Negative-mass exciton polaritons induced by dissipative light-matter coupling in an atomically thin semiconductor

Abstract

Dispersion engineering is a powerful and versatile tool that can vary the speed of light signals and induce negative-mass effects in the dynamics of particles and quasiparticles. Here, we show that dissipative coupling between bound electron-hole pairs (excitons) and photons in an optical microcavity can lead to the formation of exciton polaritons with an inverted dispersion of the lower polariton branch and hence a negative mass. We perform direct measurements of the anomalous dispersion in atomically thin (monolayer) WS${}_2$ crystals embedded in planar microcavities and demonstrate that the propagation direction of the negative-mass polaritons is opposite to their momentum. Our study introduces a new concept of non-Hermitian dispersion engineering for exciton polaritons and opens a pathway for realising new phases of quantum matter in a solid state.

16 pages, 13 figures

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Cited by in corpus (8)

• Reconfigurable quantum fluid molecules of bound states in the continuum
• Polaritonic Quantum Matter
• 2D material exciton-polariton transport on 2D photonic crystals
• Dissipative light-matter coupling and anomalous dispersion in nonideal cavities
• Intercavity polariton slows down dynamics in strongly coupled cavities
• Waveguide QED with dissipative light-matter couplings
• Microscopic Theory of Polaron-Polariton Dispersion and Propagation
• Engineering strong coupling in ultra-compact photonic crystal/2D material platforms