arXiv subjects

Seyed Mohsen Moosavi Khansari

Publications and source records attributed to Seyed Mohsen Moosavi Khansari.

10 recordsLinked to original sources

arXiv2026

Quantum Beam Splitter as a Deterministic Entanglement Source: Exact Photon-Number Statistics, Hong-Ou-Mandel Interference, and von Neumann Entropy Scaling from Balanced Inputs

In this work, we present a comprehensive analytical study of a lossless quantum beam splitter (BS) with transmission coefficient T and reflection coefficient R. Using the unitary operator representation and binomial expansion, we derive the exact probability distribution P_k for detecting k photons in one output port when the input ports are prepared in Fock states |N>_0 |M>_1. The balanced configuration R = T = 1/2 and N = M is examined in detail: we prove that destructive quantum interference suppresses all odd photon numbers at the outputs, leaving only even photon counts. The special case N = M = 1 reproduces the famous Hong-Ou-Mandel (HOM) dip with P_1 = 0. Beyond photon statistics, we demonstrate that the beam splitter functions as a deterministic, tunable source of photon-number entanglement. By tracing over one output mode, we construct the reduced density matrix rho_2 and compute the von Neumann entropy S = - sum_k P_k log2 P_k, a direct measure of entanglement between the two output ports. For the balanced case with N = M = 1, we obtain S = 1 ebit, i.e., maximal Bell-state entanglement. For larger equal photon numbers, the entropy increases monotonically. Our results transform the passive beam splitter into a deterministic source of photon-number entanglement, with direct applications in optical quantum computing, interferometry, and quantum information processing. Numerical three-dimensional plots of the probability distribution are provided, and all derivations are supported by rigorous algebra and a full appendix.

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arXiv2026

Hamiltonian-Generated Dynamics and Quantum Resource Allocation in a 4-Qubit Isotropic Heisenberg Spin Ring with Adjustable Next-Nearest-Neighbor Interactions

This investigation delivers a fully analytical solution for the unitary evolution of a four-qubit isotropic Heisenberg XXX ring with periodic boundary conditions and a tunable next-nearest-neighbor exchange parameter $α$. Adopting a Bell-type product state as the initial condition, we obtain closed-form expressions for the square-root fidelity $F(ρ(0),ρ(t))=|\cos(ϕ/2)|$, the global $l_1$-norm coherence $C_{l_1}(ρ(t))=\sin^2(ϕ/2)$, and the bipartite entanglement of formation $E_F(t)$ for the reduced pairs $(1,2)$ and $(3,4)$. These quantities are dictated entirely by the single phase $ϕ=(α+1)t$. The fidelity shows oscillatory behavior with amplitude $|\cos(ϕ/2)|$ and reaches a quiescent dynamical regime at $α=-1$, characterized by $F\equiv 1$ for all times. Meanwhile, the coherence follows $C_{l_1}(ρ(t))=\sin^2(ϕ/2)$, with a response sensitivity proportional to $|α+1|$, and fully extinguishes at the stabilization point $α=-1$. The entanglement of formation $E_F(t)$, formulated as an entropic function of $ϕ$, undergoes striped periodic modulations and likewise freezes at the same parameter value. The unification of the phase ties together all observables, showing that larger $|α+1|$ drives faster evolution, with peak susceptibility occurring when $(α+1)t=π/4+kπ/2$. This complete analytical architecture supplies precise reference data suited for small-scale quantum hardware and charts a clear route for incorporating decoherence, thermal effects, and generalizations to larger spin assemblies.

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arXiv2026

Analytic $C_{\ell_1}$ norm of Coherence Evolution for Bell States under a Two-Qubit Superconducting Hamiltonian

We present the first exact analytic study of unitary coherence dynamics in a minimal two qubit superconducting system with zz-coupling and transverse Josephson tunneling. By deriving the full time evolution operator without approximations and propagating all four Bell state initial conditions, we obtain novel closed form time dependent pure state density matrices and an explicit analytic expression for the C_(l_1 ) norm of coherence that, to our knowledge, has not been previously reported in the literature. Two of the Bell states are shown to be invariant under the model dynamics with constant coherence, whereas the other two exhibit controlled, parameter dependent coherence oscillations. The oscillatory behavior is governed by two distinct frequency scales that directly map onto the circuit coupling and tunneling parameters, allowing for predictable tuning of amplitude and periodicity. Numerical visualizations clarify operating regimes for transient enhancement or suppression of coherence. These results deliver compact, analytically tractable tools for parameter optimization and provide a clear foundation for incorporating dissipation and experimental validation.

