arXiv subjects

R. Ahl Laamara

Publications and source records attributed to R. Ahl Laamara.

At least 19 recordsLinked to original sources

arXiv2026

Optics and Thermodynamics of Charged BTZ Black Holes with Exotic Matter Sources

We study a modified charged BTZ black hole in $(2+1)$--dimensional anti-de Sitter spacetime, where the standard geometry is surrounded by quintessence-like anisotropic matter and a cloud of strings. The corresponding metric function incorporates the effects of the electric charge and the two matter sources. The optical analysis reveals that their combined influence gives rise to a stable circular photon orbit, leading to distinctive modifications of photon dynamics and the associated energy emission. The thermodynamic analysis in a finite cavity further shows that the electric charge and exotic matter sources significantly affect the local thermal stability and phase structure of the black hole. The combined effects of these matter sources give rise to a stable photon sphere and novel thermodynamic behavior absent in the standard charged BTZ solution.

hep-th↗

arXiv2026

Quantumness of hybrid systems under quantum noise

We investigate the quantum correlations in an axially symmetric hybrid qubit-qutrit system subjected to different noisy environments. We first introduce a physical model and analyze its Hamiltonian structure, emphasizing the role of hybrid dimensionality and axial symmetry. The effects of decoherence are then examined under two local noise mechanisms, namely dephasing and phase-flip channels, acting on the qubit and qutrit subsystems in both symmetric and asymmetric configurations. Quantum correlations are quantified using negativity to capture entanglement and quantum discord based on linear entropy to characterize more general nonclassical correlations. Our results show that both thermal fluctuations and phase noise lead to a monotonic degradation of quantum correlations, with increasing temperature accelerating coherence loss and inducing entanglement sudden death at finite temperatures. While negativity vanishes abruptly under sufficiently strong noise, quantum discord persists beyond the entanglement threshold, revealing residual quantum correlations in mixed states. We further demonstrate that asymmetric noise configurations significantly enhance the robustness of both entanglement and discord by partially shielding coherence in the less affected subsystem. A comparative analysis reveals that phase-flip noise is more destructive than pure dephasing, leading to faster suppression of quantum correlations.

quant-ph↗

arXiv2026

Compactified 2HDM under the Non-SUSY AdS instability conjecture

We investigate how extra-dimensional dynamics influence Higgs-sector phenomenology by compactifying a Two-Higgs-Doublet Model (2HDM) coupled to 4D gravity on a circle $S^1$. The resulting effective potential includes tree-level 2HDM interactions, one-loop Coleman--Weinberg corrections from the Kaluza--Klein towers, and an effective radion stabilization contribution inspired by the broader modulus-stabilization literature. We derive the corresponding 3D effective action and show that, for the observed Higgs mass $m_h=125\,\mathrm{GeV}$, the compactified potential admits a stabilized configuration with near-zero vacuum energy. By imposing the non-supersymmetric AdS instability conjecture as a quantum-gravity consistency requirement, we obtain a constraint within our numerical setup on the heavy Higgs sector, finding that the additional scalar states must satisfy approximately $M_H \gtrsim 680\,\mathrm{GeV}$ in order to avoid perturbatively stable non-supersymmetric AdS$_3$ minima. Our results demonstrate how Swampland-inspired constraints can yield phenomenologically relevant predictions for extended Higgs sectors.

hep-ph↗

arXiv2026

Kerr-induced nonreciprocal transparency and group delay in a hybrid cavity magnomechanical system

We propose a scheme for realizing nonreciprocal transparency, Fano resonances, and slow/fast light in a hybrid cavity magnomechanical system containing two YIG spheres and a mechanical resonator. The nonreciprocal behavior originates from the magnon Kerr nonlinearity, which induces direction-dependent frequency shifts and modifies the interference pathways among cavity photons, magnons, and phonons. We show that the hybrid system supports multiple transparency windows arising from magnon- and magnomechanical-induced interference processes. The Kerr interaction strongly reshapes these transparency features, producing asymmetric Fano resonance line shapes and enabling controllable nonreciprocal transmission. Furthermore, the associated dispersion exhibits pronounced directional asymmetry, leading to giant differences in the group delay for opposite propagation directions and allowing reversible switching between slow- and fast-light regimes. We investigate the roles of hybrid coupling strengths and dissipation channels and identify parameter regimes where the nonreciprocal response is maximized. These findings establish Kerr-engineered magnomechanical systems as promising platforms for integrated nonreciprocal microwave photonics and quantum information technologies.

