Chiral Many-Body Quantum Optics in the Presence of Structured Environments

• Applicant: Dr. Beatriz Olmos Sanchez
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 452935230

An excited atom interacting with the radiation field decays by emitting a photon. This behaviour drastically changes in the case of an ensemble of atoms, as these emitters collectively couple to the radiation field. On one hand, the exchange of virtual photons induces dipole-dipole long-ranged interactions among the atoms. On the other hand, excitations in the ensemble can either decay extremely fast or remain stable over very long times due to the constructive or destructive interference of the decay channels, respectively. These collective phenomena were theoretically predicted for atoms in free space already in the 1950s. However, only rather recently several experiments have unambiguously demonstrated these effects.Even richer physics can be observed when the atoms couple collectively to photonic nanostructures, such as photonic crystals and optical nanofibers. These systems support a small number of so-called guided electromagnetic modes, through which light propagates only longitudinally along the nanostructure. Selecting appropriately the atomic positions and polarizations can open a photon decay channel into this set of modes, which enables the transport of the light with negligible losses while inducing all-to-all interactions among the atoms. These features have led to the identification of experimental platforms such as nanofibers, photonic crystals or photonic topological insulators coupled to nearby emitters, as candidate systems for the implementation of quantum information and communication protocols.In this proposal, we will study a laser-driven ensemble of atoms coupled to the radiation field in the presence of these guiding photonic structures. We will exploit the collective character of the coupling of the atoms to these structures to:- develop strategies for enhancing the coupling of the ensemble of atoms to the guided modes of the nanophotonic structures, i.e. reducing the amount of photons that are lost into free space. This will be essential to realize actual applications in quantum information and communications, such as non-reciprocal photonic devices or quantum state transport.- investigate the largely unexplored regime of strong driving, where the interplay between the driving and the all-to-all interactions will highlight a path towards the creation and analysis of strongly correlated atomic states.- develop a framework for the creation and analysis of guided photonic states, which will inform the development of steady-state sources of correlated photons and non-classical photonic states, with potential applications in quantum information and communication.A detailed study of these photonic systems will not only allow to uncover and characterise new collective many-body phenomena but will almost certainly add new capabilities to these platforms which may be exploitable in future technological applications.

• DFG Programme: Research Grants