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We derive the closed form Cramer-Rao bound (CRB) expressions for joint estimation of time delay and Doppler shift with unknown signals with possibly known structure. The results are especially useful for passive radar where direct path and…

Signal Processing · Electrical Eng. & Systems 2018-05-07 Yicheng Chen , Rick S. Blum

The waveforms of attosecond pulses produced by high-harmonic generation carry information on the electronic structure and dynamics in atomic and molecular systems. Current methods for the temporal characterization of such pulses have…

Attosecond streaking camera is an ex situ technique in which a linearly polarized (LP) XUV attopulse produces an electron wavepacket by photoionization in the presence of an IR femtopulse. By moving the two synchronous oppositely circularly…

Atomic Physics · Physics 2025-11-27 M. A. H. B. Md Yusoff , H. B. Ambalampitiya , J. M. Ngoko Djiokap

Analytic solutions to the time-dependent Schr\"odinger equation for cutoff wave initial conditions are used to investigate the time evolution of the transmitted probability density for tunneling. For a broad range of values of the potential…

Quantum Physics · Physics 2009-11-07 Gaston Garcia-Calderon , Jorge Villavicencio

The Eisenbud-Wigner-Smith (EWS) time delay of photoemission depends on the phase term of the matrix element describing the transition. Because of an interference process between partial channels, the photoelectrons acquire a spin…

Mesoscale and Nanoscale Physics · Physics 2018-12-12 Mauro Fanciulli , J. Hugo Dil

The use of few-femtosecond, extreme ultraviolet (XUV) pulses, produced by high-order harmonic generation, in combination with few-femtosecond infrared (IR) pulses in pump-probe experiments has great potential to disclose ultrafast dynamics…

Using a spectrally resolved electron interferometry technique, we measure photoionization time delays between the $3s$ and $3p$ subshells of argon over a large 34-eV energy range covering the Cooper minima in both subshells. The observed…

Photoionization as a half-scattering process is not instantaneous. Usually, time delays in photoionization are of the order of few tens of attoseconds (1 as = 10$^{-18}$ s). While going from a single atom to a nano-object, one can expect…

The time-integrated polarization degree (PD) at prompt optical band of gamma-ray burst (GRB) was predicted to be less than $20\%$, while the time-resolved one can reach as high as $75\%$ in photosphere model. Polarizations in optical band…

High Energy Astrophysical Phenomena · Physics 2024-05-13 Jia-Sheng Li , Mi-Xiang Lan , Hao-Bing Wang

We describe an ab initio and non-perturbative $R$-matrix with time-dependence theory for ultrafast atomic processes in light fields of arbitrary polarization. The theory is applicable to complex, multielectron atoms and atomic ions subject…

Atomic Physics · Physics 2018-12-04 D. D. A. Clarke , G. S. J. Armstrong , A. C. Brown , H. W. van der Hart

The evolution of electron wavepackets determines the course of many physical and chemical phenomena and attosecond spectroscopy aims to measure and control such dynamics in real-time. Here, we investigate radial electron wavepacket motion…

Atomic Physics · Physics 2015-09-04 Niranjan Shivaram , Xiao-Min Tong , Henry Timmers , Arvinder Sandhu

We demonstrate a two-dimensional time-domain spectroscopy method to extract amplitude and phase modifications of excited atomic states caused by the interaction with ultrashort laser pulses. The technique is based on Fourier analysis of the…

Atomic Physics · Physics 2015-06-19 Alexander Blättermann , Christian Ott , Andreas Kaldun , Thomas Ding , Thomas Pfeifer

We investigate electron momentum distributions from single ionization of Ar by two orthogonally polarized laser pulses of different color. The two-color scheme is used to experimentally control the interference between electron wave packets…

We present a theory of time-resolved photoionisation in the presence of a vortex beam. In a pump-probe setup, an extreme ultraviolet or an x-ray pump pulse triggers ionization, which is probed by a synchronized infrared pulse with non-zero…

Atomic Physics · Physics 2020-04-01 Sucharita Giri , Misha Ivanov , Gopal Dixit

The R-Matrix incorporating Time (RMT) method is a new method for solving the time-dependent Schroedinger equation for multi-electron atomic systems exposed to intense short-pulse laser light. We have employed the RMT method to investigate…

Atomic Physics · Physics 2012-04-27 L. R. Moore , M. A. Lysaght , J. S. Parker , H. W. van der Hart , K. T. Taylor

We present a method for handling view-dependent information in radiance fields to help with convergence and quality of 3D reconstruction. Radiance fields with view-dependence suffers from the so called shape-radiance ambiguity, which can…

Computer Vision and Pattern Recognition · Computer Science 2022-03-04 Sverker Rasmuson , Erik Sintorn , Ulf Assarsson

We investigate how a constant time delay influences a parametric autoresonant system. This is a nonlinear system driven by a parametrically chirped force with a negative delay-feedback that maintains adiabatic phase locking with the driving…

Chaotic Dynamics · Physics 2025-02-04 Somnath Roy , Mattia Coccolo , Miguel A. F. Sanjuán

We explore theoretically the navigation of an active particle based on delayed feedback control. The delayed feedback enters in our expression for the particle orientation which, for an active particle, determines (up to noise) the…

Statistical Mechanics · Physics 2019-07-24 S. M. J. Khadem , Sabine H. L. Klapp

We study resonant two-photon ionization of helium atoms via the $1s3p$, $1s4p$ and $1s5p^1$P$_1$ states using the 15$^\mathrm{th}$ harmonic of a titanium-sapphire laser for the excitation and a weak fraction of the laser field for the…

Spectra of circularly polarized harmonics is calculated by numerically solving the Time-Dependent Schr\"{o}dinger Equation for a 2D model of Ne atom using circularly polarized fundamental with counter-rotating second harmonic laser fields.…

Atomic Physics · Physics 2015-10-28 Lukas Medišauskas , Jack Wragg , Hugo van der Haart , Misha Yu. Ivanov