arXiv subjects

Misha Yu Ivanov

Publications and source records attributed to Misha Yu Ivanov.

5 recordsLinked to original sources

arXiv2025

Propagation of intense squeezed vacuum light in non-linear media

Recent developments in quantum light engineering have enabled the use of infrared bright squeezed vacuum (BSV) femtosecond pulses in highly nonlinear optics, particularly strong field physics and high-harmonic generation. However, theoretical studies were focused on the microscopic interaction with a single atom, neglecting the crucial macroscopic aspect of light propagation through the media. This raises a key question: How does BSV propagates in strongly light-driven nonlinear media and how this affects the generation of non-linear optical signals? We address this question by introducing a fully quantized framework that accounts for the propagation in gas media. We find that atomic ionization caused by strong BSV fluctuations and the associated infrared photon losses introduce decoherence effects that can substantially limit the propagation length in the medium, reduce the harmonic yield, and decrease the number of emitted harmonics at high intensities. However, these effects are not detrimental. We identify conditions under which propagation-induced decoherence is minimized while the generated harmonics remain clearly detectable--an issue of particular importance for future studies exploring the connection between strong-field physics and quantum optics. Our results lay the foundation for future studies of BSV in strong-field physics, nonlinear optics, and ultrafast science, and establish a basis for exploring its propagation through all states of matter in a fully quantized framework.

quant-ph↗

arXiv2024

High-energy, few-cycle light pulses tunable across the vacuum ultraviolet

In the last few decades the development of ultrafast lasers has revolutionized our ability to gain insight into light-matter interactions. The appearance of few-cycle light sources available from the visible to the mid-infrared spectral range and the development of attosecond extreme ultraviolet and x-ray technologies provide for the first time the possibility to directly observe and control ultrafast electron dynamics in matter on their natural time scale. However, few-fs sources have hardly been available in the deep ultraviolet (DUV; 4-6 eV, 300-200 nm) and are unavailable in the vacuum ultraviolet (VUV; 6-12 eV, 200-100 nm) spectral range, corresponding to the photon energies required for valence excitation of atoms and molecules. Here, we generate VUV pulses with $\mu$J energy tunable between 160 and 190 nm via resonant dispersive wave emission during soliton self-compression in a capillary. We fully characterize the pulses in situ using frequency-resolved optical gating based on two-photon photoionization in noble gases. The measurements reveal that in most of the cases the pulses are shorter than 3 fs. These findings unlock the potential to investigate ultrafast electron dynamics with a time-resolution that has been hitherto inaccessible when using VUV pulses.

physics.optics↗

arXiv2023

Control of Spin Polarization through Recollisions

Using only linearly polarized light, we study the possibility of generating spin-polarized photoelectrons from xenon atoms. No net spin polarization is possible, since the xenon ground state is spin-less, but when the photoelectron are measured in coincidence with the residual ion, spin polarization emerges. Furthermore, we show that ultrafast dynamics of the recolliding photoelectrons contribute to an apparent flipping of the spin of the photoelectron, a process that has been completely neglected so far in all analyses of recollision-based processes. We link this phenomenon to the ``spin--orbit clock'' of the remaining ion. These effects arise already in dipole approximation.

physics.atom-ph↗

arXiv2023

Spin-Polarized Photoelectrons in the Vicinity of Spectral Features

It has been shown by Fano (1969) https://doi.org/10.1103/PhysRev.178.131 that photoionization of a c{\ae}sium atom by a laser pulse tuned to the vicinity of a Cooper minimum generates spin-polarized electrons. Here we show that while photoionization of rare gases does not provide large spin polarization in the vicinity of the Cooper minimum, the Fano resonances yield much higher overall spin polarization ($\ge40\%$). The spin polarization increases in angle-resolved photoelectron spectra, and reaches $100\%$ when measured in coincidence with the photoion. We provide a general framework for achieving spin polarization in photoionization irrespective of the ionization regime.

physics.atom-ph↗

arXiv2022

Rydberg Atomic Antenna in Strongly Driven Multi-Electron Atoms

We study the role of intermediate excitations of Rydberg states as an example of Kuchiev's "atomic antenna" in above-threshold ionization of xenon, in particular their effect on the coherence between the spin-orbit-split states of the ion. We focus on the case of a laser frequency close to resonant with the spin-orbit splitting, where a symmetry (parity) argument would preclude any coherence being directly generated by strong-field ionization. Using ab initio simulations of coupled multielectron spin-orbit dynamics in strong laser fields, we show how field-driven rescattering of the trapped Rydberg electrons introduces efficient coupling between the spin-orbit-split channels, leading to substantial coherences, exceeding 10 % for some photon energies.

physics.atom-ph↗