Distributed quantum networks require robust protocols for high-capacity, noise-resilient communication between spatially separated nodes. Superdense coding, which leverages shared entanglement to transmit two classical bits per qubit, is a key primitive for benchmarking such networks. However, entanglement degradation from channel noise and decoherence poses major challenges for achieving scalable throughput in practical environments. We introduce a testbed protocol for adaptive superdense coding in distributed quantum networks (DQNs), integrating the five-qubit error correction code with a global, feedback-driven purification routine. By continuously monitoring quantum discord (QD) and entanglement of formation (EoF) via dedicated pilot pairs, our protocol dynamically tunes purification parameters to counteract amplitude and phase damping, while avoiding the loss of entangled pairs inherent to traditional schemes. Simulation results demonstrate that this hybrid quantum-classical approach enhances channel fidelity and throughput under realistic noise, providing a scalable testbed for distributed quantum error correction strategies and hybrid control in next-generation quantum networks.
Distributed quantum networks require robust protocols for high-capacity, noise-resilient communication between spatially separated nodes. Superdense coding, which leverages shared entanglement to transmit two classical bits per qubit, is a key primitive for benchmarking such networks. However, entanglement degradation from channel noise and decoherence poses major challenges for achieving scalable throughput in practical environments. We introduce a testbed protocol for adaptive superdense coding in distributed quantum networks (DQNs), integrating the five-qubit error correction code with a global, feedback-driven purification routine. By continuously monitoring quantum discord (QD) and entanglement of formation (EoF) via dedicated pilot pairs, our protocol dynamically tunes purification parameters to counteract amplitude and phase damping, while avoiding the loss of entangled pairs inherent to traditional schemes. Simulation results demonstrate that this hybrid quantum-classical approach enhances channel fidelity and throughput under realistic noise, providing a scalable testbed for distributed quantum error correction strategies and hybrid control in next-generation quantum networks.
Superdense Coding is a cornerstone in secure quantum communication, exploiting pre-shared entanglement to encode two classical bits within a single qubit. However, noise and decoherence deteriorate entanglement quality, restricting both fidelity and channel capacity in practical settings. Traditional methods, such as error correcting codes or entanglement distillation, are generally inadequate for dynamically varying noise conditions. Moreover, reliance on fidelity alone may fail to capture more subtle noise effects. This work introduces an adaptive protocol that integrates the five-qubit perfect code with a novel global adaptive purification that avoids discarding entangled pairs. By monitoring two information entropy-based metrics, quantum discord (QD) and entanglement of formation (EoF) from pilot pairs, we dynamically tune a global unitary to counteract noise. Our simulations, under both amplitude and phase damping, indicate that this integrated strategy could significantly enhance superdense coding robustness while preserving high throughput, thereby offering a scalable pathway toward a high-capacity quantum internet.
Quantum communication protocols such as superdense coding enable high-capacity information transfer using quantum entanglement. However, their performance is significantly affected by environmental noise and decoherence. This study presents an enhanced simulation framework for evaluating the Steane 7-qubit error correction code applied to superdense coding under realistic noise conditions. Building upon earlier models, the proposed work introduces robust circuit depth control mechanism and noise-aware simulation using Qiskit Aer to analyze depolarizing, amplitude damping, and phase damping errors. The system automatically encodes, decodes, and measures fidelity across varying noise probabilities, classifying results into performance tiers based on resilience. Comprehensive visualization through trend plots, heatmaps, and tier distributions offers clear insights into the impact of noise on quantum communication fidelity. The findings demonstrate that Steane encoding stabilizes fidelity within moderate noise levels, thereby improving the robustness of dense coding. This enhanced model provides a reproducible and scalable approach for studying quantum error correction, contributing to the design of noise-tolerant quantum communication networks.
