{"id":{"repo_id":"tu-berlin","oai_identifier":"oai:depositonce.tu-berlin.de:11303/25790"},"canonical_url":"https://search.dev.ndltd.org/etd/tu-berlin/oai:depositonce.tu-berlin.de:11303/25790","repository":{"repo_id":"tu-berlin","name":"Technische Universität Berlin","base_url":"https://api-depositonce.tu-berlin.de/server/oai/request"},"display":{"title":"Nanoscale light-matter interaction of ultrathin materials","abstract":"Materials have always defined the trajectory of human technology and civilization — from the Stone and Bronze Ages to the Silicon Age — and today’s challenges demand materials engineered at the atomic scale. Ultrathin materials offer unique advantages: large oscillator strengths and tunable electro-optical properties by seamless stacking into hybrid platforms. In this cumulative thesis, we develop a unified microscopic framework to explore light–matter interactions in such hybrids when electric fields approach the nanoscale, where classical and local electrodynamics give way to quantum and nonlocal material responses. We begin by deriving the optical response from the Heisenberg equations of motion, self‐consistently coupled to Maxwell’s equations, for three prototypical materials: 1. 2D plasmonic crystals of metal nanoparticles, whose confined intraband dynamics support localized surface‐plasmon resonances and spectrally sharp, spatially extended lattice modes. 2. Landau‐quantized 2D electron gases in GaAs quantum wells under a few tesla perpendicular magnetic fields where the free‐electron Drude response transforms into discrete Landau‐levels, the quantum analogue of the classical cyclotron motion. 3. Transition‐metal dichalcogenide (TMDC) monolayers, hosting tightly bound excitons with binding energies of several hundred meV, due to reduced screening in the surrounding dielectric. Building on these foundations, we develop a fully self‐consistent Maxwell–Bloch formalism to describe electromagnetic energy transfer between a TMDC monolayer and various neighbors — molecules, graphene, other TMDCs, individual metal nanoparticles and plasmonic crystals. The results are detailed for TMDC–plasmonic crystal hybrids, showing that only momentum‐dark excitons couple strongly to confined near fields. Numerical diagonalization reveals a triplet plexcitonic spectrum, two hybrid modes with Rabi splittings beyond 100 meV in the strong coupling regime flanking a weakly coupled bright exciton peak. We proceed by deriving an analytical, simplified version of the momentum-resolved Maxwell-Bloch equations: a three‐coupled‐oscillator model in which all coupling constants are expressed directly in terms of material parameters and geometry. This reduced model agrees quantitatively with both the full numerical solution and available experimental data. Finally, we turn to the prospects for ultrastrong coupling of Landau‐quantized 2D electron gases in nanocavities. The delocalized Landau‐level orbitals introduce inherently nonlocal responses, which we propose to probe through elastic scattering using XUV light with wavelengths similar to the magnetic length, i.e.~the minimal cyclotron radius and, hence, the electron localization length. Although a full ultrastrong‐coupling analysis is reserved for future work, our treatment lays the microscopic groundwork by analyzing the interplay of Landau-quantized electron delocalization and electric fields on the nanoscale. In summary, across the three distinct materials, this thesis quantifies how light–matter coupling strength and characteristic length scales interrelate and provides a unified microscopic theory of nanoscale light-matter interaction in ultrathin materials.","abstract_html":"Materials have always defined the trajectory of human technology and civilization — from the Stone and Bronze Ages to the Silicon Age — and today’s challenges demand materials engineered at the atomic scale. Ultrathin materials offer unique advantages: large oscillator strengths and tunable electro-optical properties by seamless stacking into hybrid platforms. In this cumulative thesis, we develop a unified microscopic framework to explore light–matter interactions in such hybrids when electric fields approach the nanoscale, where classical and local electrodynamics give way to quantum and nonlocal material responses. We begin by deriving the optical response from the Heisenberg equations of motion, self‐consistently coupled to Maxwell’s equations, for three prototypical materials: 1. 