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arXiv2026

Maximizing Information Flow in Three-Coin Quantum Walk: from Initial Entanglement to Integrated Photonic Implementation

Discrete-time quantum walks are powerful platforms for simulating quantum transport and information processing. Here we introduce a walker on a one-dimensional lattice whose motion is controlled by three entangled coins, each initialized with the Hadamard gate, aiming to maximize information flow. The walker moves only when all three coins yield the same outcome (HHH or TTT), thus coupling the 8-dimensional coin Hilbert space to the position degree of freedom. By analyzing fully separable, fully entangled (GHZ-type) and intermediate initial states, and using the von Neumann entropy of reduced subsystems, we compute the mutual information $I(C;P;t)$ between coin and position. The results show that initial three-partite entanglement accelerates the growth of mutual information by up to 18\% after ten steps (when compared to the lower of the two separable states), although it exhibits short-term non-monotonic dynamics due to quantum interference. For the first time, we introduce a tunable parameter $α$ (amplitude of non-displacement states) and show that the GHZ state reaches a maximum of mutual information at $α\approx 0.71$ - a key finding for optimal control of information flow. Finally, an integrated photonic implementation using polarization, spatial modes and time bins is proposed, where $α$ can be tuned with nonlinear or electro-optic elements. A scalable numerical framework (Python code) for simulations up to $t = 5$ steps is provided. Our findings establish three-partite entanglement as a dynamical resource for maximizing information flow and spatial spreading, with direct applications in quantum state transfer, entanglement-assisted sensing and programmable photonic quantum processors.

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arXiv2026

Entanglement dynamics of a two-qutrits system coupled to a spin chain

In this paper, we investigate the entanglement dynamics of a two qutrits system interacting with a spin environment. Using negativity as the entanglement measure, we study the entanglement dynamics of the system. The calculations show that in cases where the entanglement decays quickly, the environment will have a quantum phase transition.

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arXiv2026

Entanglement-Enhanced Information Dynamics in Triple-Coin Discrete-Time Quantum Walks

This work investigates a discrete-time quantum walk on a one-dimensional lattice driven by three entangled coins, each initialized via a Hadamard operator. The walker moves only when all three coins yield identical outcomes (HHH or TTT), coupling an 8-dimensional coin Hilbert space to the position degree of freedom. We analyze fully separable, fully entangled, and intermediate initial coin states, computing the von Neumann entropy of reduced subsystems to derive the mutual information between coin and position over successive steps. Our results demonstrate that initial tripartite entanglement significantly accelerates the growth of mutual information and enhances coin-position correlations compared to separable initial conditions. Notably, GHZ-type entangled states exhibit non-monotonic short-time dynamics due to interference, yet ultimately yield up to 18% higher mutual information by the tenth step. These findings underscore the role of pre-walk entanglement as a resource for controlling information flow and spatial spreading in quantum-walk-based protocols, with implications for quantum transport, state transfer, and correlation engineering.

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arXiv2025

Analyzing negativity criterion in qubit-qutrit system located in external magnetic fields with the Dzyaloshinskii-Moriya interaction

This investigation delves into the intricate entanglement dynamics exhibited by qubit-qutrit systems when subjected to the intricate dynamics of both the XXX isotropic Heisenberg model and the anisotropic XYZ model. These models are enriched by the presence of Dzyaloshinskii-Moriya (DM) interactions and external magnetic fields, creating a complex interplay of quantum phenomena. The exploration commences by initializing the system in a superposition of spin-coherent states, setting the stage for a nuanced analysis of entanglement evolution over time. By employing the negativity metric as the pivotal criterion for assessing entanglement, we gain insights into the subtle relationships between DM interactions, external magnetic fields, and the entanglement dynamics within this composite system. Through this comprehensive investigation, we aim to unravel the intricate dynamics and behaviors that emerge from the interplay of these fundamental elements, shedding light on the underlying principles governing quantum entanglement in this context.

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arXiv2025

Quantum entanglement dynamics in a three-qubit system interacting with a spin chain

In this article, we investigate the entanglement evolution of three-qubit states in the presence of a spin chain environment. Utilizing negativity as a metric for entanglement assessment, we focus on the GHZ, W, and W_zeta quantum states as the initial system states. We explore and analyze the entanglement dynamics of these states based on various parameters.

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arXiv2025

Quantum entanglement dynamics of the three-qubit W_zeta quantum state coupled to spin chain with ternary interaction

In this study, we explore the dynamics of quantum entanglement using the negativity criterion for the W_zeta quantum state. We investigate changes in negativity in terms of anisotropy parameters, gamma, the strength of the external magnetic field applied to the spin chain, eta, the triple interaction strength, alpha. We examine how these parameters affect the entanglement properties of the system and discuss the implications for quantum information processing and quantum communication protocols. By analyzing the negativity of the W_zeta state under different conditions, we gain insights into the behaviour of entanglement in complex quantum systems. Our results shed light on the intricate interplay between various factors that influence quantum entanglement and provide a foundation for further investigations in this field of research.

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arXiv2025

Investigating the evolution of quantum entanglement of a qubit-qubit system with Dzyaloshinskii-Moriya interaction in the presence of magnetic fields

In this paper, the quantum entanglement dynamics of a qubit qubit compound system in the isotropic XXX Heisenberg and anisotropic XYZ models with DM interaction under magnetic fields is investigated. The system's initial state is considered as a spin coherence state, and the entanglement dynamics of this compound system is analyzed using the negativity criterion as an entanglement measure to assess the impact of DM interaction and magnetic fields.

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