arXiv subjects

Johannes Düreth

Publications and source records attributed to Johannes Düreth.

10 recordsLinked to original sources

arXiv2026

Encapsulated macroscopic WS$_2$ monolayers enable room-temperature exciton-polariton lattices

Large-area, optically homogeneous monolayer semiconductors are a critical prerequisite for scalable room-temperature polaritonics and for realizing polariton lattices extending across many unit cells. Yet, the small size, optical inhomogeneity, and device-to-device variability of conventional exfoliated flakes have remained major obstacles. Here, we overcome these limitations using 1-dodecanol-encapsulated WS$_2$ monolayers that combine millimeter-scale coverage with remarkably uniform optical properties over lateral distances approaching $300\,$$μ\mathrm{m}$. Integrated into a tunable open microcavity, these monolayers exhibit robust room-temperature exciton-photon strong coupling, evidenced by a pronounced anti-crossing and a Rabi splitting of $\hbar Ω_{\mathrm{R}} \approx 31\,\mathrm{meV}$. Leveraging the exceptional uniformity of this platform, we realize a two-dimensional polaritonic kagome lattice and directly resolve its characteristic band structure. Angle-resolved spectroscopy reveals Dirac dispersive bands together with a weakly dispersive flat-band-like branch within the $s$-band, in good agreement with a linear non-interacting model. Complementary momentum- and real-space imaging further identifies the associated bond-centered and site-centered mode profiles. These results establish large-area WS$_2$ monolayers in open microcavities as a scalable platform for engineering polariton band structures and exploring synthetic quantum materials under ambient conditions.

cond-mat.mes-hall↗

arXiv2026

Lattice quantum electrodynamics of a molecular emitter in a topological gap

Engineering the photonic environment using lattices of coupled resonators, which we refer to as lattice quantum electrodynamics (QED), provides a route to control both the spontaneous emission of individual quantum emitters and the photon-mediated interactions between them. Here we introduce an optical lattice QED platform based on individual dibenzoterrylene (DBT) molecules embedded in anthracene crystals and coupled to lattices of open optical microcavities. This hybrid architecture benefits from narrow-linewidth molecular emitters, site-resolved optical access, engineered coupled-resonator bands, and compatibility with established molecular frequency-tuning techniques. As a proof-of-principle demonstration, we observe emitter-photon bound states formed when the optical transition of a single molecule is tuned to the band gap of a Su-Schrieffer-Heeger (SSH) cavity lattice. These in-gap states display directional localization and photon emission on a single sublattice, inherited from the vacancy-induced topological edge modes of the underlying SSH lattice. Our results establish open-cavity lattices coupled to DBT molecules as a versatile architecture for engineering many-emitter quantum optical systems with controllable photon-mediated interactions.

quant-ph↗

arXiv2026

Deterministic Transferable Planar Dielectric Mirrors for Investigating Strong Light-Matter Coupling

Optical cavities play a central role in photonic and quantum technologies by enhancing light-matter interactions. In semiconductor microcavities, achieving high quality (Q) factors typically relies on sophisticated epitaxial growth techniques, such as molecular beam epitaxy, which offer atomic-scale precision but are costly and limited in material compatibility. For dielectric microcavities, high Q factors can be achieved using dielectric Bragg mirrors. However, conventional deposition techniques for the top mirrors, such as plasma-enhanced chemical vapor deposition or sputtering, can damage embedded emitters. This limitation is particularly severe for van der Waals materials, especially atomically thin semiconductors. Moreover, the conventional top-mirror deposition can cover or degrade predefined metal contacts. Recovering electrical access typically requires additional lithography and etching steps. Here, a deterministic dry-transfer approach is developed to fabricate complete dielectric microcavities using both top and bottom SiO_2/TiO_2 Bragg mirrors without post-growth lift-off processes, reaching a Q factor ~ 4x10^3. Using a WS_2 monolayer as the active medium, clear signatures of strong exciton-photon coupling are observed at both room temperature and cryogenic temperatures. These results demonstrate an efficient cavity fabrication approach that preserves the integrity of the emitter of layered materials, enabling next generation integrated photonic devices.

