Influence of Electromagnetic Environment on Tunneling Current through Normal Metal-Superconductor Junctions

Abstract

Based on a tunneling Hamiltonian model, the two-electron tunneling current through normal metal-superconductor junctions is studied by incorporating the influence of a dissipative electromagnetic environment with an Ohmic resistor R. We show that at low bias voltages the two-electron tunneling current displays a power-law behavior as I∝ V^4g+1, where g=e²R/π (h/2π) at zero temperature due to electromagnetic fluctuations. This suggests that suppression of the two-electron tunneling current is more remarkable compared with the usual tunneling current in normal junctions where I∝ V^g+1.