Interferometry based on quantum Kibble-Zurek mechanism

TL;DR

This paper introduces a quantum interferometry method based on the quantum Kibble-Zurek mechanism, demonstrating how two critical dynamics can interfere, revealing observable quantum many-body oscillations and complex dephasing effects in spin chain models.

Contribution

It proposes a novel interferometry scheme utilizing quantum Kibble-Zurek dynamics with specific quench protocols on spin chains, highlighting observable interference effects and dephasing phenomena.

Findings

Observation of quantum coherent oscillations in defect density.

Identification of interference effects from multiple critical dynamics.

Analysis of complex dephasing involving multiple length scales.

Abstract

We propose an interferometry within the framework of quantum Kibble-Zurek mechanism by exemplifying two prototypical quench protocols, namely the round-trip and quarter-turn ones, on the transverse Ising and quantum $XY$ chains. Each protocol contains two linear ramps that drive the system across quantum critical point twice. The two linear ramps arouse two respective nonadiabatic critical dynamics that are well described by the quantum Kibble-Zurek mechanism. However, in combination, the two critical dynamics can interfere with each other deeply. As an effect of the interference, the dynamical phase is exposed in the final excitation probability, which leads to a quantum coherent many-body oscillation in the density of defects with predictable characteristic period. Thus such an interference is available for direct experimental observations. In the quantum $XY$ model, we show that an interference can also arise from the interplay between two different critical dynamics derived from a critical point and a tricritical point. Furthermore, we demonstrate that the interference influences the dephasing of the excited quasiparticle modes intricately by disclosing a phenomenon of multiple length scales, diagonal and off-diagonal ones, in the defect-defect correlators. It turns out that the dephased result relies on how the diagonal and off-diagonal lengths are modulated by the controllable parameter in a quench protocol.