# Measurement of the atom-surface van der Waals interaction by transmission spectroscopy in a wedged nano-cell

## TL;DR

This paper introduces a transmission spectroscopy method in a wedged nano-cell to precisely measure atom-surface van der Waals interactions, enabling better characterization of atom-based nano-devices.

## Contribution

The study presents a novel experimental approach to measure atom-surface interactions with high precision using a wedged nano-cell and theoretical modeling.

## Key findings

- Measured van der Waals coefficient C3 for cesium in sapphire cell.
- Demonstrated high-precision determination of atom-surface interaction coefficients.
- Validated the method's effectiveness for characterizing atom-surface interactions.

## Abstract

We demonstrate a method for measuring atom-surface interactions using transmission spectroscopy of thermal vapors confined in a wedged nano-cell. The wedged shape of the cell allows complementary measurements of both the bulk atomic vapor and atoms close to surfaces experiencing strong van der Waals atom-surface interaction. These are used to tightly constrain the dipole-dipole collisional parameters of a theoretical model for transmission spectra that accounts for atom-surface interactions, cavity effects, collisions with the surface of the cell and atomic motion. We illustrate this method on a cesium vapor in a sapphire cell, find $C_3=1.3\pm0.1$\,kHz.$\mu$m$^3$ and demonstrate that even the weakest of the van der Waals atom-surface interaction coefficients - for ground-state alkali atom transitions - can be determined with a very good precision. This result paves the way towards a precise quantitative characterization of atom-surface interactions in a wide range of atom-based nano-devices.