# Mott-Insulator-Aided Detection of Ultra-Narrow Feshbach Resonances

### Submission summary

 As Contributors: Manfred Mark · Florian Meinert Arxiv Link: https://arxiv.org/abs/1808.05496v1 Date accepted: 2018-11-15 Date submitted: 2018-08-17 Submitted by: Mark, Manfred Submitted to: SciPost Physics Domain(s): Experimental Subject area: Quantum Physics

### Abstract

We report on the detection of extremely narrow Feshbach resonances by employing a Mott-insulating state for cesium atoms in a three-dimensional optical lattice. The Mott insulator protects the atomic ensemble from high background three-body losses in a magnetic field region where a broad Efimov resonance otherwise dominates the atom loss in bulk samples. Our technique reveals three ultra-narrow and previously unobserved Feshbach resonances in this region with widths below $\approx 10\,\mu$G, measured via Landau-Zener-type molecule formation and confirmed by theoretical predictions. For comparatively broader resonances we find a lattice-induced substructure in the respective atom-loss feature due to the interplay of tunneling and strong particle interactions. Our results provide a powerful tool to identify and characterize narrow scattering resonances, particularly in systems with complex Feshbach spectra. The observed ultra-narrow Feshbach resonances could be interesting candidates for precision measurements.

### Submission & Refereeing History

Submission 1808.05496v1 on 17 August 2018

## Reports on this Submission

### Anonymous Report 1 on 2018-9-27 Invited Report

• Cite as: Anonymous, Report on arXiv:1808.05496v1, delivered 2018-09-27, doi: 10.21468/SciPost.Report.594

### Strengths

1-great idea that brings a now toolbox to probing atom scattering;
2-new way to study scattering in correlated quantum status in lattices;
3-will lead to new ways for spectroscopy;
4-very clear presentation;

none

### Report

This is a very nice innovative paper, which will give a new impulse for studying interacting quantum matter. Most intertestingly is shows a new way of studying bound states in atom-atom scattering which are usually not accessible, and gives a clean demonstration of how to measure very narrow Feshbach resonances. The presented approach to investigate atom scattering is of interest especially for atoms with complex and overlapping Feshbach spectra like dipolar lanthanides like Er. The presented research will also lead to important input for improving the accuracy of coupled-channels calculations of molecular potentials.

### Requested changes

1- Figure 2: use same colors and symbols for the specific resonances in both graphs

• validity: top
• significance: top
• originality: high
• clarity: high
• formatting: perfect
• grammar: excellent