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Laser Physics

Improving the capacity of quantum dense coding with both spontaneous emission and dephasing by non-Hermitian operation

Fei Chen, Yang Leng

Published Apr 17, 2024• 3 citations
Publisher

Abstract

Abstract Using a non-Hermitian operation approach, we propose a scheme to improve quantum dense coding of a qubit-qubit system interacting with a zero-temperature reservoir with both spontaneous emission and dephasing. By solving the master equation of the two-qubit system, we numerically obtain the final capacity of quantum dense coding. The numerical results show explicitly that the non-Hermitian operation indeed helps to improve the non-Hermitian operation from amplitude-phase decoherence. In particular, non-Hermitian operations can protect quantum dense coding more efficiently in the case of strong decay rates than those with small decay rates.

DOI
10.1088/1555-6611/ad3aec

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Abstract Using a non-Hermitian operation approach, we propose a scheme to improve quantum dense coding of a qubit-qubit system interacting with a zero-temperature reservoir with both spontaneous emission and dephasing. By solving the master equation of the two-qubit system, we numerically obtain the final capacity of quantum dense coding. The numerical results show explicitly that the non-Hermitian operation indeed helps to improve the non-Hermitian operation from amplitude-phase decoherence. In particular, non-Hermitian operations can protect quantum dense coding more efficiently in the case of strong decay rates than those with small decay rates.
Abstract We propose a novel method to enhance the capacity of quantum dense coding under amplitude damping noise using non-Hermitian operations. With the assistance of non-Hermitian operations, we show that the capacity of quantum dense coding can always be larger than 1 for any two-qubit states. In particular, the non-Hermitian operation can improve quantum dense coding more efficiently in the case of strong decoherence strength than those with small decoherence strength. Our results shed new light on the protection of quantum dense coding in a quantum environment.
Abstract Decoherence suppression from disturbance of the environment is an essential task in quantum information processing. Using the non-Hermitian operation approach, decoherence suppression of a qubit system interacting with a zero-temperature reservoir with both spontaneous emission and dephasing is investigated. We derive the exact analytical expressions of the quantum fidelity and find that quantum coherence can be significantly enhanced by controlling the non-Hermitian operator parameters. In particular, the non-Hermitian is more effective in the case of strong decay rates and show better inhibition effect on dephasing process than the spontaneous emission process.
Abstract We study the dynamic behavior of quantum super dense coding between two uncoupled qubits, which are immersed in a common Ohmic environment. We examine the validity of local non-Hermitian operations in the amplification of quantum super dense coding. In particular, using analytical and numerical investigations, we show explicitly that the capacity of quantum super dense coding can be greatly amplified with the assistance of a local non-Hermitian operation, i.e. a parity-time symmetric operation. This sheds new light on the protection of quantum super density.
Abstract Using the non-Hermitian operation approach, we propose a scheme to protect and enhance quantum dense coding from correlated amplitude damping (AD) decoherence. In contrast to the results of memoryless AD channel, we show that the memory effects play a significant role in the suppression of quantum dense coding sudden death. Moreover, we find that the damaged quantum dense coding can be effectively enhanced by using the non-Hermitian operation. Furthermore, the freezing phenomenon of quantum dense coding can be detected by using the optimal non-Hermitian operation.
Abstract This paper explores enhancing quantum dense coding capacity in finite-temperature decoherence environments via parity-time ( PT ) symmetric operations. We derive the master equation for a two-qubit system in a thermal bath, analyzing dense coding dynamics with and without PT symmetry operations. Without PT operations, the quantum dense coding capacity is highly sensitive to temperature parameter and decoherence rate, losing its advantage at high temperatures. Introducing a local PT symmetric operation on one qubit restores and surpasses the noiseless capacity. Additionally, numerical analysis demonstrates that by adjusting the non-Hermiticity, the optimal protection rate can always exceed 1. Our findings demonstrate PT symmetric operations as a novel tool to protect quantum correlations and enhance information transmission in realistic thermal settings, offering insights for robust quantum communication protocols.
Abstract Using the non-Hermitian operation approach, the enhanceable capacity of quantum dense coding can be realized in the quantum spin chain channel. We derive the exact analytical expressions of the quantum dense coding and in detail investigate the influence of non-Hermitian operator parameters on the quantum dense coding. We find that the non-Hermitian operator process can obviously enhance the quantum dense coding. In particular, we show that the optimal capacity of quantum dense coding can always be larger than 1 with the assistance of non-Hermitian operations.