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arXiv · 2405.20382

Dipole-dipole interactions mediated by a photonic flat band

Enrico Di Benedetto·Alejandro Gonzalez-Tudela·Francesco Ciccarello
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Abstract

Flat bands (FBs) are energy bands with zero group velocity, which in electronic systems were shown to favor strongly correlated phenomena. Indeed, a FB can be spanned with a basis of strictly localized states, the so called "compact localized states" (CLSs), which are yet generally non-orthogonal. Here, we study emergent dipole-dipole interactions between emitters dispersively coupled to the photonic analogue of a FB, a setup within reach in state-of the-art experimental platforms. We show that the strength of such photon-mediated interactions decays exponentially with distance with a characteristic localization length which, unlike typical behaviours with standard bands, saturates to a finite value as the emitter's energy approaches the FB. Remarkably, we find that the localization length grows with the overlap between CLSs according to an analytically-derived universal scaling law valid for a large class of FBs both in 1D and 2D. Using giant atoms (non-local atom-field coupling) allows to tailor interaction potentials having the same shape of a CLS or a superposition of a few of these.

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Enrico Di Benedetto, Alejandro Gonzalez-Tudela, Francesco Ciccarello. 2024-05-30. Dipole-dipole interactions mediated by a photonic flat band. https://doi.org/10.22331/q-2025-03-25-1671

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