Martin Eckstein
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Theory of ultrafast screening of U in driven charge-transfer insulators: a time-resolved x-ray absorption study Open
Recent seminal experiments have utilized time-resolved x-ray absorption spectroscopy (XAS) to investigate the ultrafast photoinduced renormalization of the electron interaction (“Hubbard U”) in Mott and charge transfer insulators. In this …
View article: Effective equilibrium theory of quantum light-matter interaction in cavities for extended systems and the long wavelength approximation
Effective equilibrium theory of quantum light-matter interaction in cavities for extended systems and the long wavelength approximation Open
When light and matter interact strongly, the resulting hybrid system inherits properties from both constituents, allowing one to modify the material behavior by engineering the surrounding electromagnetic environment. This concept underlie…
View article: The 2025 roadmap to ultrafast dynamics: frontiers of theoretical and computational modeling
The 2025 roadmap to ultrafast dynamics: frontiers of theoretical and computational modeling Open
The exploration of ultrafast phenomena is a frontier of condensed matter research, where the interplay of theory, computation, and experiment is unveiling new opportunities for understanding and engineering quantum materials. With the adve…
Non-Local Correlation Effects in DC and Optical Conductivity of the Hubbard Model Open
Conductivity is one of the most direct probes of electronic systems, yet its theoretical description remains challenging in the presence of strong non-local correlations. In this Letter, we analyze the conductivity of the half-filled singl…
Role of the phonon coupling in driving photoexcited Mott insulators towards a transient superconducting state Open
Understanding light-induced hidden orders is relevant for nonequilibrium materials control and future ultrafast technologies. Hidden superconducting order, in particular, has been a focus of recent experimental and theoretical efforts. In …
Role of the phonon coupling in driving photoexcited Mott insulators towards a transient superconducting state Open
- Understanding light-induced hidden orders is relevant for nonequilibrium materials control and future ultrafast technologies. Hidden superconducting order, in particular, has been a focus of recent experimental and theoretical efforts. I…
Ultrafast Electronic Structure Engineering in 1$T$-TaS$_2$: Role of Doping and Amplitude Mode Dynamics Open
In strongly correlated transition metal dichalcogenides, an intricate interplay of polaronic distortions, stacking arrangement, and electronic correlations determines the nature of the insulating state. Here, we study the response of the e…
Electron-magnon dynamics triggered by an ultrashort laser pulse: A real-time Dual $GW$ study Open
Ultrafast irradiation of correlated electronic systems triggers complex dynamics involving quasi-particle excitations, doublons, charge carriers, and spin fluctuations. To describe these effects, we develop an efficient non-equilibrium app…
High order strong-coupling expansion for X-ray absorption on a dynamically screened impurity Open
Time-resolved X-ray absorption can reveal the dynamical screening of the local Coulomb interaction in strongly correlated photo-excited materials. Here, we focus on the theoretical prediction of X-ray absorption in the presence of dynamica…
The 2025 roadmap to ultrafast dynamics: frontiers of theoretical and computational modeling Open
The exploration of ultrafast phenomena is a frontier of condensed matter research, where the interplay of theory, computation, and experiment is unveiling new opportunities for understanding and engineering quantum materials. With the adve…
Nonthermal order by disorder Open
The quench dynamics of systems exhibiting cooperative or almost competitive orders in equilibrium are explored using Ginzburg-Landau theory plus fluctuations. We show that when the renormalization of the free energy by fluctuations is take…
Solving quantum impurity models in the non-equilibrium steady state with tensor trains Open
We discuss the evaluation of the integrals for intermediate-order diagrams in the self-consistent strong-coupling expansion on the Keldysh contour using Tensor Cross Interpolation (TCI). TCI is used to factorize the nested parts of the int…
Measuring the ultrafast screening of $U$ in photo-excited charge-transfer insulators with time-resolved X-ray absorption spectroscopy Open
Recent seminal experiments have utilized time-resolved X-ray absorption spectroscopy (XAS) to investigate the ultrafast photo-induced renormalization of the electron interaction (''Hubbard $U$'') in Mott and charge transfer insulators. In …
View article: Light-induced insulator–metal transition in Sr <sub>2</sub> IrO <sub>4</sub> reveals the nature of the insulating ground state
