7 research outputs found
Thermal and quantum depletion of superconductivity in narrow junctions created by controlled electromigration
Superconducting nanowires currently attract great interest due to their application in
single-photon detectors and quantum-computing circuits. In this context, it is of fundamental
importance to understand the detrimental fluctuations of the superconducting order
parameter as the wire width shrinks. In this paper, we use controlled electromigration to
narrow down aluminium nanoconstrictions. We demonstrate that a transition from thermally
assisted phase slips to quantum phase slips takes place when the cross section becomes less
than 150 nm2 . In the regime dominated by quantum phase slips the nanowire loses its
capacity to carry current without dissipation, even at the lowest possible temperature. We
also show that the constrictions exhibit a negative magnetoresistance at low-magnetic fields,
which can be attributed to the suppression of superconductivity in the contact leads. These
findings reveal perspectives of the proposed fabrication method for exploring various
fascinating superconducting phenomena in atomic-size contacts