Hong-Ou-Mandel Interference between Two Deterministic Collective Excitations in an Atomic Ensemble

TL;DR

This paper demonstrates Hong-Ou-Mandel interference between two deterministic collective excitations in an atomic ensemble, showcasing entanglement and enhanced magnetic field sensitivity, advancing quantum information processing with atomic ensembles.

Contribution

It introduces a method to generate and interfere two distinct collective excitations in an atomic ensemble, enabling entanglement and quantum sensing applications.

Findings

Achieved a photon coincidence visibility of 0.89(6).

Demonstrated entangled NOON state of atomic excitations.

Showed two times enhanced magnetic field sensitivity.

Abstract

We demonstrate deterministic generation of two distinct collective excitations in one atomic ensemble, and we realize the Hong-Ou-Mandel interference between them. Using Rydberg blockade we create single collective excitations in two different Zeeman levels, and we use stimulated Raman transitions to perform a beam-splitter operation between the excited atomic modes. By converting the atomic excitations into photons, the two-excitation interference is measured by photon coincidence detection with a visibility of 0.89(6). The Hong-Ou-Mandel interference witnesses an entangled NOON state of the collective atomic excitations, and we demonstrate its two times enhanced sensitivity to a magnetic field compared with a single excitation. Our work implements a minimal instance of Boson sampling and paves the way for further multi-mode and multi-excitation studies with collective excitations of atomic ensembles.