Light-induced insulator–metal transition in Sr <sub>2</sub> IrO <sub>4</sub> reveals the nature of the insulating ground state Open
Sr 2 IrO 4 has attracted considerable attention due to its structural and electronic similarities to La 2 CuO 4 , the parent compound of high- T c superconducting cuprates. It was proposed as a strong spin–orbit-coupled J eff = 1/2 Mott in…
View article: Numerically Exact Simulation of Photodoped Mott Insulators
Numerically Exact Simulation of Photodoped Mott Insulators Open
A description of long-lived photodoped states in Mott insulators is challenging, as it needs to address exponentially separated timescales. We demonstrate how properties of such states can be computed using numerically exact steady state t…
Controlling radiative heat flow through cavity electrodynamics Open
Cavity electrodynamics is emerging as a promising tool to control chemical processes and quantum material properties. In this work we develop a formalism to describe the cavity mediated energy exchange between a material and its electromag…
Engineering photon-mediated long-range spin interactions in Mott insulators Open
We investigate the potential to induce long-range spin interactions in a Mott insulator via the quantum electromagnetic field of a cavity. The coupling between light and spins is inherently nonlinear, and occurs via multiphoton processes l…
Effective Equilibrium Theory of Quantum Light-Matter Interaction in Cavities: Extended Systems and the Long Wavelength Approximation Open
When light and matter interact strongly, the resulting hybrid system inherits properties from both constituents, allowing one to modify material behavior by engineering the surrounding electromagnetic environment. This concept underlies th…
View article: Numerically exact simulation of photo-doped Mott insulators
Numerically exact simulation of photo-doped Mott insulators Open
A description of long-lived photo-doped states in Mott insulators is challenging, as it needs to address exponentially separated timescales. We demonstrate how properties of such states can be computed using numerically exact steady state …
Engineering Photon-mediated Long-Range Spin Interactions in Mott Insulators Open
We investigate the potential to induce long-range spin interactions in a Mott insulator via the quantum electromagnetic field of a cavity. The coupling between light and spins is inherently non-linear, and occurs via multi-photon processes…
Photo-induced nonequilibrium states in Mott insulators Open
The study of nonequilibrium phenomena in interacting lattice systems can provide new perspectives on correlation effects, and information on metastable states of matter. Mott insulators are a promising class of systems for nonequilibrium s…
Nonequilibrium DMFT approach to time-resolved Raman spectroscopy Open
Raman spectroscopy uses light scattering to extract information on low-energy excitations of solids. The Raman process is described by diagrams which are fourth order in the light-matter interaction, and in particular the resonant contribu…
View article: Photo-induced charge-transfer renormalization in NiO
Photo-induced charge-transfer renormalization in NiO Open
Photo-doped states in strongly correlated charge transfer insulators are characterized by $d$-$d$ and $d$-$p$ interactions and the resulting intertwined dynamics of charge excitations and local multiplets. Here we use femtosecond x-ray abs…
Light-induced insulator-metal transition in Sr$_2$IrO$_4$ reveals the nature of the insulating ground state Open
Sr$_2$IrO$_4$ has attracted a lot of attention due to its structural and electronic similarities to La$_2$CuO$_4$ which is the parent compound of high-T$_c$ superconducting cuprates. It was proposed to be a strong spin-orbit coupled J$_{ef…
Control of Yu-Shiba-Rusinov States through a Bosonic Mode Open
We investigate the impact of a bosonic degree of freedom on Yu-Shiba-Rusinov states emerging from a magnetic impurity in a conventional superconductor. Starting from the Anderson impurity model, we predict that an additional p-wave conduct…
Vertex-Based Diagrammatic Treatment of Light-Matter-Coupled Systems Open
We propose a diagrammatic Monte Carlo approach for quantum impurity models, which can be regarded as a generalization of the strong-coupling expansion for fermionic impurity models. The algorithm is based on a self-consistently computed th…
Photo-induced charge dynamics in 1$T$-TaS$_2$ Open
Recent theoretical studies showed that the electronic structure of 1$T$-TaS$_2$ in the low-temperature commensurate charge density wave phase exhibits a nontrivial interplay between band-insulating and Mott insulating behavior. This has im…
Dynamical mean-field study of a photon-mediated ferroelectric phase transition Open
The interplay of light and matter gives rise to intriguing cooperative effects in quantum many-body systems. This is even true in thermal equilibrium, where the electromagnetic field can hybridize with collective modes of matter, and virtu…