2D plasmonic crystals of metal nanoparticles, whose confined intraband dynamics support localized surface‐plasmon resonances and spectrally sharp, spatially extended lattice modes. 2. Landau‐quantized 2D electron gases in GaAs quantum wells under a few tesla perpendicular magnetic fields where the free‐electron Drude response transforms into discrete Landau‐levels, the quantum analogue of the classical cyclotron motion. 3. Transition‐metal dichalcogenide (TMDC) monolayers, hosting tightly bound excitons with binding energies of several hundred meV, due to reduced screening in the surrounding dielectric. Building on these foundations, we develop a fully self‐consistent Maxwell–Bloch formalism to describe electromagnetic energy transfer between a TMDC monolayer and various neighbors — molecules, graphene, other TMDCs, individual metal nanoparticles and plasmonic crystals. The results are detailed for TMDC–plasmonic crystal hybrids, showing that only momentum‐dark excitons couple strongly to confined near fields. Numerical diagonalization reveals a triplet plexcitonic spectrum, two hybrid modes with Rabi splittings beyond 100 meV in the strong coupling regime flanking a weakly coupled bright exciton peak. We proceed by deriving an analytical, simplified version of the momentum-resolved Maxwell-Bloch equations: a three‐coupled‐oscillator model in which all coupling constants are expressed directly in terms of material parameters and geometry. This reduced model agrees quantitatively with both the full numerical solution and available experimental data. Finally, we turn to the prospects for ultrastrong coupling of Landau‐quantized 2D electron gases in nanocavities. The delocalized Landau‐level orbitals introduce inherently nonlocal responses, which we propose to probe through elastic scattering using XUV light with wavelengths similar to the magnetic length, i.e.~the minimal cyclotron radius and, hence, the electron localization length. Although a full ultrastrong‐coupling analysis is reserved for future work, our treatment lays the microscopic groundwork by analyzing the interplay of Landau-quantized electron delocalization and electric fields on the nanoscale. In summary, across the three distinct materials, this thesis quantifies how light–matter coupling strength and characteristic length scales interrelate and provides a unified microscopic theory of nanoscale light-matter interaction in ultrathin materials.","abstract_has_math":false,"creators":["Greten, Lara"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Knorr, Andreas"],"committee_chairs":[],"committee_members":[],"year":2025,"date_issued":"2025","date_published":"2025","updated_at":"2026-07-27T21:28:47Z","subjects":[],"languages":["en"],"rights":[],"rights_urls":["https://creativecommons.org/licenses/by/4.0/"],"identifier_entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://doi.org/10.14279/depositonce-24614"],"render_values":[{"text":"https://doi.org/10.14279/depositonce-24614","href":"https://doi.org/10.14279/depositonce-24614","code":true}]}]},"links":{"outbound_url":"https://depositonce.tu-berlin.de/handle/11303/25790","outbound_label":"Repository record","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Knorr, Andreas"]},{"key":"dc:creator","label":"Author","values":["Greten, Lara"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2025-11-13T16:10:47Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2025-11-13T16:10:47Z"]},{"key":"dc:date.issued","label":"Date","values":["2025"]},{"key":"dc:type","label":"Dc Type","values":["Doctoral Thesis"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]},{"key":"dc:rights.uri","label":"Rights URI","values":["https://creativecommons.org/licenses/by/4.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://depositonce.tu-berlin.de/handle/11303/25790","https://doi.org/10.14279/depositonce-24614"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Materials have always defined the trajectory of human technology and civilization — from the Stone and Bronze Ages to the Silicon Age — and today’s challenges demand materials engineered at the atomic scale. Ultrathin materials offer unique advantages: large oscillator strengths and tunable electro-optical properties by seamless stacking into hybrid platforms. In this cumulative thesis, we develop a unified microscopic framework to explore light–matter interactions in such hybrids when electric fields approach the nanoscale, where classical and local electrodynamics give way to quantum and nonlocal material responses. We begin by deriving the optical response from the Heisenberg equations of motion, self‐consistently coupled to Maxwell’s equations, for three prototypical materials: 1. 