Hybrid Quantum System of a Nanofiber Mode Coupled to Two Chains of Optically Trapped Atoms

TL;DR

This paper presents a hybrid quantum system where cold atoms trapped near a nanofiber form coupled excitons and fiber polaritons, enabling potential long-range quantum communication with reduced decay rates.

Contribution

It introduces a novel hybrid system of nanofiber-coupled atomic lattices with analytically derived exponentially decaying inter-lattice coupling and observable fiber polaritons.

Findings

Exponential decay of inter-lattice coupling strength with distance.

Formation of fiber polaritons observable in optical spectra.

Reduced polariton decay rate at large wave vectors.

Abstract

A tapered optical nanofiber simultaneously used to trap and optically interface of cold atoms through evanescent fields constitutes a new and well controllable hybrid quantum system. The atoms are trapped in two parallel 1D optical lattices generated by suitable far blue and red detuned evanescent field modes very close to opposite sides of the nanofiber surface. Collective electronic excitations (excitons) of each of the optical lattices are resonantly coupled to the second lattice forming symmetric and antisymmetric common excitons. In contrast to the inverse cube dependence of the individual atomic dipole-dipole interaction, we analytically find an exponentially decaying coupling strength with distance between the lattices. The resulting symmetric (bright) excitons strongly interact with the resonant nanofiber photons to form fiber polaritons, which can be observed through linear optical spectra. For large enough wave vectors the polariton decay rate to free space is strongly reduced, which should render this system ideal for the realization of long range quantum communication between atomic ensembles.