Fiber-optic quantum interface with an array of more than 100 individually addressable atoms on an optical nanofiber

TL;DR

This paper demonstrates a scalable quantum interface between guided photons in a nanofiber and an array of over 150 individually addressable cesium atoms, enabling advanced quantum networking and computing applications.

Contribution

It introduces a novel platform integrating a nanofiber with a large, addressable atomic array, achieving long trap lifetimes and individual atom control without active cooling.

Findings

Successfully trapped an average of 155 atoms in a 1D array on a nanofiber.

Achieved strong photon antibunching with $g^{(2)}(0) \\approx 0.26$.

Trap lifetimes up to 460 ms at 670 nm atom-surface distance.

Abstract

Integrating the scalability of individually addressable arrays of optical-tweezer-trapped single atoms with the efficient light-matter interface provided by nanophotonic waveguides has been a long-standing challenge in quantum technologies based on atoms and photons. Here we realize a quantum interface between photons guided in an optical nanofiber with a diameter of 310 nm and an array of on average 155 individually addressable atoms. Using a spatial light modulator and an objective lens with NA = 0.45, single cesium atoms are trapped in a one-dimensional array of 200 optical tweezer spots with micrometer-scale trap sizes on the nanofiber. Individual atoms are addressed by spatially scanning an excitation laser beam, focused to a spot size comparable to that of the traps through the same objective lens, along the nanofiber. We confirm the single-atom nature of the individual trapping sites through photon-correlation measurements of the guided fluorescence, observing strong photon antibunching with $g^{(2)}(0) \approx 0.26$. We measure trap lifetimes of a few hundred milliseconds, with a maximum value of 460 ms, at an atom-surface separation of 670 nm without active cooling, representing an order-of-magnitude improvement over previous nanofiber traps. This platform opens a new regime for atom-photon interfaces, paving the way for scalable distributed quantum computing and quantum networks, as well as for the exploration of collective radiative effects in waveguide QED with individually addressable atoms.