Long-distance radiative coupling between quantum dots in photonic crystal dimers

TL;DR

This paper investigates how two quantum dots can interact via radiative coupling in photonic crystal dimers, revealing conditions for strong, long-distance coupling suitable for quantum entanglement in integrated nanophotonics.

Contribution

It demonstrates that effective long-distance radiative coupling between quantum dots is achievable in photonic crystal dimers, even with emitter position disorder, under strong cavity-cavity coupling conditions.

Findings

Maximized coupling at resonance with bonding or antibonding modes

Coupling strength in the meV range, nearly independent of cavity distance

Robustness against emitter position disorder

Abstract

We study the mutual interaction between two identical quantum dots coupled to the normal modes of two-site photonic crystal molecules in a planar waveguide geometry, i.e. photonic crystal dimers. We find that the radiative coupling between the two quantum emitters is maximized when they are in resonance with either the bonding or the antibonding modes of the coupled cavity system. Moreover, we find that such effective interdot coupling is sizable, in the meV range, and almost independent from the cavities distance, as long as a normal mode splitting exceeding the radiative linewidth can be established (strong cavity-cavity coupling condition). In realistic and high quality factor photonic crystal cavity devices, such distance can largely exceed the emission wavelength, which is promising for long distance entanglement generation between two qubits in an integrated nanophotonic platform. We show that these results are robust against position disorder of the two quantum emitters within their respective cavities.