quant-ph↗

arXiv2026

A Swampland-modified Hod bound for charged black holes with exotic matter

In this paper, we study the quasinormal modes (QNMs) of a charged black hole in the presence of both quintessence and a cloud of strings using the Pade-averaged higher-order WKB approximation method. We investigate the effect of the quintessence parameter $α$ and the cloud of strings parameter $λ$ on the stability as well as the oscillation frequency of perturbations. The validity of Hod's conjecture, which relates quasinormal frequencies to the black hole temperature, is tested throughout the physically allowed parameter space. Our results show that both the effective potential and the decay rate of perturbations depend on the values of $α$ and $λ$, leading to either enhancement or suppression of the conditions required to satisfy Hod's bound. Furthermore, we discuss how these parameters modify the black hole shadow and the corresponding energy emission rate, revealing correlations with observable signatures. Finally, we establish a connection with the Swampland Distance Conjecture by expressing the Hawking temperature in terms of the scalar field excursion. Our analysis leads to a modified Hod bound and identifies a region of parameter space in which both the modified Hod bound and the Swampland constraints are simultaneously satisfied, ensuring consistency between black hole thermodynamics, observational properties, and quantum gravity constraints.

hep-th↗

arXiv2025

Swampland bound on quintessential inflation in IDM

We study a quintessential inflation scenario based on the Inert Doublet Model (IDM) coupled to a quintessence field via an exponential potential $V_0e^{-βϕ/M_p}$. Using a conformal transformation from the Jordan frame to the Einstein frame, we derive an effective Starobinsky-type potential modulated by an exponential factor that naturally unifies the inflationary epoch with the late-time accelerated expansion of the Universe. We analyze the resulting two-field dynamics, compute the slow-roll parameters, the primordial perturbation spectrum, as well as the inflationary observables $n_s$ and $r$, and then confront the predictions with the latest $Planck$ and $BICEP/Keck$ data. We find amongst others that the quintessence inflaton coupling must remain extremely weak, in the order of $β\lesssim 4\times10^{-3}$, to satisfy current $CMB$ data, whereas swampland dS conjecture favors a step potential with $β\sim\mathcal{O}(1)$, signaling a significant tension between quantum gravity consistency and cosmological viability. We conclude by discussing possible extensions and stabilization mechanisms that could help reconcile the inflationary predictions with swampland constraints.

hep-ph↗

arXiv2025

Topological Properties of Bilayer $α-T_{3}$ Lattice Induced by Polarized Light

We investigate the topological properties of photon-dressed energy bands in bilayer $α-T_{3}$ lattices under off-resonant circularly polarized light, focusing on aligned and cyclic stacking configurations. Analytical expressions for quasi-energy bands are derived for aligned stacking, while numerical results address cyclic stacking at Dirac points. Circularly polarized light breaks the time-reversal symmetry, lifting the degeneracies at the intersections $t^{a,c}$, leading to the appearance of a Haldane-type Chern insulator in the absence of a magnetic field . At $α= 1/\sqrt{2}$, orbital magnetic moments of corrugated and flat bands exhibit opposite signs, as do their Berry curvatures. For $0 < α< 1$, light-induced band deformations near Dirac points create gaps in the quasi-energy spectrum, where the chemical potential modulates orbital magnetization. Linear magnetization variations align with Chern numbers, yielding quantized anomalous Hall conductivity across stacking types. Notable particle-hole symmetry breaking within $0 < α< 1$ suggests applications in valley caloritronics and quantum sensing. At $α= 1$, flat and corrugated bands remain undistorted; while the flat band contributes no Berry curvature, it produces a finite negative orbital magnetic moment, contrasting with the positive moment of the corrugated band.

