A5041925088- Laser-Matter Interactions and Applications
- Semiconductor Quantum Structures and Devices
- Advanced Fiber Laser Technologies
- Quantum Dots Synthesis And Properties
- Terahertz technology and applications
- Chalcogenide Semiconductor Thin Films
- Speech and Audio Processing
- Music and Audio Processing
- Spectroscopy and Quantum Chemical Studies
- Laser-Plasma Interactions and Diagnostics
- Perovskite Materials and Applications
- Quantum and electron transport phenomena
- 2D Materials and Applications
- Superconducting Materials and Applications
- Particle accelerators and beam dynamics
- Quantum optics and atomic interactions
- Advanced Data Compression Techniques
- Topic Modeling
- nanoparticles nucleation surface interactions
- MXene and MAX Phase Materials
- Speech Recognition and Synthesis
- Magnetic confinement fusion research
- Machine Learning in Healthcare
- Molecular Junctions and Nanostructures
- Nonlinear Optical Materials Studies
University of Vienna
2018-2023
Nuance Communications (Austria)
2022-2023
Nuance Communications (United States)
2021
Max Planck Institute of Quantum Optics
2013-2018
Max Planck Society
2013-2014
ITMO University
2008-2011
St Petersburg University
2007-2011
State Optical Institute named after SI Vavilov
2004-2006
The advent of visible-infrared laser pulses carrying a substantial fraction their energy in single field oscillation cycle has opened new era the experimental investigation ultrafast processes semiconductors and dielectrics (bulk as well nanostructured), motivated by quest for ultimate frontiers electron-based signal metrology processing. Exploring ways to approach those requires insight into physics underlying interaction strong high-frequency (optical) fields with electrons moving periodic...
Moiré effects in vertical stacks of two-dimensional crystals give rise to new quantum materials with rich transport and optical phenomena that originate from modulations atomic registries within moiré supercells. Due finite elasticity, however, the superlattices can transform moiré-type periodically reconstructed patterns. Here we expand notion such nanoscale lattice reconstruction mesoscopic scale laterally extended samples demonstrate consequences studies excitons MoSe2-WSe2...
The optical properties of monolayer and bilayer transition metal dichalcogenide semiconductors are governed by excitons in different spin valley configurations, providing versatile aspects for van der Waals heterostructures devices. We present experimental theoretical studies exciton energy splittings external magnetic field neutral charged WSe$_2$ crystals embedded a effect device active doping control. develop methods to calculate the $g$-factors from first principles tight-binding all...
Layered two-dimensional materials exhibit rich transport and optical phenomena in twisted or lattice-incommensurate heterostructures with spatial variations of interlayer hybridization arising from moir\'e interference effects. Here, we report experimental theoretical studies excitons heterobilayers heterotrilayers transition metal dichalcogenides. Using MoSe$_2$-WSe$_2$ stacks as representative realizations van der Waals bilayer trilayer heterostructures, observe contrasting signatures...
We predict that a direct band gap semiconductor (GaAs) resonantly excited by strong ultrashort laser pulse exhibits novel regime: kicked anharmonic Rabi oscillations. In this regime, oscillations are strongly coupled to intraband motion, and interband transitions mainly take place when electrons pass near the Brillouin zone center where electron populations undergo very rapid changes. The asymmetry of residual population distribution induces an electric current controlled carrier-envelope...
Nonlinear interactions between ultrashort optical waveforms and solids can be used to induce steer electric currents on femtosecond (fs) timescales, holding promise for electronic signal processing at PHz (10 15 Hz) frequencies [Nature 493, 70 (2013)].So far, this approach has been limited insulators, requiring extreme peak fields (>1 V∕Å) intensities (>10 13 W∕cm 2 ).Here, we show all-optical generation control of in a semiconductor relevant high-speed high-power (opto)electronics, gallium...
We have investigated the polarization response of a dielectric to intense few-cycle laser pulses with focus on interband tunnelling. Once charge carriers are created in an initially empty conduction band, they make significant contribution response. In particular, coherent superposition conduction- and valence-band states results quantum beats. This quantum-beat part is affected by excitation dynamics attosecond-scale motion field. Our analysis shows that, onset Bloch oscillations or...
