Breakdown of electron-pairs in the presence of an electric field of a superconducting ring

TL;DR

This paper investigates how an external electric field affects electron pairs in a superconducting ring modeled by the Hubbard Hamiltonian, revealing a transition from superconducting to metallic phase influenced by electron correlation.

Contribution

It demonstrates the field-induced breakdown of electron pairs in a superconducting ring using exact diagonalization and Crank-Nicolson methods, highlighting the role of electronic correlation.

Findings

Electron pairs break under increasing electric field strength.

The transition from superconducting to metallic phase depends on electronic correlation.

Flux-quantization confirms the phase transition.

Abstract

The quantum dynamics of quasi-one-dimensional ring with varying electron filling factor is investigated in presence of external electric field. The system is modeled within Hubbard Hamiltonian with attractive Coulomb correlation, which results in superconducting ground state when away from half-filling. The electric field is induced by applying time-dependent Aharonov-Bohm flux in the perpendicular direction. To explore the non-equilibrium phenomena arising from the field, we adopt exact diagonalization and Crank-Nicolson numerical method. With increase in electric field strength, the electron pairs, a signature of superconducting phase, start breaking and the system enters into a metallic phase. However, the strength of the electric field for this quantum phase transition depends on the electronic correlation. This phenomenon has been confirmed by flux-quantization of time-dependent current and pair correlation functions