cond-mat.mes-hall↗

arXiv2025

Quantum Phase Sensitivity with Generalized Coherent States Based on Deformed su(1,1) and Heisenberg Algebras

We investigate the phase sensitivity of a Mach-Zehnder interferometer using a special class of generalized coherent states constructed from generalized Heisenberg and deformed $su(1,1)$ algebras. These states, derived from a perturbed harmonic oscillator with a four parameter deformed spectrum, provide enhanced tunability and nonclassical features. The quantum Fisher information and its associated quantum Cramer-Rao bound are computed to define the fundamental precision limits in phase estimation. We analyze the phase sensitivity under three realistic detection methods: difference intensity detection, single mode intensity detection, and balanced homodyne detection. The performance of each method is compared with the quantum Cramer Rao bound to evaluate their optimality. Our results demonstrate that, for suitable parameter regimes, these generalized coherent states enable phase sensitivities approaching the quantum limit. This offers a flexible framework for precision quantum metrology and potential applications in quantum enhanced sensing.

quant-ph↗

arXiv2025

Landscape of Narain CFTs

In this work, we investigate the AdS$_{3}$ gravitational bulk dual to an ensemble of Narain CFTs and their generalisations to establish bounds consistent with the Swampland program. Focusing on the AdS distance and finiteness conjectures, we show that the central charge of Narain CFTs forming the ensemble must be finite. Combining anomaly and unitary requirements, we derive an upper bound on the rank of the abelian U(1) gauge symmetries that can consistently couple to the AdS$_{3}$ gravity. We give explicit realisations of these constraints by determining the range of the Chern-Simons level $k^{G}$ corresponding to a bounded AdS$_{3}$ radius$.$ Accordingly, the Narain landscape is finite with a number of admissible CFTs constrained as $3/2\lesssim c\lesssim 10^{3}.$

hep-th↗

arXiv2025

Optimizing Multi-Hop Quantum Communication using Bidirectional Quantum Teleportation Protocol

In this paper, we introduce a new method for Bidirectional Quantum Teleportation called Bidirectional Quantum Teleportation using the Modified Dijkstra Algorithm and Quantum Walk (BQT-MDQW). This method uses different types of entangled states, such as the GHZ-Bell state, W-Bell state, and Cluster-Bell state, to improve quantum communication in multi-hop quantum wireless networks. We focus on the W-Bell state and compare the quantum Dijkstra algorithm with the classical Dijkstra method to see which one works better. We apply both versions to quantum and classical simulators, measuring their performance through fidelity, memory utilization, and throughput calculations. Our results show that the shortest path problem may be solved with significantly reduced computer complexity using the quantum Dijkstra algorithm based on quantum walks. The introduction of a quantum walk, which permits dynamic transitions between quantum channels and the effective exploration of quantum network states, is an important part of the protocol. Using the capacity of the quantum walk to adjust to changing quantum states, we also introduce a method for successfully identifying unitary matrices under varying quantum channels. The bidirectional teleportation structure of the protocol is designed to solve the multi-hop teleportation problem in quantum wireless networks. In addition, we present quantum Dijkstra's algorithm, which uses quantum gates to significantly decrease computational complexity and solve the networking problem by building on the quantum walk framework. This method shows how quantum computing may be used to solve arbitrary optimization issues such as the shortest path problem. Finally, we present a novel multi-hop quantum teleportation system encompassing both unidirectional and bidirectional communication, as introduced in the quantum Dijkstra algorithm system...

quant-ph↗

arXiv2025

Black hole solutions of three dimensional E$_{6}$-gravity

This paper aims to construct exceptional Banados-Teitelboim-Zanelli (BTZ) black holes carrying E$_{6}$ charges as solutions to the 3D higher spin Anti-de Sitter (AdS) gravity with E$_{6}$ boundary conditions. Guided by Tits-Satake graphs of real forms of the e$_{6} $ Lie algebra, we build three remarkable E$_{6}$-higher spin black hole models: the linear-exceptional and the ortho-exceptional BTZ solutions result from splitting the extremal nodes in the E$_{6\left( 6\right)}$ Tits-Satake diagram while the pure exceptional-exceptional model follows from the folding down to F$_{4\left( 4\right) }$. And with the help of Hasse diagram visualizations, we study the ensuing higher spin spectrums to develop the corresponding metrics using two types of gauge transformations. For completeness, we examine the thermodynamics of the standard BTZ coupled to E$_{6}$ higher spin gravity fields by computing the partition function exploiting a one to one correspondence between the factors of the vacuum characters and the roots of the E$_{6}$ root system.