We propose a theory of optically induced currents in dielectrics and wide gap semiconductors exposed to nonresonant ultrashort laser pulse with stabilized carrier-envelope phase. To describe strong-field electron dynamics, equations for the density matrix have been solved self-consistently macroscopic electric field inside medium, which we model by one-dimensional potential. provide detailed analysis physically important quantities (band populations, polarization, transferred charge),...
Nanocrystals of AgInS2 demonstrate giant Stokes shifts ∼1 eV, the nature which is still not clearly understood. We propose a theoretical model this phenomenon, bringing together several different mechanisms previously considered only separately. take into account contribution electron–electron interaction with hybrid density functional theory, as well renormalization energy spectrum due to electron–phonon coupling. Furthermore, we consider presence at least one point defect responsible for...
The resonant energy transfer due to weak electrostatic interaction in a system of two quantum dots has been theoretically investigated. probability this process the case direct-gap semiconductor calculated assuming that between dot donor electrons and acceptor is described by screened Coulomb potential. This allows one consider all important multipole terms correctly analyze dipole-forbidden transitions. It found from states plays an essential role process. anisotropy temperature dependence...
We present a theoretical study of the stationary photoluminescence two, direct-gap, semiconductor nanocrystals, taking into account electronic excitation energy-transfer processes due to electrostatic interaction. The results obtained here allow for incoherent reversible energy transport that occurs when intraband relaxation rate in quantum dot acceptor is comparable to, or less than, rate. investigate secondary emission two different level schemes can be realized experimentally, obtain...
The coherent coupling of quantum dots is a sensitive indicator the energy and phase relaxation processes taking place in nanostructure components. We formulate theory low-temperature, stationary photoluminescence from quantum-dot molecule composed two spherical whose electronic subsystems are resonantly coupled via Coulomb interaction. show that leads to hybridization first excited states dots, manifesting itself as pair peaks with intensities spectral positions strongly dependent on...
We present a theoretical description of the first-order scattering interacting electrons and holes in double quantum dot. Assuming infinitely high walls, strong confinement, two-band approximation, we derive general expressions for two-particle matrix elements screened Coulomb potential. also determine selection rules different channels consider special cases where corresponding can be represented by simple analytical expressions. Numerical calculations an analysis their dependence on...
We present a novel multi-channel front-end based on channel shortening with the Weighted Prediction Error (WPE) method followed by fixed MVDR beamformer used in combination recently proposed self-attention-based (SACC) scheme, for tackling distant ASR problem. show that system as part of ContextNet end-to-end (E2E) outperforms leading systems demonstrated 21.6% reduction relative WER LibriSpeech playback dataset. also how dereverberation prior to beam-forming is beneficial and compare WPE...
We develop the theory of pure dephasing in a solid exposed to an ultrashort laser pulse beyond commonly used Markov approximation. This approach takes into account finite cutoff energy bath and can be applied both many-particle phonon environments. With numerical simulations performed with time-dependent Hartree-Fock equations, we investigate how excitation probability high-harmonic generation are described by different models decoherence. It is shown that rates allow for temporally high...
Moiré effects in twisted or lattice-incommensurate vertical assemblies of two-dimensional crystals give rise to a new class quantum materials with rich transport and optical phenomena, including correlated electron physics flat bands bilayer graphene moiré excitons semiconductor heterostructures. These phenomena arise from modulations interlayer hybridization on the nanoscale spatially varying atomic registries supercells. Due finite elasticity, however, lattices marginally-twisted...
We present a novel method for extracting neural embeddings that model the background acoustics of speech signal. The extracted are used to estimate specific parameters related acoustic properties signal in non-intrusive manner, which allows be explainable terms those parameters. illustrate value these by performing clustering experiments on unseen test data and show proposed achieve mean F1 score 95.2\% three different tasks, outperforming significantly WavLM based embeddings. also can...
We explore the recently proposed explainable acoustic neural embedding~(XANE) system that models background acoustics of a speech signal in non-intrusive manner. The XANE embeddings are used to estimate specific parameters related properties which allows be terms those parameters. perform ablation studies on and show estimating all jointly has an overall positive effect. Furthermore, we illustrate value by performing clustering experiments unseen test data achieve mean F1 score 92\% for...