Effects of higher-order Casimir-Polder interactions on Rydberg atom spectroscopy

TL;DR

This paper investigates how higher-order multipole interactions, beyond the dipole approximation, influence Casimir-Polder energy shifts of Rydberg atoms near surfaces, with implications for quantum technologies.

Contribution

It introduces calculations of quadrupole and octupole contributions to Casimir-Polder interactions for Rydberg atoms near dielectric surfaces, extending the understanding of atom-surface forces in extreme near-field regimes.

Findings

Higher-order multipole effects significantly alter energy shifts.

Implications for Rydberg atom-based quantum devices.

Enhanced understanding of atom-surface interactions at nanoscales.

Abstract

In the extreme near-field, when the spatial extension of the atomic wavefunction is no longer negligible compared to the atom-surface distance, the dipole approximation is no longer sufficient to describe Casimir-Polder interactions. Here we calculate the higher-order, quadrupole and octupole, contributions to Casimir-Polder energy shifts of Rydberg atoms close to a dielectric surface. We subsequently investigate the effects of these higher-order terms in thin-cell and selective reflection spectroscopy. Beyond its fundamental interest, this new regime of extremely small atom surface separations is relevant for quantum technology applications with Rydberg or surface-bound atoms interfacing with photonic platforms.