hep-th↗

arXiv2025

Fluctuating Ensemble Averages and the BTZ Threshold

Recent work shows fascinating links between ensemble averaging and the Swampland program. In order to break the emerging global symmetries of the ensemble averaging as dictated by the no global symmetries conjecture, one may consider fluctuations away from the average given by deviations in the Siegel-Weil formula. In this work, we investigate the physical interpretation of these fluctuations in the bulk physics and pinpoint the states giving rise to them. For this purpose, we explore an ensemble of generalised Narain CFTs and build the AdS$_{3}$ gravitational dual in the Chern-Simons (CS) framework. We study the associated charged BTZ black hole solution and assess its stability. Using the Swampland weak gravity conjecture, we show that the fluctuations of the ensemble average are below the BTZ threshold and correspond to a sublattice of superextremal states emitted by the black hole. We exploit the logarithmic density of states to derive bounds on the charged vectors of the abelian CS symmetry and introduce a novel formulation of the density function to ensure consistency with the sublattice WGC. We establish bounds that allows to distinguish heavy states contributing to the average from light states generating fluctuations around it.

hep-th↗

arXiv2024

Dynamic Evolution of Quantum Fisher and Skew Information under Decoherence in Three-Qubit X-States

Quantum metrology leverages quantum effects such as squeezing, entanglement, and other quantum correlations to boost precision in parameter estimation by saturating quantum Cramer Rao bound, which can be achieved by optimizing quantum Fisher information or Wigner-Yanase skew information. This work provides analytical expressions for quantum Fisher and skew information in a general three-qubit X-state and examines their evolution under phase damping, depolarization, and phase-flip decoherence channels. To illustrate the validity of our method, we investigate their dynamics for a three-qubit Greenberger-Horne-Zeilinger (GHZ) state subjected to various memoryless decoherence channels. Closed-form expressions for QFI and SQI are derived for each channel. By comparing these metrics with the entanglement measure of concurrence, we demonstrate the impact of decoherence on measurement precision for quantum metrology. Our results indicate that phase damping and phase-flip channels generally allow for better parameter estimation compared to depolarization. This study provides insights into the optimal selection of noise channels for enhancing precision in quantum metrological tasks involving multi-qubit entangled states.

quant-ph↗

arXiv2024

Finiteness of 3D higher spin gravity Landscape

We give Swampland constraints on the three dimensional Landscape of Anti-de Sitter higher spin gravity in the Chern-Simons formulation with connection valued in various split real forms of Lie algebras. We derive the finiteness conjecture by computing the upper bound on the rank of possible gauge groups then we refine it using the AdS distance conjecture. We discuss the implications of this Swampland constraint on the spectrum of higher spin gravity theories and we compare it with the gravitational exclusion principle required from BTZ black hole consideration to excerpt a constraint on the Chern-Simons level k.

hep-th↗

arXiv2024

Effects of DM and KSEA interactions on entanglement, Fisher and Wigner-Yanase information correlations of two XYZ-Heisenberg-qubit states under a magnetic field

We employ entanglement negativity, local quantum uncertainty (LQU), and local quantum Fisher information (LQFI) to characterize thermal entanglement between two XYZ-Heisenberg-qubit states under the influence of Dzyaloshinsky Moriya (DM) and Kaplan Shekhtman Entin Wohlman Aharony (KSEA) interactions, as well as a magnetic field and thermal equilibrium temperature. A comparative examination reveals similar behaviors among these correlation measures. For the antiferromagnetic scenario, we observe that increasing the DM interaction parameter Dz enhances thermal entanglement. Conversely, in the ferromagnetic case, the behavior of thermal entanglement differs with varying Dz. Additionally, employing Kraus operators, we explore the performance of these quantifiers under decoherence. Notably, LQFI exhibits greater robustness than negativity and LQU, even displaying a frozen phenomenon at some time under dephasing effects.

