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.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.

Feb 26, 20260 citations

Coherence evolution in two-qubit system going through amplitude damping channel

Ming‐Jing Zhao, Teng Ma, Yu-Quan Ma

arXiv:1712.09769Science China Physics Mechanics and AstronomyOct 30, 201725 citations

Enhanced Superdense Coding over Correlated Amplitude Damping Channel

Yan‐Ling Li, Dong-Mei Wei, Chuanjin Zu +1 more

Quantum channels with correlated effects are realistic scenarios for the study of noisy quantum communication when the channels are consecutively used. In this paper, superdense coding is reexamined under a correlated amplitude damping (CAD) channel. Two techniques named as weak measurement and environment-assisted measurement are utilized to enhance the capacity of superdense coding. The results show that both of them enable us to battle against the CAD decoherence and improve the capacity with a certain probability. Remarkably, the scheme of environment-assisted measurement always outperforms the scheme of weak measurement in both improving the capacity and successful probability. These notable superiorities could be attributed to the fact that environment-assisted measurement can extract additional information from the environment and thus it performs much better.Quantum channels with correlated effects are realistic scenarios for the study of noisy quantum communication when the channels are consecutively used. In this paper, superdense coding is reexamined under a correlated amplitude damping (CAD) channel. Two techniques named as weak measurement and environment-assisted measurement are utilized to enhance the capacity of superdense coding. The results show that both of them enable us to battle against the CAD decoherence and improve the capacity with a certain probability. Remarkably, the scheme of environment-assisted measurement always outperforms the scheme of weak measurement in both improving the capacity and successful probability. These notable superiorities could be attributed to the fact that environment-assisted measurement can extract additional information from the environment and thus it performs much better.

EntropyJun 16, 20198 citations

Superdense coding in noisy environments: A quantum trajectory approach

Jin Woo Jun

Using the theory of quantum trajectories, we study the classical capacity $\mathbf{C}$ of noisy quantum channels in the superdense coding protocol. We apply the two models that generalize single-qubit noisy channels, such as amplitude damping and phase flip, to the many-qubit situation. Our numerical results show that the quantum trajectory approach is suitable for modeling the superdense coding protocol in realistic environments.Using the theory of quantum trajectories, we study the classical capacity $\mathbf{C}$ of noisy quantum channels in the superdense coding protocol. We apply the two models that generalize single-qubit noisy channels, such as amplitude damping and phase flip, to the many-qubit situation. Our numerical results show that the quantum trajectory approach is suitable for modeling the superdense coding protocol in realistic environments.

Physical Review AJun 2, 20066 citations

Single qubit operations with base squeezed coherent states

Sergey A. Podoshvedov

Optics CommunicationsOct 18, 201218 citations

Using the theory of quantum trajectories, we study the classical capacity

\mathbf{C}

of noisy quantum channels in the superdense coding protocol. We apply the two models that generalize single-qubit noisy channels, such as amplitude damping and phase flip, to the many-qubit situation. Our numerical results show that the quantum trajectory approach is suitable for modeling the superdense coding protocol in realistic environments.