arXiv subjects

Syed Masood

Publications and source records attributed to Syed Masood.

11 recordsLinked to original sources

arXiv2026

Quantum-inspired Topographic Stereovision

We revisit the conventional triangulation in distant stereovision, when shape rather than distance is the relevant observable. We show through the information-regret analysis that the optimal measurements for absolute distance and relative topography are unexpectedly different and incompatible, exposing an observable-measurement mismatch. To resolve this, we introduce stereo regularization to address stereo anisotropies that violate prevailing emitter-number conservation. Accordingly, we propose a topographic interferometer, which exploits cross-detector correlations to probe topography without measuring the distance profile. Our Fizeau-imaging interferometer turns parallax paths into Mach-Zehnder arms and employs a central path as the local oscillator for balanced homodyne detection, saturating the quantum Fisher information with improved topographic error scaling. This enables topographic stereovision of thermal sources beyond the Rayleigh limit, with feasible experimental demonstrations within existing techniques for remote sensing and astronomy.

quant-ph↗

arXiv2025

Acceleration radiation from vibrating atoms in Schwarzschild spacetime

Motivated by the work of Scully \textit{et al.} [ \textcolor{blue}{Proc. Nat. Acad. Sci. 115, 8131 (2018)}] and Dolan \textit{et al.}[ \textcolor{blue}{New J. Phys. 22, 033026 (2020)}], we study the acceleration radiation from a two-level Unruh-DeWitt detector that undergoes small-amplitude radial oscillations at fixed mean radius $R_0$ outside a Schwarzschild black hole. The massless scalar field is quantized in the Boulware vacuum to isolate curvature-modulated acceleration effects without a thermal Hawking background. Working in a (1+1) radial reduction and using first-order time-dependent perturbation, we evaluate the period-averaged transition rate (or the Floquet transition rate). The resulting particle emission spectrum exhibits a thermal Bose-Einstein-type profile with periodic trajectory yielding a Floquet resonance condition $n\Omega > \omega_0$ and a closed-form expression for the Floquet transition rate $\overline{P}_n$, which reduces to the flat Minkowski spacetime result as $R_0\to\infty$, in agreement with Near the horizon, $f(R_0)<1$ enhances the effective Bessel argument by $1/\sqrt{f(R_0)}$, providing a simple analytic demonstration of curvature/redshift amplification of acceleration radiation. In particular, the spectrum weighted by the Bessel function becomes ill-defined near the black hole horizon as $R_{0}\rightarrow 2M$, possibly manifesting the well-known pathological behavior of the Boulware vacuum state. We discuss the regime of validity (small amplitude, $R_0$ away from the horizon) and outline the extensions to (3+1) dimensions, including density-of-states and greybody factors, and to alternative vacuum choices. Our results offer an analytically tractable link between flat-space vibrating atom proposals and black-hole spacetimes.

gr-qc↗

arXiv2025

Quantum light and radiation in Rindler spacetime: from uncertainty relations to the cosmological implications

Based on an analogy between diffraction integral formalism of classical field propagation and Feynman path integral approach to quantum field theory, we develop a quantum model for light and radiation in Rindler spacetime. The framework helps to reveal acceleration-induced contributions to the traditional Heisenberg position-momentum uncertainty relation. A modified Planck energy density distribution of radiation is established and reveals equivalence between temperature and Rindler acceleration as advocated by standard Unruh and anti-Unruh effects. Later, by defining an equivalent acceleration, we investigate some cosmological implications of the model with regards to redshift and expansion of the Universe. In this context, we contend that the accelerated expansion of the Universe, in addition to possessing some well-defined limits corresponding to early and local Universe epochs, may also hint towards dynamical nature of dark energy. The findings provide glimpse into future table-top experiments aimed at emulating gravitational and other cosmological phenomena in terrestrial lab setups.

gr-qc↗

arXiv2024

The thermodynamic profile of AdS black holes in Lorentz-violating Bumblebee and Kalb-Ramond gravity

