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Entropy

High-Dimensional and Multi-Intensity One-Photon-Interference Quantum Secure Direct Communication

Yu-Ting Lei, Xiangjie Li, Xing-Bo Pan, Yun-Rong Zhang, Gui‐Lu Long

Published Mar 22, 2025• 2 citations
Publisher

Abstract

As a novel paradigm in quantum communication, quantum secure direct communication (QSDC) enables secure, reliable, and deterministic information transmission, leveraging the principles of quantum mechanics. One-photon-interference QSDC is particularly attractive because it mitigates the vulnerabilities in measurement devices while extending transmission distances. In this paper, we propose a high-dimensional one-photon-interference QSDC protocol that exploits the advantages of high-dimensional encoding in the phase of weak coherent pluses to further enhance transmission distances and improve secrecy channel capacity. The security of this protocol is analyzed using quantum wiretap channel theory, and its resistance to common quantum threats is discussed. Numerical simulations demonstrate that our protocol outperforms its predecessor in terms of its secrecy capacity and extends the maximum communication distance achievable up to 494 km, which is over 13% longer than the two-dimensional case, effectively doubling the transmission length of traditional protocols. These improvements highlight the protocol's potential for use in quantum communication applications in this era of frequent data breaches and information leaks.

DOI
10.3390/e27040332

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As a novel paradigm in quantum communication, quantum secure direct communication (QSDC) enables secure, reliable, and deterministic information transmission, leveraging the principles of quantum mechanics. One-photon-interference QSDC is particularly attractive because it mitigates the vulnerabilities in measurement devices while extending transmission distances. In this paper, we propose a high-dimensional one-photon-interference QSDC protocol that exploits the advantages of high-dimensional encoding in the phase of weak coherent pluses to further enhance transmission distances and improve secrecy channel capacity. The security of this protocol is analyzed using quantum wiretap channel theory, and its resistance to common quantum threats is discussed. Numerical simulations demonstrate that our protocol outperforms its predecessor in terms of its secrecy capacity and extends the maximum communication distance achievable up to 494 km, which is over 13% longer than the two-dimensional case, effectively doubling the transmission length of traditional protocols. These improvements highlight the protocol's potential for use in quantum communication applications in this era of frequent data breaches and information leaks.
Quantum secure direct communication (QSDC) is a quantum communication paradigm that transmits confidential messages directly using quantum states. Measurement-device-independent (MDI) QSDC protocols can eliminate the security loopholes associated with measurement devices. To enhance the practicality and performance of MDI-QSDC protocols, we propose a one-photon-interference MDI QSDC (OPI-QSDC) protocol which transcends the need for quantum memory, ideal single-photon sources, or entangled light sources. The security of our OPI-QSDC protocol has also been analyzed using quantum wiretap channel theory. Furthermore, our protocol could double the distance of usual prepare-and-measure protocols, since quantum states sending from adjacent nodes are connected with single-photon interference, which demonstrates its potential to extend the communication distance for point-to-point QSDC.
Quantum secure direct communication (QSDC) directly transmits confidential information over a quantum channel. In this context, it is important to take into account the multi-photon effect when using weak coherent laser pulses as the quantum source. Here we propose a multi-intensity QSDC (MI-QSDC) protocol where laser pulses having different intensities are used for secure communication in a fashion reminiscent of decoy states, where only signal intensity pulses are used for key exchange. Pulses of all intensities are used both for information transmission and eavesdropping detection in the MI-QSDC. The statistical fluctuations associated with practical finite block-length in QSDC are also considered and a tight secrecy capacity bound is given. The simulation results show that the proposed protocol is capable of communicating over a distance on the order of 100 km by relying on a finite block-length of sending 1014pulses.
Abstract Quantum secure direct communication (QSDC) guarantees both the security and reliability of information transmission using quantum states. One-photon-interference QSDC (OPI-QSDC) is a technique that enhances the transmission distance and ensures secure point-to-point information transmission, but it requires complex phase locking technology. This paper proposes a mixed-encoding one-photon-interference QSDC (MO-QSDC) protocol that removes the need for phase locking technology. Numerical simulations demonstrate that the MO-QSDC protocol could also beat the PLOB bound.
Quantum secure direct communication (QSDC) guarantees both the security and reliability of information transmission using quantum states. One-photon-interference QSDC (OPI-QSDC) is a technique that enhances the transmission distance and ensures secure point-to-point information transmission, but it requires complex phase locking technology. This paper proposes a mixed-encoding one-photon-interference QSDC (MO-QSDC) protocol that removes the need for phase locking technology. Numerical simulations demonstrate that the MO-QSDC protocol could also beat the PLOB bound.
Current quantum secure direct communication (QSDC) protocols guarantee communication security by estimating the error rates of photons in the X and Z bases. This take the reference frame calibration between communicating parties as a necessary prerequisite. However, in mobile communications scenarios, achieving continuous and accurate reference frame calibration poses significant challenges. To address this issue, this paper proposes a reference-frame-independent (RFI) QSDC protocol. This protocol only requires ensuring the calibration accuracy of one direction of the reference frame, while allowing a misalignment angle βββ in the other two directions. To improve the protocol's robustness against reference frame fluctuations, we introduce a βββ-independent parameter C into the security analysis framework and rederive the protocol's security bounds. Additionally, we construct a system model and optimize the pulse intensity of the signal states, enabling the protocol to achieve optimal performance under each level of channel attenuation. At an attenuation of 10 dB (corresponding to a communication distance of 25 km), the secrecy message capacities for $β= 0^{ \circ} $ and $45^{ \circ} $ are 8.765×10−68.765 \times10^{-6}8.765×10−6 bit/pulse and 4.150×10−64.150 \times10^{-6}4.150×10−6 bit/pulse, respectively. Compared with the single-photon-based QSDC, the communication distance of the protocol proposed in this paper is significantly extended. When $β= 0^{ \circ} $ and $45^{ \circ} $, the maximum transmission distances of the RFI QSDC protocol are 27.875 km and 26.750 km, which is about 155.9 % and 149.7 % of that of the single-photon-based QSDC protocol.
Considering the high cost and high quantum resource consumption associated with measurement-device-independent quantum secure direct communication (MDI-QSDC), this paper designs an MDI-QSDC protocol based on a semi-quantum environment. This protocol appropriately reduces communication cost and quantum resource consumption by imposing certain restrictions on the quantum capabilities of one of the communication parties. Meanwhile, the protocol also ensures the high security of communication and increases secrecy channel capacity. Furthermore, given that 1-qubit in 2-dimensional system can encode a maximum of only 1-classical bit of information, the paper extends the proposed protocol toddd-dimensional system. This extension further improves communication efficiency and secrecy channel capacity, laying the foundation for future research on the diversity and efficiency of information transmission.