Landau-Zener-Stueckelberg physics with a singular continuum of states

TL;DR

This paper investigates the quantum dynamics of a discrete energy level coupled to a singular continuum, revealing effects like bound states and oscillations that impact mesoscopic superconducting device performance.

Contribution

It introduces a model for a discrete level interacting with a singular continuum and analyzes the resulting quantum coherence phenomena.

Findings

Formation of bound states due to quantum repulsion

Suppression of decay into the continuum

Presence of Stueckelberg oscillations

Abstract

This work addresses the dynamical quantum problem of a driven discrete energy level coupled to a semi-infinite continuum whose density of states has a square-root-type singularity, such as states of a free particle in one dimension or quasiparticle states in a BCS superconductor. The system dynamics is strongly affected by the quantum-mechanical repulsion between the discrete level and the singularity, which gives rise to a bound state, suppresses the decay into the continuum, and can produce Stueckelberg oscillations. This quantum coherence effect may limit the performance of mesoscopic superconducting devices, such as quantum electron turnstile.