physics.optics↗

arXiv2025

Hybrid confinement techniques for polariton simulators

Exciton-polariton III-V semiconductor microcavities provide a robust platform for emulating complex Hamiltonians, enabling topological photonics and quantum simulation for advanced photonic functionalities. Here, we introduce two novel fabrication techniques - etch-and-oversputter and deposit-and-oversputter - that overcome limitations of traditional photonic confinement. Both use structured, locally elongated semiconductor cavities to create deep, highly controllable potentials, while leveraging high-quality GaAs-based materials, which achieve excellent Q-factors. A sputtered all-dielectric top mirror introduces an innovative hybrid approach, simplifying fabrication while maintaining quality compared to deep ion etching. Utilizing a Kagome lattice as a benchmark, we show high-quality optical band structures previously inaccessible with deep etching. Furthermore, we study a two-dimensional breathing Kagome lattice and demonstrate polariton lasing from a zero-dimensional corner mode, confirming precise control over couplings and tight polariton localization. These methods enable fabrication of intricate lattices, including higher-order topological insulators, or on-chip quantum regimes utilizing the polariton blockade mechanism due to tight photonic confinement.

physics.optics↗

arXiv2025

Probing Local Topology in a Disordered Higher-Order Topological Insulator

Higher-order topology is prized for its ability to realize lower-dimensional boundary states which are stable beyond fine-tuning. However, disorder presents a failure mechanism that can destroy topological in-gap states. Here, we investigate a disordered two-dimensional polariton lattice and employ the spectral localizer framework to define a real-space topological index rooted in crystalline spatial symmetries. This framework enables direct real-space mapping of topology beyond conventional momentum-space classifications, confirming the presence of corner and edge modes in this generalized Su-Schrieffer-Heeger model. Furthermore, it can directly quantify topological protection of a state. We leverage the versatility of our platform to experimentally realize normally distributed, random disorder and find that the corner states persist until the spectral gap closes. Experimentally, this corresponds to a disorder strength of approximately one quarter of the spectral gap. The spectral localizer accurately identifies the disorder strength at which the bandgap closes, establishing the framework as a predictive tool for every finite size system. Our results broaden the design principles for higher-order topological insulators and open the way towards imple menting disorder-resilient devices for robust lasing, light-routing, and quantum computation.

physics.optics↗

arXiv2025

Direct experimental access to the bulk band inversion in a topological metamaterial

Topological phases in exciton-polaritons and other metamaterial platforms have attracted significant attention due to their flexibility as Hamiltonian simulators. In previous works, signatures of topology have mainly been investigated from the perspective of edge states - strongly localised modes with exponentially decaying intensity into the bulk. While these edge states have become the hallmark of topological systems as they can facilitate non-reciprocal transport in potential applications, the topology is fundamentally encoded in the bulk band structure. In particular, the momentum-dependence of the eigenstates, i.e., the wave functions, determines the topology, usually reflected in a bulk band inversion. We present a band inversion in the paradigmatic Su-Schrieffer-Heeger (SSH) model, characterised by a reversal of the sublattice symmetry, quantified by the expectation value $\langle σ_\mathrm{x} \rangle$, when going from the centre of the Brillouin zone to the zone boundary. Here, we show direct experimental access to this bulk band inversion in SSH exciton-polariton chains, using two-dimensional momentum-space ($k$-space) mapping - without the need for real-space imaging. This technique enables the direct observation of the momentum-dependent inversion of the sublattice symmetry in the bulk bands, providing a unique perspective on topological phases beyond conventional edge state measurements. Our approach establishes effective momentum-resolved sublattice phase measurements as a powerful tool for accessing the wave function and bulk topology in photonic and polaritonic systems and beyond.

physics.optics↗

arXiv2025

Observation of Kardar-Parisi-Zhang universal scaling in two dimensions

Equilibrium and nonequilibrium states of matter can exhibit fundamentally different behavior. A key example is the Kardar-Parisi-Zhang universality class in two spatial dimensions (2D KPZ), where microscopic deviations from equilibrium give rise to macroscopic scaling laws without equilibrium counterparts. While extensively studied theoretically, direct experimental evidence of 2D KPZ scaling has remained limited to interface growth so far. Here, we report the observation of universal scaling consistent with the KPZ universality class in 2D exciton-polariton condensates -- quantum fluids of light that are inherently driven and dissipative, thus breaking equilibrium conditions. Using momentum-resolved photoluminescence spectroscopy as well as space- and time-resolved interferometry, we probe the phase correlations across microscopically different systems, varying drive conditions in two distinct lattice geometries. Our analysis reveals correlation dynamics and scaling exponents in excellent agreement with 2D KPZ predictions. These results establish exciton-polariton condensates as a robust experimental platform for exploring 2D nonequilibrium universality quantitatively, and open new avenues for investigating the emergence of coherence in interacting quantum systems far from equilibrium.