quant-ph↗

arXiv2024

Cyclic Quantum Teleportation of Two-Qubit Entangled States by using Six-Qubit Cluster State and Six-Qubit Entangled State

Cyclic quantum teleportation schemes requires at least the existence of three collaborators acting all as senders and receivers of quantum information, each one of them has an information to be transmitted to the next neighbour in a circular manner. Here, new cyclic quantum teleportation scheme is proposed for perfectly transmitting cyclically three arbitrary unknown two-qubit states ($α$, $β$ and $γ$) among the three collaborators. In this scheme, Alice can send to Bob the quantum information contained in her two-qubit state $α$ and receive from Charlie the quantum information contained in the two-qubit state in his possession $γ$ and similarly, Bob can transmit to Charlie the quantum information contained in his two-qubit state $β$ through a quantum channel of twelve-qubit state consisting of a six-qubit cluster state and a six-qubit entangled state by sequentially and cyclically performing Bell state measurements. Subsequently, each one of the three participants can afterwards retrieve his own desired two-qubit state using classical channel and by performing appropriate unitary Pauli operators and we have shown that our proposed scheme performs efficiently.

quant-ph↗

arXiv2024

Asymptotic Weak Gravity Conjecture in M-theory on K3 $\times$ K3

The Asymptotic WGC has been proposed as a special case of the tower WGC that probes infinite distances in the moduli space corresponding to weakly coupled gauge regimes. The conjecture has been studied in M-theory on Calabi-Yau threefold (CY3) with finite volume inducing a 5D effective QFT. In this paper, we extend the scope of the previous study to encompass lower dimensions, particularly we generalise the obtained 5D asymptotic WGC to the effective field theory $EFT_{3D}$ coupled to 3D gravity that descends from M-theory compactified on Calabi-Yau fourfold with an emphasis on K3 x K3. We find that the CY4 has three fibration structures labelled as line Type-$T^2$, surface Type-$S$ and bulk Type-$V$. The emergent $EFT_{3D}$ is shown to have 2+2 towers of states occupied by light and heavy BPS as well as non BPS particles. To ensure the viability of the 3D Asymptotic WGC, we give explicit calculations to thoroughly test the swampland constraint for both the weakly and strongly gauge coupled regimes. Additional aspects, including the gauge symmetry breaking and duality symmetry are also investigated.

hep-th↗

arXiv2023

The electronic, thermodynamic, thermoelectric and optical properties of Ca(InP)2 compound: DFT study

In this study, we investigate the electronic, optical, thermoelectric, and thermodynamic properties of Ca(InP)2 through comprehensive theoretical calculations Ca(InP)2 is a compound with promising applications in materials science and electronics. Using the density functional theory (DFT) with Generalized Gradient Approximation (GGA) and modified Becke_Johnson approximation (mBJ), we determine the band structure, density of states, and optical properties of Ca(InP)2. The obtained results reveal that the Ca(InP)2 compound exhibits a direct band gap of 0 eV and 0,645 eV for PBE-GGA and GGA+mBJ, respectively. This direct band gap is found at the Gamma point of the Brillouin zone, making it well-suited for optoelectronic applications. Furthermore, we analyze the thermoelectric properties such as the Seebeck coefficient, the lattice thermal conductivity, and optical properties like dielectric function, absorption coefficient, conductivity, and extinction coefficient. Thermodynamic properties, including heat capacity and Debye temperature, are also calculated, providing a deeper understanding of the compound's thermal behavior. The findings of this study highlight the fundamental characteristics of Ca(InP)2 and offer valuable information for its potential use in electronic and optoelectronic devices. A comprehensive understanding of the electronic, optical, and thermodynamic properties of the Ca(InP)2 compound can serve as a guide for future experimental research and aid in the design of novel materials for a wide range of technological applications.

cond-mat.mtrl-sci↗