2D plasmonic crystals of metal nanoparticles, whose confined intraband dynamics support localized surface‐plasmon resonances and spectrally sharp, spatially extended lattice modes. 2. Landau‐quantized 2D electron gases in GaAs quantum wells under a few tesla perpendicular magnetic fields where the free‐electron Drude response transforms into discrete Landau‐levels, the quantum analogue of the classical cyclotron motion. 3. Transition‐metal dichalcogenide (TMDC) monolayers, hosting tightly bound excitons with binding energies of several hundred meV, due to reduced screening in the surrounding dielectric. Building on these foundations, we develop a fully self‐consistent Maxwell–Bloch formalism to describe electromagnetic energy transfer between a TMDC monolayer and various neighbors — molecules, graphene, other TMDCs, individual metal nanoparticles and plasmonic crystals. The results are detailed for TMDC–plasmonic crystal hybrids, showing that only momentum‐dark excitons couple strongly to confined near fields. Numerical diagonalization reveals a triplet plexcitonic spectrum, two hybrid modes with Rabi splittings beyond 100 meV in the strong coupling regime flanking a weakly coupled bright exciton peak. We proceed by deriving an analytical, simplified version of the momentum-resolved Maxwell-Bloch equations: a three‐coupled‐oscillator model in which all coupling constants are expressed directly in terms of material parameters and geometry. This reduced model agrees quantitatively with both the full numerical solution and available experimental data. Finally, we turn to the prospects for ultrastrong coupling of Landau‐quantized 2D electron gases in nanocavities. The delocalized Landau‐level orbitals introduce inherently nonlocal responses, which we propose to probe through elastic scattering using XUV light with wavelengths similar to the magnetic length, i.e.~the minimal cyclotron radius and, hence, the electron localization length. Although a full ultrastrong‐coupling analysis is reserved for future work, our treatment lays the microscopic groundwork by analyzing the interplay of Landau-quantized electron delocalization and electric fields on the nanoscale. In summary, across the three distinct materials, this thesis quantifies how light–matter coupling strength and characteristic length scales interrelate and provides a unified microscopic theory of nanoscale light-matter interaction in ultrathin materials.","Materialien prägen seit jeher den Fortschritt menschlicher Technologie und Zivilisation — von der Stein- und Bronzezeit bis ins Siliziumzeitalter. Die heutigen Anforderungen benötigen auf atomarer Skala maßgeschneiderte Materialien. Ultradünne Materialien bieten hierbei besondere Vorteile: Sie besitzen hohe Oszillatorstärken und flexible optoelektronische Eigenschaften, z.B. durch Stapeln zu hybriden Plattformen. In dieser kumulativen Dissertation entwickeln wir einen einheitlichen theoretischen Rahmen zur mikroskopischen Beschreibung der Licht-Materie-Wechselwirkung in solchen Hybridsystemen auf der Nanoskala, wo klassische und lokale Elektrodynamik durch quantenmechanische und nichtlokale Materialantworten ersetzt werden muss. Ausgehend von den Heisenberg’schen Bewegungsgleichungen, selbstkonsistent gekoppelt an die Maxwell-Gleichungen, leiten wir beispielhaft die optische Antwort dreier Materialien ab: 1. Zweidimensionale (2D) plasmonische Kristalle, aufgebaut aus Metallnanopartikeln, deren Intraband-Dynamik sowohl lokal begrenzte Plasmonresonanzen als auch spektral scharfe, weit ausgedehnte Gittermoden unterstützt. 2. Landau-quantisierte 2D-Elektronengase in GaAs-Quantenschichten, bei denen sich die klassische Drude-Antwort unter senkrechten Magnetfeldern in diskrete Landau-Niveaus transformiert – das Quantenanalog zur elektronischen, Magnetfeld-induzierten Kreisbewegung. 