quant-ph↗

arXiv2025

Artificial Gauge Fields and Dimensions in a Polariton Hofstadter Ladder

Artificial gauge fields allow uncharged particles to mimic the behavior of charged particles subjected to magnetic fields, providing a powerful platform for exploring topological physics. Neutral particles, like photons, are typically unaffected by real magnetic fields. However, it is possible to introduce artificial gauge fields that control the effective dynamics of these neutral particles. Topological exciton-polariton lasers have attracted considerable interest, in part due to the wide range of tunable system parameters, but often require strong magnetic fields to realise propagating topological edge states. Here we show, that by using an artificial gauge field the topological Hall effect in a micron-scale micropillar chain is experimentally realised, exploiting the circular polarisation of polaritons as an artificial dimension. By careful rotational alignment of elliptical micropillars, we introduce an effective plaquette phase that induces strictly polarisation-dependent edge-state propagation, demonstrating non-reciprocal transport of the polariton pseudospins. Our results demonstrate that the dimensionality limitation of topological interface states as well as requirements for strong external magnetic fields in coupled topological laser arrays can be overcome by utilizing polarisation effects and careful engineering of the potential landscape. Our results open new ways towards the implementation of topological polariton lattices and related optically active devices with additional artificial dimension.

physics.optics↗

arXiv2024

Enwrapped Perylene Bisimide Enables Room Temperature Polariton Lasing and Photonic Lattices

Perylene bisimides (PBIs) are organic dyes with photoluminescence quantum yields (PLQY) close to unity in solution and great thermal and photo-chemical stability. These features alongside the tunability of their solid-state packing arrangement via chemical functionalization make this material class an excellent candidate for exciton-polariton lasing at room temperature. Polariton lasing is well understood in III-V semiconductors at cryogenic temperatures, however, the search for emitter materials for robust and versatile room temperature applications is ongoing. While e.g. perovskites and several organic materials have been identified to support polariton lasing, many of these materials lack tunability and long-term stability under ambient conditions. Here, we fabricate optical microcavities using a strongly enwrapped PBI chromophore with prevailing monomer-like absorption and emission properties in the solid state. Voluminous bay-substituents prevent stacking induced PLQY-quenching, thereby enabling polariton lasing at room temperature. Additionally, photonic confinement in single hemispheric resonators is demonstrated leading to localized polaritonic modes with discrete energies, as well as optical lattices revealing distinct polaritonic band-structures. Due to the possibility of tunable properties by the precise control of the solid-state packing arrangement of PBI emitters, our results pave the way for polarization-dependent light-matter coupling, including topological photonic effects within oriented crystalline thin-film microcavity structures.

physics.optics↗

arXiv2024

Dirac Cones and Room Temperature Polariton Lasing Evidenced in an Organic Honeycomb Lattice

Artificial one- and two-dimensional lattices have emerged as a powerful platform for the emulation of lattice Hamiltonians, the fundamental study of collective many-body effects, and phenomena arising from non-trivial topology. Exciton-polaritons, bosonic part-light and part-matter quasiparticles, combine pronounced nonlinearities with the possibility of on-chip implementation. In this context, organic semiconductors embedded in microcavities have proven to be versatile candidates to study nonlinear many-body physics and bosonic condensation, and in contrast to most inorganic systems, they allow the use at ambient conditions since they host ultra-stable Frenkel excitons. We implement a well-controlled, high-quality optical lattice that accommodates light-matter quasiparticles. The realized polariton graphene presents with excellent cavity quality factors, showing distinct signatures of Dirac cone and flatband dispersions as well as polariton lasing at room temperature. This is realized by filling coupled dielectric microcavities with the fluorescent protein mCherry. We demonstrate the emergence of a coherent polariton condensate at ambient conditions, taking advantage of coupling conditions as precise and controllable as in state-of-the-art inorganic semiconductor-based systems, without the limitations of e.g. lattice matching in epitaxial growth. This progress allows straightforward extension to more complex systems, such as the study of topological phenomena in two-dimensional lattices including topological lasers and non-Hermitian optics.

physics.optics↗