Abstract
We experimentally investigate the collective radiative decay of a fully inverted ensemble of two-level atoms for a chiral, i.e., propagation direction-dependent light-matter coupling. Despite a fundamentally different interaction Hamiltonian which has a reduced symmetry compared to the standard Dicke case of superradiance, we do observe a superradiant burst of light. The burst occurs above a threshold number of atoms, and its peak power scales faster with the number of atoms than in the case of free-space Dicke superradiance. We measure the first-order coherence of the burst and experimentally distinguish two regimes, one dominated by the coherence induced during the excitation process and the other governed by vacuum fluctuations. Our results shed light on the collective radiative dynamics of cascaded quantum many-body systems, i.e., systems in which each quantum emitter is only driven by light radiated by emitters that are upstream in the cascade. Our findings may turn out useful for generating multiphoton Fock states as a resource for quantum technologies.
- Received 5 December 2022
- Revised 26 June 2023
- Accepted 2 January 2024
DOI:https://doi.org/10.1103/PhysRevX.14.011020
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Popular Summary
The clapping of an audience after an artistic performance often synchronizes, despite the absence of any reference or leader. Such spontaneous synchronization lies at the heart of a wide range of natural phenomena, from fireflies flashing in unison to synchronized heart cells to the synchronization of pendulum clocks. In quantum optics, many atoms can spontaneously emit light in perfect unison in the form of a short pulse, a phenomenon called superradiant burst. In all these examples, synchronization occurs because each part sees, hears, or feels the others and is seen, heard, or felt by the others. But what happens when this is not the case? In this study, we observe the synchronization of photon emission by atoms that are arranged in a chain.
In contrast to standard superradiant bursts, each atom “sees” only the atoms further up the chain. This is achieved by placing about one thousand cesium atoms next to an ultrathin glass fiber in such a way that the atoms can only emit light in one direction along the fiber. Even in this unusual setting, we observe superradiant bursts. This shows for the first time that this type of synchronization is possible even when each atom sees only those on one side of it.
Our results shed light on fundamental aspects of the collective interaction of light and matter. Moreover, our findings may contribute to the development of quantum technological applications, such as the generation of highly nonclassical states of light, which are relevant for precision measurements and quantum communication.
