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Amol R Holkundkar

Publications and source records attributed to Amol R Holkundkar.

3 recordsLinked to original sources

Relativistic electron dynamics in ultra-intense lasers

These lectures at Winter School on Intense Laser Science (WiSILS-2024) at IIT Jodhpur, India, will focus on the Relativistic charge particle dynamics in ultra-intense laser pulses. We will be learning about the relativistic equations of motion, Radiation-Reaction, Thomson scattering, Ponderomotive scattering, and its usage as the potential diagnostic tool. A simulation code LEADS will address the relativistic electron dynamics in the intense-laser pulse.

physics.plasm-ph↗

Phase-Controlled Ramsey Interference of XUV Photoelectrons

We investigate Ramsey-type quantum interference in photoelectron momentum distributions generated by two time-delayed, linearly polarized extreme-ultraviolet (XUV) laser pulses. The electron dynamics are studied by solving the full-dimensional time-dependent Schrödinger equation within the single-active-electron approximation for neon initially prepared in a current-carrying $2p_+$ state. The coherent superposition of electron wave packets released by the two pulses gives rise to pronounced interference fringes in both energy-resolved spectra and angle-resolved momentum distributions. We demonstrate that the fringe positions are governed by a Ramsey phase accumulated during the interpulse delay, resulting in a linear dependence on the relative carrier-envelope phase and an inverse scaling of the fringe spacing with the delay time. By systematically varying the laser intensity, we establish that the observed modulations originate from temporal quantum interference rather than Autler--Townes splitting. Analysis of the time-resolved bound-state population dynamics reveals that carrier-envelope-phase dependent bound--bound coupling dominated by transient population transfer to the $2s$ state, which controls the interference contrast. The accumulated phase is further interpreted in terms of a dynamic Stark shift of the dressed bound states, which is quantitatively reproduced using a reduced two-level model.

physics.atom-ph↗

Temporal control of high-order harmonic cutoffs in periodic crystals

A theoretical study on the high-harmonic generation (HHG) in solids by a synthesized driver field is carried out. The vector potential of the driver field is instrumental in determining the Bloch oscillations of the electrons in a periodic crystal, which eventually reflects in the high-order harmonic spectra. To this end, the interaction of the sinc-shaped driver with the periodic crystal is studied. A typical temporal profile of the associated vector potential manifests in extending the harmonic cutoffs compared to the standard sin$^2$ envelopes of similar intensity and duration. It is also observed that the harmonic cutoffs can be controlled in a temporal manner by varying the delay parameter introduced in the proposed sinc-shaped driver, with a well-defined scaling that depends on the energy bands of the periodic crystal under study. Furthermore, it is also observed that the emission time of the cutoff harmonics and even the harmonic cutoff energy can also be controlled by varying the delay parameter systematically. An optimum delay parameter for maximum harmonic cutoff energy and harmonic yield is also deduced.

physics.atm-clus↗