This paper investigates the behavior of two fundamental types of multipartite entangled states, namely GHZ(3) and W(3) states under Gaussian-distributed amplitude perturbations and White noise model. The Uhlmann–Jozsa fidelity is taken to be the quantitative measure to show the overall degradation of the quantum states and is implemented via TQIX: a tool specifically designed for quantum state measurement and related applications. While fidelity analysis captures the progressive decay of quantum states under noise, it offers only limited understanding regarding the state decay and does not provide a detailed analysis of how entanglement structures respond to noise models. To reveal the phase-space characteristics and nonclassical signatures of three-qubit entangled states, we employ the spin Wigner function using equal-angle projection. This approach reveals a continuous fading of quantum coherence with increasing noise strength, ultimately providing a clear picture of transition toward classical-like behavior in phase space. This combined qualitative–quantitative framework provides deeper understanding of how different entanglement structures respond to noise, offering practical applications for designing and implementing noise resilient protocols in quantum computing and quantum information processing.
This paper investigates the behavior of two fundamental types of multipartite entangled states, namely GHZ(3) and W(3) states under Gaussian-distributed amplitude perturbations and White noise model. The Uhlmann–Jozsa fidelity is taken to be the quantitative measure to show the overall degradation of the quantum states and is implemented via TQIX: a tool specifically designed for quantum state measurement and related applications. While fidelity analysis captures the progressive decay of quantum states under noise, it offers only limited understanding regarding the state decay and does not provide a detailed analysis of how entanglement structures respond to noise models. To reveal the phase-space characteristics and nonclassical signatures of three-qubit entangled states, we employ the spin Wigner function using equal-angle projection. This approach reveals a continuous fading of quantum coherence with increasing noise strength, ultimately providing a clear picture of transition toward classical-like behavior in phase space. This combined qualitative–quantitative framework provides deeper understanding of how different entanglement structures respond to noise, offering practical applications for designing and implementing noise resilient protocols in quantum computing and quantum information processing.
This paper investigates the behavior of two fundamental types of multipartite entangled states, namely GHZ(3) and W(3) states under Gaussian-distributed amplitude perturbations and White noise model. The Uhlmann-Jozsa fidelity is taken to be the quantitative measure to show the overall degradation of the quantum states, and is implemented via TQIX : a tool specifically designed for quantum state measurement and related applications. While fidelity analysis captures the progressive decay of quantum states under noise, it offers only limited understanding regarding the state decay and doesn't provide a detailed analysis of how entanglement structures respond to noise models. To reveal the phase-space characteristics and nonclassical signatures of three-qubit entangled states, we employ the spin Wigner function using equal-angle projection. This approach reveals a continuous fading of quantum coherence with increasing noise strength, ultimately providing a clear picture of transition toward classical-like behavior in phase space. This combined qualitative-quantitative framework provides deeper understanding of how different entanglement structures respond to noise, offering practical applications for designing and implementing noise resilient protocols in quantum computing, and quantum information processing.
Abstract Reliable verification of multipartite entanglement is a prerequisite for quantum information processing. However, the interplay between statistical fluctuations and systematic errors in Quantum State Tomography (QST) often obscures genuine quantum correlations. In this work, we perform a numerical benchmarking of QST performance for three-qubit GHZ and W states under a comprehensive noise model that incorporates Poissonian counting statistics, random unitary perturbations, white noise, and source instability. Beyond standard fidelity analysis, we utilize entanglement negativity and residual entanglement to investigate how these states respond to different noise sources. Our results highlight the response characteristics of entanglement measures and fidelity to experimental imperfections. We provide a quantitative analysis of the robustness profiles for both states, noting the entanglement decay and the evolution of residual entanglement under local unitary noise. Furthermore, we establish that employing an overcomplete tomographic set provides a slight advantage in mitigating systematic errors compared to standard informationally complete schemes. These findings provide a useful reference for analyzing the potential impacts of measurement artifacts and genuine decoherence in experimental setups.
