Spin-gap spectroscopy in a bosonic flux ladder

TL;DR

This paper explores the phase transition and spin gap in a bosonic flux ladder system using simulations, proposing a method for experimental detection through density imbalance modulation.

Contribution

It introduces a novel spectroscopic technique to measure the spin gap and characterizes phase transitions in bosonic flux ladders.

Findings

Response to density imbalance modulation differs between phases

Proposes a practical method for many-body spectroscopy

Provides simulation-based insights into phase behavior

Abstract

Ultracold bosonic atoms trapped in a two-leg ladder pierced by a magnetic field provide a minimal and quasi-one-dimensional instance to study the interplay between orbital magnetism and interactions. Using time-dependent matrix-product-states simulations, we investigate the properties of the so-called "Meissner" and "vortex" phases which appear in such system, focusing on experimentally accessible observables. We discuss how to experimentally monitor the phase transition, and show that the response to a modulation of the density imbalance between the two legs of the ladder is qualitatively different in the two phases. We argue that this technique can be used as a tool for many-body spectroscopy, allowing to quantitatively measure the spin gap in the Meissner phase. We finally discuss its experimental implementation