Microscopy of a scalable superatom

TL;DR

This paper demonstrates the creation and control of scalable superatoms using Rydberg atoms in an optical lattice, confirming their collective quantum properties and exploring their coherence limits for quantum technology applications.

Contribution

It introduces a method to prepare superatoms with two orders of magnitude scalability and microscopically confirms their collective quantum behavior.

Findings

Superatoms exhibit characteristic square root scaling of optical coupling.

Entanglement is verified in the prepared superatom states.

Coherent manipulation of superatoms is demonstrated.

Abstract

Strong interactions can amplify quantum effects such that they become important on macroscopic scales. Controlling these coherently on a single particle level is essential for the tailored preparation of strongly correlated quantum systems and opens up new prospects for quantum technologies. Rydberg atoms offer such strong interactions which lead to extreme nonlinearities in laser coupled atomic ensembles. As a result, multiple excitation of a Micrometer sized cloud can be blocked while the light-matter coupling becomes collectively enhanced. The resulting two-level system, often called "superatom", is a valuable resource for quantum information, providing a collective Qubit. Here we report on the preparation of two orders of magnitude scalable superatoms utilizing the large interaction strength provided by Rydberg atoms combined with precise control of an ensemble of ultracold atoms in an optical lattice. The latter is achieved with sub shot noise precision by local manipulation of a two-dimensional Mott insulator. We microscopically confirm the superatom picture by in-situ detection of the Rydberg excitations and observe the characteristic square root scaling of the optical coupling with the number of atoms. Furthermore, we verify the presence of entanglement in the prepared states and demonstrate the coherent manipulation of the superatom. Finally, we investigate the breakdown of the superatom picture when two Rydberg excitations are present in the system, which leads to dephasing and a loss of coherence.