AG Nichtlineare Optik und Quantenelektronik

8 Items

Recent Submissions
Many electrons and the photon field

Buchholz, Florian Konrad Friedrich (2021)

Recent experimental progress in the field of cavity quantum electrodynamics allows to study the regime of strong interaction between quantized light and complex matter systems. Due to the coherent coupling between photons and matter-degrees of freedom, polaritons - hybrid light-matter quasiparticles - emerge, which can significantly influence matter properties and complex process such as chemic...

Non-Markovian open quantum many-body system dynamics

Finsterhölzl, Regina Anna (2021)

The study of open quantum systems forms one of the main problems of modern physics. This thesis aims at contributing to this field, and focuses on the investigation of non-Markovian dynamics of open quantum systems. Here, as a special case, quantum many-body systems provide for a rich field of research. With the ability to control them being of essential importance for the development of quantu...

Quantization of quasinormal modes in dissipative media

Franke, Sebastian Robert (2020)

Light-matter interactions in dissipative nanophotonic or nanoplasmonic systems is a major topic in modern quantum optics and quantum plasmonics. One of the main challenges from the theoretical point of view is to rigorously quantize the light in these systems and to express the electric field operator in terms of discrete photon annihilation and creation operators. This is a highly non-trivial ...

Coherent coupling of individual quantum dots measured with phase-referenced two-dimensional spectroscopy: Photon echo versus double quantum coherence

Delmonte, Valentin ; Specht, Judith F. ; Jakubczyk, Tomasz ; Höfling, Sven ; Kamp, Martin ; Schneider, Christian ; Langbein, Wolfgang ; Nogues, Gilles ; Richter, Marten ; Kasprzak, Jacek (2017)

We employ two-dimensional (2D) coherent, nonlinear spectroscopy to investigate couplings within individual InAs quantum dots (QDs) and QD molecules. Swapping pulse ordering in a two-beam sequence permits one to distinguish between rephasing and nonrephasing four-wave mixing (FWM) configurations. We emphasize the nonrephasing case, allowing one to monitor two-photon coherence dynamics. Respectiv...

Using Matrix-Product States for Open Quantum Many-Body Systems: Efficient Algorithms for Markovian and Non-Markovian Time-Evolution

Finsterhölzl, Regina ; Katzer, Manuel ; Knorr, Andreas ; Carmele, Alexander (2020-09-04)

This paper presents an efficient algorithm for the time evolution of open quantum many-body systems using matrix-product states (MPS) proposing a convenient structure of the MPS-architecture, which exploits the initial state of system and reservoir. By doing so, numerically expensive re-ordering protocols are circumvented. It is applicable to systems with a Markovian type of interaction, where ...

Surface phase diagrams including anharmonic effects via a replica-exchange grand-canonical method

Zhou, Yuanyuan (2020)

Phase diagrams of surfaces in a reactive atmosphere provide detailed information on surface composition and structure at thermodynamic equilibrium at realistic conditions, e.g., temperature (T ) and pressure (p) of the reactive gas. The atomistic structure is a prerequisite to understand and control electronic properties and function of surfaces. For decades, “ab initio atomistic thermodynamic”...

Fully coupled Maxwell-Kohn-Sham systems

Jestädt, René (2020)

Light-matter interactions have always been an essential aspect of research. They cover the main properties of light and matter in atomic and molecular systems, in condensed phase, in chemical reactions, and in optics. This thesis presents a feasible implementation to simulate three- imensional, real-time, real-space, self-consistently coupled light-matter systems based on the theoretical backgr...

Revisiting quantum feedback control: disentangling the feedback‐induced phase from the corresponding amplitude

Barkemeyer, Kisa ; Finsterhölzl, Regina ; Knorr, Andreas ; Carmele, Alexander (2019-10-11)

Coherent time‐delayed feedback allows the control of a quantum system and its partial stabilization against noise and decoherence. The crucial and externally accessible parameters in such control setups are the round‐trip‐induced delay time τ and the frequencies ω of the involved optical transitions which are typically controllable via global parameters like temperature, bias, or strain. They i...