Deterministic secure quantum communication under vacuum fluctuation
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THE EUROPEAN PHYSICAL JOURNAL D
Regular Article
Deterministic secure quantum communication under vacuum fluctuation Zhiming Huang1 and Zhimin He2,3,a 1 2 3
School of Economics and Management, Wuyi University, Jiangmen 529020, P.R. China School of Electronic and Information Engineering, Foshan University, Foshan 528000, P.R. China Center for Quantum Computing, Peng Cheng Laboratory, Shenzhen 518055, P.R. China Received 22 June 2020 / Received in final form 23 July 2020 Published online 1 September 2020 c EDP Sciences / Societ`
a Italiana di Fisica / Springer-Verlag GmbH Germany, part of Springer Nature, 2020 Abstract. A real quantum system is unavoidably affected by external environment, which would produce noise or decoherence, and reduce the efficiency of quantum communication in realistic circumstance. In this paper, we present a noisy deterministic secure quantum communication (DSQC) scheme. We find that fidelity has close relation with quantum coherence and declines to a stable value with decoherent time. Small two-atom distance can improve the fidelity and coherence, and a reflecting boundary can effectively inhibit fidelity and coherence from degradation under the effect of vacuum fluctuation. Our study would be helpful to promote the communication efficiency of open quantum system.
1 Introduction The fundamental principles of quantum mechanics are applied to information communication, which leads to the emergence of many secure and important quantum communication protocols. For instance, quantum key distribution [1–3] lets two remote legitimate users share a secret key with unconditional security. Unlike quantum key distribution, quantum direct secure communication [4] can transfer secret messages directly and safely without a private key to encrypt them. Another class of instantaneous quantum communication DSQC requires transmitting some classical information for reading the secret message [5], different from quantum direct secure communication in which the secret message can be obtained without transferring any classical message. In real quantum communication, quantum system inevitably interacts with the surroundings, which may result in the reduction of quantum resource, causing socalled noise or decoherence. For example, vacuum fluctuation of quantum field as the origin of noise would exert important impact on quantum communication. Thus, how vacuum fluctuation affects the quantum communication is an interesting and valuable research issue. Recently, we examine the influences of fluctuating quantum field on quantum communication schemes [6–8]. On the other hand, the presence of boundary can profoundly affect the fluctuation of vacuum field, and can generate novel field effect, such as the Casimir effect [9]. In this article, we would investigate DSQC affected by fluctuating quantum a
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field and the protection of DSQC with a perfectly reflecting boundary, and the relation between the noisy DSQC performance and quantum coherence.
2 Performance of noisy DSQC scheme Recently,
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