arXiv subjects

Bhargab Das

Publications and source records attributed to Bhargab Das.

4 recordsLinked to original sources

arXiv2025

(Algebraic) $ p $-adic Artin formalism of twisted triple product Galois representations over real quadratic fields

In this article, we investigate factorization problems for twisted triple product Galois representations over real quadratic fields, arising from families of Hilbert cusp forms. Specifically, we address the factorization in two distinct settings determined by the order of vanishing of associated $L$-unctions at their central critical values-namely, the rank (1,1) and rank (0,2) cases. Our results generalize the algebraic factorization framework developed by B\"{u}y\"{u}kboduk et al. in higher rank scenario to the setting of real quadratic fields. Notably, our work yields the first known factorization result in the higher rank (0,2) case, marking a significant advancement in the study of triple product motives over totally real fields.

math.NT↗

arXiv2022

Ghost diffraction: A spatial statistical approach

We report the reconstruction of a transparency image in Ghost diffraction scheme using a statistical optics approach. This is implemented by using a static diffuser rather than a pseudo thermal light source with a rotating diffuser. The experimental implementation makes use of spatial ergodicity and spatial stationarity for spatially distributed random fields. A strategy to realize the Ghost diffraction scheme through spatial intensity correlation with a phase retrieval algorithm permits reconstruction of the transparency.

physics.optics↗

arXiv2017

Pico-strain-level dynamic perturbation measurement using πFBG sensor

Interferometric interrogation technique realized for conventional fiber Bragg grating (FBG) sensors is historically known to offer the highest sensitivity measurements, however, it has not been yet explored for π-phase-shifted FBG (πFBG) sensors. This, we believe, is due to the complex nature of the reflection/transmission spectrum of a πFBG, which cannot be directly used for interferometric interrogation purpose. Therefore, we propose here an innovative as well as simple concept towards this direction, wherein, the transmission spectrum of a πFBG sensor is optically filtered using a specially designed fiber grating. The resulting filtered spectrum retains the entire characteristics of a πFBG sensor and hence the filtered spectrum can be interrogated with interferometric principles. Furthermore, due to the extremely narrow transmission notch of a πFBG sensor, a fiber interferometer can be realized with significantly longer path difference. This leads to substantially enhanced detection limit as compared to sensors based on a regular FBG of similar length. Theoretical analysis demonstrate that high resolution weak dynamic strain measurement down to 4 pε/sqrt(Hz) is easily achievable.

physics.ins-det↗

arXiv2015

Non-invasive single-shot 3D imaging through a scattering layer using speckle interferometry

Optical imaging through complex scattering media is one of the major technical challenges with important applications in many research fields, ranging from biomedical imaging, astronomical telescopy, and spatially multiplex optical communications. Although various approaches for imaging though turbid layer have been recently proposed, they had been limited to two-dimensional imaging. Here we propose and experimentally demonstrate an approach for three-dimensional single-shot imaging of objects hidden behind an opaque scattering layer. We demonstrate that under suitable conditions, it is possible to perform the 3D imaging to reconstruct the complex amplitude of objects situated at different depths.

physics.optics↗