3. Übergangsmetall-Dichalchogenid (TMDC) Monolagen, in denen durch verminderte dielektrische Abschirmung stark gebundene Exzitonen mit Bindungsenergien im Bereich mehrerer hundert meV existieren. Darauf aufbauend entwickeln wir eine selbstkonsistente Maxwell-Bloch-Theorie zur Beschreibung des elektromagnetischen Energietransfers zwischen einer TMDC-Schicht und verschiedenen Nachbarsystemen – darunter Moleküle, Graphen, andere TMDCs, einzelne Metallnanopartikel und plasmonische Kristalle. Für TMDC–Plasmonik-Hybride zeigt sich, dass nur Impuls-dunkle Exzitonen stark an lokalisierte Nahfelder koppeln. Die numerische Diagonalisierung ergibt ein tripletartiges Plexzitonenspektrum mit zwei Hybridmoden im stark gekoppelten Regime (Rabi-Aufspaltung >100 meV und einem schwach gekoppelten hellen Exziton. Schließlich leiten wir analytisch ein reduziertes Modell her: das Drei-Oszillator-Modell, in dem alle Kopplungskonstanten explizit durch Material- und Geometrieparameter gegeben sind und quantitativ mit numerischen Ergebnissen und experimentellen Daten übereinstimmen. Abschließend richten wir den Blick auf Landau-quantisierte Elektronengase, die in Nanokavitäten das Regime ultrastarker Kopplung erreichen können. Die delokalisierten Landau-Orbitale führen zu intrinsisch nichtlokalen elektromagnetischen Antworten, die wir über elastische Streuung mit XUV-Licht (Wellenlängen im Bereich der magnetischen Länge — also des minimalen Radius der Elektron-Kreisbewegung) experimentell zugänglich machen möchten. Damit legen wir den mikroskopischen Grundstein für eine zukünftige Analyse ultrastarker Kopplung unter Berücksichtigung der Landau-quantisierten, delokalisierten Nanostruktur der Elektronen. Über drei Materialklassen hinweg verknüpft diese Arbeit die Kopplungsstärke von Licht und Materie mit charakteristischen Längenskalen und liefert eine konsistente mikroskopische Theorie der nanoskaligen Licht-Materie Wechselwirkung in ultradünnen Schichten."]},{"key":"dc:title","label":"Title","values":["Nanoscale light-matter interaction of ultrathin materials"]}]}],"canonical_facts":{"dc:contributor.advisor":["Knorr, Andreas"],"dc:creator":["Greten, Lara"],"dc:date.accessioned":["2025-11-13T16:10:47Z"],"dc:date.available":["2025-11-13T16:10:47Z"],"dc:date.issued":["2025"],"dc:description.abstract":["Materials have always defined the trajectory of human technology and civilization — from the Stone and Bronze Ages to the Silicon Age — and today’s challenges demand materials engineered at the atomic scale. Ultrathin materials offer unique advantages: large oscillator strengths and tunable electro-optical properties by seamless stacking into hybrid platforms. In this cumulative thesis, we develop a unified microscopic framework to explore light–matter interactions in such hybrids when electric fields approach the nanoscale, where classical and local electrodynamics give way to quantum and nonlocal material responses. We begin by deriving the optical response from the Heisenberg equations of motion, self‐consistently coupled to Maxwell’s equations, for three prototypical materials: 1. 2D plasmonic crystals of metal nanoparticles, whose confined intraband dynamics support localized surface‐plasmon resonances and spectrally sharp, spatially extended lattice modes. 2. Landau‐quantized 2D electron gases in GaAs quantum wells under a few tesla perpendicular magnetic fields where the free‐electron Drude response transforms into discrete Landau‐levels, the quantum analogue of the classical cyclotron motion. 3. Transition‐metal dichalcogenide (TMDC) monolayers, hosting tightly bound excitons with binding energies of several hundred meV, due to reduced screening in the surrounding dielectric. Building on these foundations, we develop a fully self‐consistent Maxwell–Bloch formalism to describe electromagnetic energy transfer between a TMDC monolayer and various neighbors — molecules, graphene, other TMDCs, individual metal nanoparticles and plasmonic crystals. The results are detailed for TMDC–plasmonic crystal hybrids, showing that only momentum‐dark excitons couple strongly to confined near fields. Numerical diagonalization reveals a triplet plexcitonic spectrum, two hybrid modes with Rabi splittings beyond 100 meV in the strong coupling regime flanking a weakly coupled bright exciton peak. We proceed by deriving an analytical, simplified version of the momentum-resolved Maxwell-Bloch equations: a three‐coupled‐oscillator model in which all coupling constants are expressed directly in terms of material parameters and geometry. This reduced model agrees quantitatively with both the full numerical solution and available experimental data. Finally, we turn to the prospects for ultrastrong coupling of Landau‐quantized 2D electron gases in nanocavities. The delocalized Landau‐level orbitals introduce inherently nonlocal responses, which we propose to probe through elastic scattering using XUV light with wavelengths similar to the magnetic length, i.e.