Alexander Croy

High-order harmonic generation (HHG) in solids offers a promising route to compact ultrafast sources of quantum light, but its efficiency and coherence are limited by ultrafast dephasing of laser-driven electron–hole polarization. Although widely described by a phenomenological coherence time, the microscopic origin of this dephasing has remained unresolved. Here, we combine wavelength-dependent HHG measurements in monolayer and bulk semiconductors with ab initio many-body calculations of electron–phonon scattering and strong-field simulations. We show that the measured wavelength scaling of the HHG yield is quantitatively reproduced only when semiconductor Bloch equations incorporate momentum-dependent dephasing derived from first principles scattering rates. The calculations reveal that strong-field-driven carriers rapidly enter regions of the Brillouin zone with enhanced electron–phonon scattering, giving rise to effective few-femtosecond dephasing. Our results establish a microscopic foundation for dephasing in solid-state HHG and provide a framework for engineering coherence in strongly driven solids for quantum photonic applications.

The Berry connection is a gauge-dependent quantity frequently used to describe the optical response of solids. Its evaluation requires a k derivative with respect to the cell-periodic part of the Bloch functions and is commonly calculated in the Wannier basis by using overlap matrices of cell-periodic parts of Bloch functions at neighboring k points. So far, all proposed interpolation schemes for the Berry connection do not account for the matrix structure of the overlap matrices explicitly but treat the matrix elements as independent, or only distinguish between diagonal and off-diagonal entries. In this work, we propose a self-consistent interpolation scheme based on the matrix logarithm resulting in a strongly improved accuracy. Furthermore, we discuss how the basis set incompleteness of the bands used in the calculation imposes constraints on the accuracy. We quantify the basis incompleteness based on the singular values of the overlap matrices and relate it to the invariant part of the spread functional Ω I of the Wannier functions. Numerical calculations for monolayer MoS 2 and bulk Si demonstrate that the proposed interpolation scheme is much less sensitive to the Wannierization details and leads to an improved quality of the velocity matrix and the optical conductivity.

This report studies the dynamic behavior of metallopolymers, by rheology, Raman spectroscopy and modelling. The observed changes are related to thermal-induced morphological changes of the polymer matrix in addition to changes of the metal complex.

Recently, the size-dependence of high-order harmonic generation (HHG) in quantum dots (QDs) has been investigated experimentally. In particular, for longer driving wavelengths and quantum dots smaller than 3 nm, HHG was strongly suppressed; however, there is no computational model capable of describing the strong-field response of such systems. In this work, we introduce a computationally efficient three-dimensional real-space tight-binding model specifically designed for the simulation of HHG in confined systems. The model parameters are meticulously derived from density functional theory calculations for the semiconductor bulk, followed by a process of Wannierization. Our findings demonstrate that the proposed model accurately captures the observed dependency of the HHG yield on the quantum dot size. In addition, we simulate the HHG yield for elliptically polarized pulses for different QD-sizes and driving wavelengths up to 5 μm. The proposed model fills the theoretical void in simulating HHG within medium-sized nanostructures, which cannot be described by methods applied for periodic solids, or small molecules or atoms.

Semiconducting single‐walled carbon nanotubes (sc‐SWCNTs) are of great potential for vapor sensing. However, sc‐SWCNTs lack recognition features for discriminating between sparsely functionalized moieties, molecules with similar structural features, and enantiomer pairs. This becomes a major setback in discriminating between volatile organic compounds (VOCs). Here, we used two galactosides decorated with aromatic groups as a recognition layer in chemoresistive sc‐SWCNT sensors to produce chiral preference toward six terpenoid enantiomers. The multichirality and multifunctionality of a monosaccharide scaffold were exploited to maximize the limited interacting features associated with VOCs. The developed system establishes a robust and tunable platform for enantioselective gas sensing.

Two-dimensional polymers (2DPs) are an interesting class of polymers due to their reticular synthetic assembly, which make them an ideal platform for designing materials with specific target properties. Predicting and understanding their elastic behavior is crucial for their application. However, a realistic calculation of their properties remains computationally challenging due to the ubiquitous presence of defects in synthesized 2DPs. Here, we introduce a coarse-graining (CG) approach based on elastic beams called MikadoRR with parameters extracted from a simple regression-based fitting. This approach allows us to accurately calculate the elastic properties of defective 2DPs up to the microscale. Furthermore, we show that design principles of 2DPs for tailored elastic properties can be derived from this CG model.

This study presents a detailed comparative study of lactone‐based electrolytes (γ‐valerolactone, GVL and γ‐butyrolactone, GBL) combined with lithium imide‐based salts, namely lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium bis(fluoromethanesulfonyl)imide (LiFSI). Propylene carbonate is employed as a reference electrolyte solvent. The physicochemical properties of these electrolyte systems are determined experimentally and further calculated using our developed computational model. Besides, in‐silico investigations are used to reveal valuable insights into the molecular interactions of the electrolyte components, such as self‐diffusion coefficients and radial distribution functions. Furthermore, the suitability of lactone‐based electrolytes for electrochemical applications is demonstrated by their promising rate capability and cycling stability over 200 cycles in graphite half‐cells, especially with 1 M LiTFSI and 2 wt% vinylene carbonate, together with their favorable performance on lithium iron phosphate. An excellent capacity retention achieved in a full‐cell configuration (> 80% after 200 cycles) further validates the potential of lactones as battery solvent alternatives, with GVL standing out due to its bio‐based origin.