Two-level Hamiltonian of a superconducting quantum point contact

TL;DR

This paper derives a two-level Hamiltonian for a superconducting quantum point contact, capturing the coupling between the superconducting phase dynamics and subgap state transitions.

Contribution

It provides a novel derivation of the two-level Hamiltonian explicitly accounting for phase and subgap state interactions.

Findings

Explicit form of the two-level Hamiltonian derived

Coupling between phase dynamics and subgap states characterized

Framework for analyzing quantum behavior in superconducting contacts

Abstract

In a superconducting quantum point contact, dynamics of the superconducting phase is coupled to the transitions between the subgap states. We compute this coupling and derive the two-level Hamiltonian of the contact.