arXiv subjects

Vipul Badhan

Publications and source records attributed to Vipul Badhan.

4 recordsLinked to original sources

arXiv2026

A Standard Quantum Mechanical Treatment to Rationalize the Delayed-Choice Quantum Eraser

Ever since the proposal of delayed choice quantum erasure and subsequent realization in the experiment by Kim et al., the interpretation and implications of delayed-choice experiments have remained a subject of intense foundational debate. This paper resolves the apparent paradox attached to the experiment using standard quantum mechanics. Using an extended Mach-Zehnder interferometer which captures every operational feature of the original experiment, we show that choosing between which-path and erasure detectors is simply a choice of measurement bases, which does not rewrite a photon's past. Furthermore, by mapping the experiment to a two-way Stern-Gerlach framework, we prove that quantum erasure is an expected result of measuring entangled states, not a physical anomaly. Ultimately, through a pedagogical game, we illustrate that the illusion of retrocausality arises from asking illegitimate questions, and that a forward-in-time description is entirely sufficient to explain the logic.

quant-ph↗

arXiv2026

B-Spline for Self-Consistent Field Theory with a Z-Dependent Pauli Potential for Atomic Binding Energies

Polymer self-consistent field theory (SCFT) has recently been established as a promising alternative framework to Kohn-Sham density functional theory (KS-DFT) for modeling quantum many-body systems. It uses real-valued propagators instead of orbitals, simplifying the self-consistent numerical solution. However, SCFT suffers from inaccuracies in heavy-element systems due to the approximate treatment of the Pauli potential, particularly the use of a constant repulsion strength parameter. In this work, we address this central limitation by introducing a Z-dependent Pauli potential that improves agreement with Hartree-Fock (HF) results. Furthermore, we advance SCFT implementation by employing B-spline basis functions-highly localized, piecewise-polynomial functions widely used in atomic structure theory. We demonstrate that B-splines provide a flexible and efficient representation of electronic structure, and present results for atomic binding energies from hydrogen to xenon. Comparisons with HF theory and prior SCFT calculations using Gaussian basis sets highlight the improved accuracy achieved with the Z-dependent potential.

physics.chem-ph↗

arXiv2025

Portal for High-Precision Atomic Data and Computation

We've developed a scalable and sustainable online atomic data portal with an automated interface for easy update and addition of new data. The current portal provides energies, transition matrix elements, transition rates, radiative lifetimes, branching ratios, polarizabilities, hyperfine constants, and other data, for 28 atoms and ions. It also features an interactive polarizability plotting interface for neutral atoms and singly-charged ions. The data production is supported by recent developments of open-access atomic software based on our research codes, including new workflow algorithms, which allow large volumes of such data to be generated with automated accuracy assessments. This entails a new method of comparing our calculated values with data from the NIST Atomic Spectra Database. All calculated values include estimated uncertainties. Data for more systems will be added in the future. Experimental values are included with references, where high-precision data are available.

physics.atom-ph↗

arXiv2023

Accurate estimate of $C_5$ dispersion coefficients of the alkali atoms interacting with different material media

By inferring the dynamic permittivity of different material media from the observations and calculating dynamic electric dipole polarizabilties of the Li through Cs alkali atoms, precise values of $C_3$ coefficients were estimated in Phys. Rev. A {\bf 89}, 022511 (2014) and Phys. Lett. A {\bf 380}, 3366 (2016). Since significant contribution towards the long range van der Waals potential is given by the quadrupole polarization effects, we have estimated the $C_5$ coefficients in this work arising from the quadrupole polarization effects of all the alkali atoms interacting with metal (Au), semiconductor (Si) and four dielectric materials (SiO$_2$, SiN$_x$, YAG and sapphire). The required dynamic electric quadrupole (E2) polarizabilities are evaluated by calculating E2 matrix elements of a large number of transitions in the alkali atoms by employing a relativistic coupled-cluster method. Our finding shows that contributions from the $C_5$ coefficients to the atom-wall interaction potentials are pronounced at short distances (1$-$10 nm). The $C_3$ coefficients of Fr atom interacting with the above material media are also reported. These results can be useful in understanding the interactions of alkali atoms trapped in different material bodies during the high-precision measurements.

physics.atom-ph↗