~the minimal cyclotron radius and, hence, the electron localization length. Although a full ultrastrong‐coupling analysis is reserved for future work, our treatment lays the microscopic groundwork by analyzing the interplay of Landau-quantized electron delocalization and electric fields on the nanoscale. In summary, across the three distinct materials, this thesis quantifies how light–matter coupling strength and characteristic length scales interrelate and provides a unified microscopic theory of nanoscale light-matter interaction in ultrathin materials.","Materialien prägen seit jeher den Fortschritt menschlicher Technologie und Zivilisation — von der Stein- und Bronzezeit bis ins Siliziumzeitalter. Die heutigen Anforderungen benötigen auf atomarer Skala maßgeschneiderte Materialien. Ultradünne Materialien bieten hierbei besondere Vorteile: Sie besitzen hohe Oszillatorstärken und flexible optoelektronische Eigenschaften, z.B. durch Stapeln zu hybriden Plattformen. In dieser kumulativen Dissertation entwickeln wir einen einheitlichen theoretischen Rahmen zur mikroskopischen Beschreibung der Licht-Materie-Wechselwirkung in solchen Hybridsystemen auf der Nanoskala, wo klassische und lokale Elektrodynamik durch quantenmechanische und nichtlokale Materialantworten ersetzt werden muss. Ausgehend von den Heisenberg’schen Bewegungsgleichungen, selbstkonsistent gekoppelt an die Maxwell-Gleichungen, leiten wir beispielhaft die optische Antwort dreier Materialien ab: 1. Zweidimensionale (2D) plasmonische Kristalle, aufgebaut aus Metallnanopartikeln, deren Intraband-Dynamik sowohl lokal begrenzte Plasmonresonanzen als auch spektral scharfe, weit ausgedehnte Gittermoden unterstützt. 2. Landau-quantisierte 2D-Elektronengase in GaAs-Quantenschichten, bei denen sich die klassische Drude-Antwort unter senkrechten Magnetfeldern in diskrete Landau-Niveaus transformiert – das Quantenanalog zur elektronischen, Magnetfeld-induzierten Kreisbewegung. 3. Übergangsmetall-Dichalchogenid (TMDC) Monolagen, in denen durch verminderte dielektrische Abschirmung stark gebundene Exzitonen mit Bindungsenergien im Bereich mehrerer hundert meV existieren. Darauf aufbauend entwickeln wir eine selbstkonsistente Maxwell-Bloch-Theorie zur Beschreibung des elektromagnetischen Energietransfers zwischen einer TMDC-Schicht und verschiedenen Nachbarsystemen – darunter Moleküle, Graphen, andere TMDCs, einzelne Metallnanopartikel und plasmonische Kristalle. Für TMDC–Plasmonik-Hybride zeigt sich, dass nur Impuls-dunkle Exzitonen stark an lokalisierte Nahfelder koppeln. Die numerische Diagonalisierung ergibt ein tripletartiges Plexzitonenspektrum mit zwei Hybridmoden im stark gekoppelten Regime (Rabi-Aufspaltung >100 meV und einem schwach gekoppelten hellen Exziton. Schließlich leiten wir analytisch ein reduziertes Modell her: das Drei-Oszillator-Modell, in dem alle Kopplungskonstanten explizit durch Material- und Geometrieparameter gegeben sind und quantitativ mit numerischen Ergebnissen und experimentellen Daten übereinstimmen. Abschließend richten wir den Blick auf Landau-quantisierte Elektronengase, die in Nanokavitäten das Regime ultrastarker Kopplung erreichen können. Die delokalisierten Landau-Orbitale führen zu intrinsisch nichtlokalen elektromagnetischen Antworten, die wir über elastische Streuung mit XUV-Licht (Wellenlängen im Bereich der magnetischen Länge — also des minimalen Radius der Elektron-Kreisbewegung) experimentell zugänglich machen möchten. Damit legen wir den mikroskopischen Grundstein für eine zukünftige Analyse ultrastarker Kopplung unter Berücksichtigung der Landau-quantisierten, delokalisierten Nanostruktur der Elektronen. Über drei Materialklassen hinweg verknüpft diese Arbeit die Kopplungsstärke von Licht und Materie mit charakteristischen Längenskalen und liefert eine konsistente mikroskopische Theorie der nanoskaligen Licht-Materie Wechselwirkung in ultradünnen Schichten."],"dc:identifier.uri":["https://depositonce.tu-berlin.de/handle/11303/25790","https://doi.org/10.14279/depositonce-24614"],"dc:language.iso":["en"],"dc:rights.uri":["https://creativecommons.org/licenses/by/4.0/"],"dc:title":["Nanoscale light-matter interaction of ultrathin materials"],"dc:type":["Doctoral Thesis"]},"updated_at":"2026-07-27T21:28:47Z"}