Cooper pair tunneling in superconducting nanowires
R_QPS: — Ω
In a superconducting nanowire, quantum fluctuations allow the phase of the order parameter to slip by 2π
(a quantum phase slip, QPS). Unlike thermally activated phase slips (TAPS), QPS occurs at T=0 by tunneling.
The QPS amplitude E_S ∝ exp(-S_core/ℏ) where S_core scales with wire cross-section and length.
The I-V characteristic becomes ohmic (V = R_QPS·I) below a critical current — the wire is resistive even at zero temperature.
This is the electromagnetic dual of the Josephson junction: charge ↔ flux, V ↔ I.