Lorentz invariance violation (LIV) is a topic of significant interest in quantum gravity and in extensions of the Standard Model of particle physics. Recently, new classes of black hole solutions have been proposed, involving vector fields and rank-two antisymmetric tensor fields that acquire nontrivial vacuum expectation values, resulting in the Bumblebee and Kalb-Ramond (KR) gravity models, respectively. These models exhibit novel geometric structures and differ in notable ways from standard Einstein gravity. In this study, we examine neutral anti-de Sitter (AdS) black holes within the context of LIV backgrounds, focusing on their thermodynamic properties through two distinct approaches. The first approach utilizes the free energy landscape framework, revealing substantial modifications to the conventional Hawking-Page phase transition. Specifically, LIV effects can alter the stability regimes of black holes and thermal AdS phases, potentially leading to overlapping thermodynamic regimes that would otherwise remain distinct. The second approach involves thermodynamic Ruppeiner geometry, which provides a window into the microstructure of black holes via a well-defined scalar curvature. In general, LIV effects are negligible for larger black holes, which behave like an ideal gas with no significant interactions among their constituents. However, at shorter length scales, the presence of LIV can induce multiple stable and unstable phase transitions, depending on the specific gravity model and the magnitude of LIV effects considered. While Bumblebee and Kalb-Ramond gravity share several similarities, we identify distinctive signatures arising from their underlying physical mechanisms. These differences may provide key observational and theoretical constraints for testing LIV effects in black hole physics.

gr-qc↗

arXiv2024

A Casimir-like probe for 4D Einstein-Gauss-Bonnet gravity

Virtual transitions in a Casimir-like configuration are utilized to probe quantum aspects of four-dimensional Einstein-Gauss-Bonnet (4D EGB) gravity. This study employs a quantum optics-based approach, wherein an Unruh-DeWitt detector (modeled as a two-level atom) follows a radial timelike geodesic, falling freely into an uncharged, nonrotating black hole described by 4D EGB gravity, becoming thermalized in the usual Unruh manner. The black hole, asymptotically Minkowskian, is enclosed by a Casimir boundary proximate to its horizon, serving as a source for accelerated field modes that interact with the infalling detector. Observations are conducted by an asymptotic infinity observer, assuming a Boulware field state. Our numerical analysis reveals that, unlike in Einstein gravity, black holes in 4D EGB gravity can either enhance or suppress the intensity of acceleration radiation, contingent upon the Gauss-Bonnet coupling parameter $\alpha$. Specifically, we observe radiation enhancement for negative $\alpha$ and suppression for positive $\alpha$. These findings offer substantial insights into quantifying the influence of higher-curvature contributions on the behavior of quantum fields in black hole geometries within a 4D spacetime.

gr-qc↗

arXiv2024

Short-distance thermal phase structure of charged black holes in 4D Einstein-Gauss-Bonnet gravity

Glavan and Lin's proposal of an effective four-dimensional Einstein--Gauss--Bonnet (4D-EGB) gravity framework yields predictions that differ from general relativity in some regimes. A range of black hole studies have offered insights into the dynamical and phenomenological aspects of this effective theory of gravity. In this work, the thermodynamics of a charged 4D-EGB black hole with Gauss--Bonnet (GB) coupling $\alpha$, characterized by mass $M$ and charge $Q$ in the non-extremal regime $M>\sqrt{Q^2+\alpha}$ is investigated by combining a non-perturbative, quantum-gravity-inspired exponential correction to the entropy (quantified by $\eta$) with information-geometric diagnostics. Within a canonical ensemble (fixed $Q$) paradigm, thermodynamic stability regions and phase-transition-like features are identified as the black hole size tends toward extremality due to Hawking evaporation. The Ruppeiner metric is then constructed on the $(M,Q)$ state space and the associated thermodynamic curvature is evaluated to characterize the effective interaction signatures and its relation to critical behavior. In addition, an effective quantum-work quantity, defined from the free-energy landscape using Jarzynski equality, is evaluated as an additional probe of short-distance, near-extremal behavior. The results indicate that departures from the general-relativistic behavior are negligible for large black holes but can become relevant at small horizon scales. Specifically, on short-distance scales, the combined influence of $\alpha$ and $\eta$ can modify stability of the extremal black hole geometry and remnants within this thermodynamic model.

