arXiv subjects

Neha Kukreti

Publications and source records attributed to Neha Kukreti.

3 recordsLinked to original sources

arXiv2026

Coherent control of orthogonal continuum states in XUV photoionization

We demonstrate coherent control of orthogonal continuum electron states in the XUV photoionization of atomic hydrogen using polarization-tailored driving fields. By combining polarization mixing with carrier-envelope-phase (CEP) control, we generate a pair of orthogonal momentum-space basis states whose populations and relative phase can be independently tuned via the polarization-mixing parameter and CEP, respectively. The resulting photoelectron wave packets are prepared as coherent superpositions within this effective two-dimensional subspace, with quantum coherence confirmed by interference visibilities reaching 99% in the photoelectron momentum distributions (PMDs). We further demonstrate that a bichromatic driving-field configuration extends this framework to a four-dimensional continuum manifold, with basis states distinguished by both angular emission patterns and radial momentum distributions, and with independent amplitude and phase control preserved across the higher-dimensional subspace. These results establish that polarization-tailored XUV fields provide a flexible route to independent amplitude and phase control within low-dimensional subspaces of the photoelectron continuum, with the engineered dynamics directly observable in momentum-resolved spectra.

physics.atom-ph↗

arXiv2026

Wavelength-driven photoelectron momentum tilt in XUV Ionization

We investigate how atomic structure influences photoelectron momentum distributions (PMDs) in single-photon ionization by a linearly polarized extreme-ultraviolet (XUV) pulse. We demonstrate that the PMD tilt is governed not only by the magnetic quantum number but also by the radial structure of the bound atomic orbital. While neon exhibits a smooth wavelength dependence of the PMD tilt, argon displays a non-monotonic behavior characterized by suppression and reversal of the tilt at a critical wavelength. A partial-wave analysis reveals that this behavior arises from interference between $s$- and $d$-wave channels, with the reversal originating from a minimum in the $d$-wave radial dipole matrix element induced by the radial node in the argon 3p orbital. We further show that atomic interferometric circular dichroism (AICD) serves as a sensitive probe of this effect. These findings establish a direct link between the radial wavefunction structure and observable momentum-space asymmetries, highlighting the wavelength-dependent rotation and the suppression of the PMD tilt as signatures of radial-node-induced Cooper-like suppression in the $d$-wave channel of argon.

physics.atom-ph↗

arXiv2026

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 Schr\"odinger 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↗