias voltage close to the superconducting energy gap, we observed the non-uniform dependence of the tunneling current on perpendicular magnetic field. This phenomenon is believed to originate from the coherent component of the quasiparticle transport. Our findings provide valuable insights into the behavior of quasiparticles in superconducting materials and may be useful for operation of various nanoelectronic devices containing interfaces with a superconductor.