gr-qc↗

arXiv2020

Rainbow Spacetime from a Nonlocal Gravitational Uncertainty Principle

Occurrence of spacetime singularities is one of the peculiar features of Einstein gravity, signalling limitation on probing short distances in spacetime. This alludes to the existence of a fundamental length scale in nature. On contrary, Heisenberg quantum uncertainty relation seems to allow for probing arbitrarily small length scales. To reconcile these two conflicting ideas in line with a well known framework of quantum gravity, several modifications of Heisenberg algebra have been proposed. However, it has been extensively argued that such a minimum length would introduce nonlocality in theories of quantum gravity. In this Letter, we analyze a previously proposed deformation of the Heisenberg algebra (i.e. $p \rightarrow p (1 + \lambda p^{-1})$) for a particle confined in a box subjected to a gravitational field. For the problem in hand, such deformation seems to yield an energy-dependent behavior of spacetime in a way consistent with gravity's rainbow, hence demonstrating a connection between non-locality and gravity's rainbow.

gr-qc↗

arXiv2020

The large scale structure formation in an expanding universe

In this paper, we analyze the effects of expansion on large scale structure formation in our Universe. We do that by incorporating a cosmological constant term in the gravitational partition function. This gravitational partition function with a cosmological constant is used for analyzing the thermodynamics of this system. We analyze the virial expansion for this system, and obtain its equation of state. It is observed that the generalization of this equation of state is like the Van der Waals equation. We also analyze a gravitational phase transition in this system using the mean field theory. We construct the cosmic energy equation for this system of galaxies, and discuss its consequences. We obtain and analyze the distribution function for this system, using the gravitational partition function. We also compare the results obtained in this paper with the observational data.

physics.gen-ph↗

arXiv2017

Non-Local Deformation of a Supersymmetric Field Theory

In this paper, we will analyse a supersymmetric field theory deformed by generalized uncertainty principle and Lifshitz scaling. It will be observed that this deformed supersymmetric field theory contains non-local fractional derivative terms. In order to construct such deformed N=1 supersymmetric theory, a harmonic extension of functions will be used. However, the supersymmetry will be only preserved for a free theory and will be broken by the inclusion of interaction terms.

hep-th↗

arXiv2017

Boundary Effects in Super-Yang-Mills Theory

In this paper, we shall analyse a three dimensional supersymmetry theory with $\mathcal{N} = 2$. The effective Lagrangian will be given by the sum of the gauge fixing term and the ghost term with the original classical Lagrangian. In presence of a boundary the supersymmetry of this Lagrangian will be broken. However, it will be possible to preserve half the supersymmetry even in presence of a boundary. This will be done by adding a boundary Lagrangian to the effective bulk Lagrangian. The supersymmetric transformation of this new boundary Lagrangian will exactly cancel the boundary term generated from the supersymmetric transformation of the effective bulk Lagrangian. We will obtain the Slavnov-Taylor Identity for this theory.

hep-th↗

arXiv2016

The Most General Form of Deformation of the Heisenberg Algebra from the Generalized Uncertainty Principle

In this paper, we will propose the most general form of the deformation of Heisenberg algebra motivated by the generalized uncertainty principle. This deformation of the Heisenberg algebra will deform all quantum mechanical systems. The form of the generalized uncertainty principle used to motivate these results will be motivated by space fractional quantum mechanics and non-locality in quantum mechanical systems. We also analyse a specific limit of this generalized deformation for one dimensional system, and in that limit, a nonlocal deformation of the momentum operator generates a local deformation of all one dimensional quantum mechanical systems. We analyse the low energy effects of this deformation on a harmonic oscillator, Landau levels, Lamb shift, and potential barrier. We also demonstrate that this deformation leads to a discretization of space.

hep-th↗