In distributed quantum computing, quantum networks provide a potential infrastructure for long-range quantum information processing. Controlled quantum teleportation (CQT) is a key practically relevant protocol that can connect two parties on a network and enables a third party, the controller to allow or abort the secure teleportation of an arbitrary single-qubit state between the two parties. We investigate the robustness of a three-qubit GHZ resource under bit-flip, phase-flip, depolarizing, and amplitude-damping noise. Using the Kraus-operator formalism, we characterize the noisy resource through multipartite quantum discord, genuine multipartite concurrence (GMC), localizable entanglement (LE), and CQT fidelity. We also outline a proof-of-concept photonic implementation for preparing the three-qubit GHZ resource and realizing the CQT protocol, which could enable experimental investigation of the effects of noise. Our results show that bit-flip and amplitude-damping noise generally preserve useful mutipartite quantum correlations over broader noise parameter ranges. Interestingly, multipartite discord exhibits freezing under bit-flip noise over a finite parameter regime. Moreover, discord can persist beyond the sudden death of genuine multipartite entanglement, revealing the distinct robustness of nonclassical correlations. We further demonstrate that CQT fidelity which characterizes the performance of CQT can exceed the classical threshold even after GMC vanishes, while LE more closely reflects the operational usefulness of the noisy resource. These findings highlight the complementary roles of quantum correlations and entanglement in assessing the resilience of GHZ-based protocols.
Abstract Gaussian states, characterized by probability distributions in phase-space representations, play a fundamental role in quantum information processing. Despite their mathematical tractability, the presence of noise imposes limitations on achieving quantum protocols, impacting their effectiveness in continuous-variable quantum systems for various communication and computation tasks. Hence, investigating quantum entanglement and quantum correlations within the coherence of Gaussian states in noisy channels holds significant importance. In this study, we introduce and investigate a framework designed to precisely define and explore the dynamic evolution of quantum correlations within twomode Gaussian states subjected to the effects of a Gaussian thermal environment. We elucidate the temporal progression of quantum correlations within an open system comprising two interconnected bosonic modes embedded in a Gaussian thermal environment. We explore the impact of the environment by considering the evolution of the initial parameters of the input states. We measure the quantum correlations by employing the quantifiers: the Gaussian logarithmic negativity (GLN) N and the Gaussian quantum discord (GQD) D G . The behavior of these quantum correlation quantifiers is intricately related to the parameters of the input states utilized in the analysis. We demonstrate that the GQD D G serves as an appropriate measurement quantifier in capturing fundamental quantum correlations, outperforming other quantifiers. Furthermore, our findings reveal that the GQD D G exhibits greater resilience compared to GLN N , showing a reduced sensitivity to external influences.
Noise is a major challenge in quantum computing, affecting the reliability of quantum protocols. In this work, we analytically study the impact of various noise processes, such as depolarization, bit flip, and phase flip, on the quantum state teleportation protocol. Each noise process is modeled as a quantum channel and is applied individually to all qubits after the corresponding unitary operations to simulate realistic conditions. We evaluate the fidelity between the ideal and noisy teleported states to quantify the effect of noise. Our analysis shows that the fidelity decreases polynomially, in general, as the noise strength increases for all noise types, highlighting the sensitivity of state teleportation to different noise mechanisms. However, in the low noise regime, the fidelity decreases only linearly, indicating the robustness of the teleportation protocol. These results provide insight into error characterization and can inform strategies for noise mitigation in practical quantum computing applications.
This work investigates the transformation and behavior of quantum states using Bloch sphere visualizations to provide an intuitive understanding of quantum phenomena, incorporating concepts from both quantum computing and nano physics.By applying quantum gates such as Hadamard, Pau-li-X, Pauli-Y, and Pauli-Z, the evolution of qubits is demonstrated.The study leverages principles of quantum superposition, entanglement, and coherence, which are pivotal in nanoscale systems, to analyze qubit dynamics.Additionally, phase noise, a critical factor in nanoscale quantum devices, is introduced to simulate real-world quantum errors, and fidelity is calculated to measure the robustness of quantum states under such noise.The approach addresses noise resilience in nanoscale quantum devices by combining phase noise analysis, fidelity measurement, and quantum entanglement.The novelty of the approach is emphasized through comparisons with the existing studies on quantum state tomography and machine learning-based quantum optimization.Results will have direct applications in quantum key distribution (QKD), quantum error correction, and secure quantum communication.