Multipath interference from large trapped ion chains

TL;DR

This paper demonstrates controlled optical interference from large chains of trapped ions, showing preserved coherence and phase sensitivity, paving the way for advanced quantum optics experiments involving many emitters.

Contribution

It reports the first observation of scalable multipath interference from up to 53 trapped ions with maintained coherence and enhanced phase sensitivity.

Findings

Interference observed from chains of up to 53 ions

Coherence preserved across all measured chain sizes

Nearly optimal phase sensitivity enhancement

Abstract

The demonstration of optical multipath interference from a large number of quantum emitters is essential for the realization of many paradigmatic experiments in quantum optics. However, such interference remains still unexplored as it crucially depends on the sub-wavelength positioning accuracy and stability of all emitters. We present the observation of controlled interference of light scattered from strings of up to 53~trapped ions. The light scattered from ions localized in a harmonic trapping potential is collected along the ion crystal symmetry axis, which guarantees the spatial indistinguishability and allows for an efficient scaling of the contributing ion number. We achieve the preservation of the coherence of scattered light observable for all the measured string sizes and nearly-optimal enhancement of phase sensitivity. The presented results will enable realization and control of directional photon emission, direct detection of enhanced quadrature squeezing of atomic resonance fluorescence, or optical generation of genuine multi-partite entanglement of atoms.