Abstract We introduce an escort-qubit–assisted protocol that restores and stabilizes superdense coding capacity in the presence of amplitude damping channel (ADC) noise. The protocol is analyzed under three fundamental noisy configurations: amplitude damping acting on Alice’s subsystem, on Bob’s subsystem, and on both subsystems covering all practically relevant scenarios. In the absence of protection, we show that ADC effects cause a monotonic degradation of the superdense coding capacity, driving it below the classical limit in the strong decoherence regime and completely erasing the quantum advantage. Our escort-qubit protocol overcomes this limitation by coherently tracking the channel-induced Kraus trajectories during entanglement distribution. Post-selection of the no-flip trajectory, projects the shared state onto a maximally entangled resource state, thereby recovering the optimal superdense coding capacity of two classical bits, independent of the noise strength and noisy configuration. Importantly, when all ADC trajectories are taken into account, the resulting average capacity although inherently suboptimal remains strictly above both the classical limit and the unprotected capacity across the entire decoherence range. These results establish the escort-qubit protocol as a powerful, scalable, and experimentally viable approach for preserving quantum advantage and enhancing information throughput in noisy quantum communication networks.
We introduce a robust quantum communication protocol that integrates classical error-control coding, entanglement distribution, and superdense coding. Classical error-correcting codes are used to mitigate dark counts and photon losses by determining the positions of qubit transmissions and protecting the data embedded through superdense coding. We derive conditions on the employed codes that guarantee successful error correction under a bounded error-frequency model. Moreover, upper bounds are derived on the performance of conventional superdense coding protected by classical error correction. It is shown that, under the same constraints on error frequency, suitable code configurations of the proposed protocol can exceed those upper bounds both in terms of data rate and energy efficiency. Finally, we develop a physical error model based on fiber attenuation, detector efficiency, dark counts, and time-slot duration, and use it to evaluate the effective performance of different configurations of error-correcting codes. The proposed approach is primarily suited for short-distance quantum links, as in Quantum Local Area Network (QLAN) where it can provide high communication throughput while integrating entanglement distribution directly into the communication process.
Quantum communication protocols, such as superdense coding, offer significant advantages in information transfer by leveraging quantum entanglement. However, practical implementations are hindered by the presence of noise and decoherence in quantum systems. This study investigates the effectiveness of the Steane 7-qubit error correction code in mitigating the impact of noise on the superdense coding protocol. Simulations were performed using Qiskit Aer, incorporating depolarizing, amplitude damping, and phase damping noise models at varying strengths. The error rates were evaluated across multiple trials to assess the robustness of the encoded communication. The results demonstrate that the Steane code substantially improves the fidelity of information transmission, with varying levels of protection depending on the type of noise present. These findings contribute to a better understanding of error correction strategies for reliable quantum communication in noisy environments.
Abstract The superdense coding protocol is essential for quantum communication, allowing more efficient data transmission. This protocol facilitates the transfer of two bits of classical information using just one qubit by leveraging a pre-existing pair of Bell states. To achieve this capability, traditional implementations of superdense coding depend on entangled states, such as Bell states. This paper introduces a novel circuit that utilizes Bell diagonal states to implement the superdense coding protocol. We provide detailed instructions for the procedure using IBM’s Quantum Computing Lab, enabling practical applications in real-world contexts. Furthermore, the paper highlights the security features of this protocol, emphasizing its significance for secure communication in quantum networks. The combination of efficiency and security represents a notable advancement in quantum information science. We implemented and tested the proposed superdense coding circuit on the IBM Q quantum computing platform using Qiskit. Through extensive simulations on IBM’s Statevector and QASM simulators, we assessed the performance of the circuit based on Bell diagonal states (BDS)in terms of accuracy, noise resilience, and resource efficiency. Our findings indicate that, while Bell diagonal states pose challenges related to noise and decoherence, they also provide potential advantages in reducing qubit usage and enhancing error correction. This research contributes to the exploration of alternative techniques for superdense coding, which may have applications in quantum communication and future quantum networks. However, additional theoretical and experimental investigations are necessary to fully evaluate the scalability and practicality of this approach.