Towards a fictitious magnetic field trap for both ground and Rydberg state $^{87}$Rb atoms via the evanescent field of an optical nanofibre

TL;DR

This paper proposes a novel optical nanofibre-based trap for $^{87}$Rb atoms that minimizes dephasing in Rydberg states by combining fictitious magnetic fields and external bias fields, enabling improved quantum network platforms.

Contribution

It introduces a new trap design for ground and Rydberg states using fictitious magnetic fields and analyzes its properties for quantum network applications.

Findings

Calculated trap potentials for various guided modes and polarizations.

Determined trap depths and frequencies under different laser and magnetic field conditions.

Demonstrated how Rydberg atom size affects the ponderomotive potential.

Abstract

Cold Rydberg atoms, known for their long lifetimes and strong dipole-dipole interactions that lead to the Rydberg blockade phenomenon, are among the most promising platforms for quantum simulations, quantum computation and quantum networks. However, a major limitation to the performance of Rydberg atom-based platforms is dephasing, which can be caused by atomic motion within the trap. Here, we propose a trap for $^{87}$Rb cold atoms that confines both the electronic ground state and a Rydberg state, engineered to minimize the differential light shifts between the two states. This is achieved by combining a fictitious magnetic field induced by optical nanofibre guided light and an external bias magnetic field. We calculate trap potentials for the cases of one- and two-guided modes with quasi-linear and quasi-circular polarisations, and calculate trap depths and trap frequencies for different values of laser power and bias fields. Moreover, we discuss the impact of the quadrupole polarisability of the Rydberg atoms on the trap potential and demonstrate how the size of a Rydberg atom influences the ponderomotive potential generated by the nanofibre-guided light field. This work expands on the idea of light-induced fictitious magnetic field traps and presents a practical approach for creating quantum networks using Rydberg atoms integrated with optical nanofibres to generate 1D atom arrays.