SQUIPT - Superconducting Quantum Interference Proximity Transistor

We present the realization and characterization of a novel-concept interferometer, the superconducting quantum interference proximity transistor (SQUIPT). Its operation relies on the modulation with the magnetic field of the density of states of a proximized metallic wire embedded in a superconducting ring. Flux sensitivities down to $\sim 10^{-5} \Phi_0$Hz$^{-1/2}$ can be achieved even for a non-optimized design, with an intrinsic dissipation ($\sim 100$ fW) which is several orders of magnitude smaller than in conventional superconducting interferometers. Our results are in agreement with the theoretical prediction of the SQUIPT behavior, and suggest that optimization of the device parameters would lead to a large enhancement of sensitivity for the detection of tiny magnetic fields. The features of this setup and their potential relevance for applications are further discussed.