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Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
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Intrinsically chiral exciton polaritons in an atomically-thin semiconductor
M J Wurdack1,2,3,4,5, I Iorsh6, S Vavreckova7,8,9
1Institute of Solid State Physics, Friedrich Schiller University Jena, Jena, Germany. mwurdack@stanford.edu.
Nature Communications
|March 24, 2026
Summary
Chiral bound states in the continuum (BICs) enable strong coupling between light and spin-polarized excitons in 2D semiconductors. This creates valley-selective exciton polaritons with enhanced circular polarization for quantum optics applications.
Area of Science:
- Quantum optics and nanophotonics
- Condensed matter physics
- Materials science
Background:
- Photonic bound states in the continuum (BICs) confine light for enhanced light-matter interactions.
- Chiral BICs exhibit high circular polarization, promising for spin-selective applications.
- Atomically-thin transition metal dichalcogenide crystals (TMDCs) host spin-polarized (valley) excitons.
Purpose of the Study:
- To demonstrate a novel application of chiral BICs for strong coupling with valley excitons in TMDCs.
- To investigate the formation and properties of chiral, valley-selective exciton polaritons.
- To understand the energy relaxation dynamics and polarization control of these novel quasiparticles.
Main Methods:
- Fabrication of a metasurface hosting chiral BICs.
- Integration of monolayer WS2 onto the BIC metasurface.
- Characterization using circularly polarized photoluminescence (PL).
- Development of a microscopic model for theoretical analysis.
Main Results:
- Observation of intrinsically chiral, valley-selective exciton polaritons.
- PL intensity and circular polarization enhancement by an order of magnitude compared to uncoupled excitons.
- Demonstration of a direct emission pathway for high-momentum polaritons via Brillouin zone folding.
- Control over spin alignment of upper and lower polaritons via optical excitation polarization.
Conclusions:
- Chiral BICs can induce strong coupling with valley excitons, forming new chiral light-matter quasiparticles.
- The developed system offers enhanced light-matter interaction and spin-selective control.
- Insights into energy relaxation dynamics and suppression of depolarization in polaritons were gained.
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