Anisotropic quantum emitter interactions in two-dimensional photonic-crystal baths

TL;DR

This paper demonstrates how to convert anisotropic dissipation of quantum emitters in 2D photonic crystals into tunable coherent interactions by breaking lattice degeneracy, enabling advanced quantum control and entanglement protocols.

Contribution

It introduces a method to achieve tunable coherent dipole-dipole interactions from anisotropic dissipation using superlattice geometries in 2D photonic crystals.

Findings

Interactions originate from qubit-photon bound states with anisotropic decay

Superlattice parameters allow tuning of interaction range and strength

Exact calculations identify regimes where Markovian dynamics applies

Abstract

Quantum emitters interacting with two-dimensional photonic-crystal baths experience strong and anisotropic collective dissipation when they are spectrally tuned to 2D Van-Hove singularities. In this work, we show how to turn this dissipation into coherent dipole-dipole interactions with tuneable range by breaking the lattice degeneracy at the Van-Hove point with a superlattice geometry. Using a coupled-mode description, we show that the origin of these interactions stems from the emergence of a qubit-photon bound state which inherits the anisotropic properties of the original dissipation, and whose spatial decay can be tuned via the superlattice parameters or the detuning of the optical transition respect to the band-edges. Within that picture, we also calculate the emitter induced dynamics in an exact manner, bounding the parameter regimes where the dynamics lies within a Markovian description. As an application, we develop a four-qubit entanglement protocol exploiting the shape of the interactions. Finally, we provide a proof-of-principle example of a photonic crystal where such interactions can be obtained.