arXiv subjects

Vladislav S. Yakovlev

Publications and source records attributed to Vladislav S. Yakovlev.

23 records · Page 2Linked to original sources

arXiv2012

Dressed bound states for attosecond dynamics in strong laser fields

We propose a theoretical approach for the interpretation of pump-probe measurements where an attosecond pulse is absorbed in the presence of an intense laser pulse. This approach is based on abstractly defined dressed bound states, which capture the essential aspects of the interaction with the laser pulse and facilitate a perturbative description of transitions induced by the attosecond pulse. Necessary properties of dressed bound states are defined and various choices are discussed and compared to accurate numerical solutions of the time-dependent Schroedinger equation.

quant-ph↗

arXiv2011

Theory of attosecond transient absorption spectroscopy of strong-field-generated ions

Strong-field ionization generally produces ions in a superposition of ionic eigenstates. This superposition is generally not fully coherent und must be described in terms of a density matrix. A recent experiment [E. Goulielmakis et al., Nature 466, 739 (2010)] employed attosecond transient absorption spectroscopy to determine the density matrix of strong-field-generated Kr+ ions. The experimentally observed degree of coherence of the strong-field-generated Kr+ ions is well reproduced by a recently developed multichannel strong-field-ionization theory. But there is significant disagreement between experiment and theory with respect to the degree of alignment of the Kr+ ions. In the present paper, the theory underlying attosecond transient absorption spectroscopy of strong-field-generated ions is developed. The theory is formulated in such a way that the nonperturbative nature of the strong-field-ionization process is systematically taken into account. The impact of attosecond pulse propagation effects on the interpretation of experimental data is investigated both analytically and numerically. It is shown that attosecond pulse propagation effects cannot explain why the experimentally determined degree of alignment of strong-field-generated Kr+ ions is much smaller than predicted by existing theory.

physics.atom-ph↗

arXiv2010

The direct evaluation of attosecond chirp from a streaking measurement

We derive an analytical expression, from classical electron trajectories in a laser field, that relates the breadth of a streaked photoelectron spectrum to the group-delay dispersion of an isolated attosecond pulse. Based on this analytical expression, we introduce a simple, efficient and robust procedure to instantly extract the attosecond pulse's chirp from the streaking measurement.

physics.optics↗

arXiv2010

Laser Dressed Scattering of an Attosecond Electron Wave Packet

We theoretically investigate the scattering of an attosecond electron wave packet launched by an attosecond pulse under the influence of an infrared laser field. As the electron scatters inside a spatially extended system, the dressing laser field controls its motion. We show that this interaction, which lasts just a few hundreds of attoseconds, clearly manifests itself in the spectral interference pattern between different quantum pathways taken by the outgoing electron. We find that the Coulomb-Volkov approximation, a standard expression used to describe laser-dressed photoionization, cannot properly describe this interference pattern. We introduce a quasi-classical model, based on electron trajectories, which quantitatively explains the laser-dressed photoelectron spectra, notably the laser-induced changes in the spectral interference pattern.

quant-ph↗

arXiv2010

Attosecond streaking enables the measurement of quantum phase

Attosecond streaking, as a measurement technique, was originally conceived as a means to characterize attosecond light pulses, which is a good approximation if the relevant transition matrix elements are approximately constant within the bandwidth of the light pulse. Our analysis of attosecond streaking measurements on systems with complex response to the photoionizing pulse establishes a relation between the momentum-space wave function of the outgoing electron and the result of conventional retrieval algorithms. This finding enables the measurement of the quantum phase associated with bound-continuum transition matrix elements.

physics.atom-ph↗