Abstract
Quantum secure direct communication (QSDC) is an important branch of quantum communication that is capable of directly transmitting secret messages over a quantum channel. It may be viewed as a concrete realization of Wyner's wiretap channel theory, which ensures the reliable and secure communication of information in the presence of noise and eavesdropping. Hence it is a fully-fledged quantum-communications protocol, which does not require a separate secret key negotiation phase. By contrast, its quantum key distribution (QKD) counterpart represents a secret key-negotiation protocol, which has to be followed up by a separate classical communication session. The essential difference between these two modes of quantum communication lies in the employment of a block-based data transmission technique, proposed by Long and Liu in 2000. However, the original block-based data transmission requires quantum memory, which is not widely available at the time of writing. Recently, this difficulty has been overcome by using classical coding theory, which has been successfully applied to the single-qubit DL04 QSDC. Here we will present a single-photon-memory QSDC protocol based on entangled pairs of photons. We commence by comparing QSDC to QKD, followed by an example of the single-photon QSDC and single-photon QKD protocol. Then we continue by modifying the so-called two-step QSDC protocol designed for deterministic QKD by reducing the number of qubits in a block into a single one, in which Alice prepares Einstein-Podolsky-Rosen (EPR) photon pairs and partitions them into two parts: the so-called pioneer qubit and the follow-up qubit. The pioneer photon is transferred first to Bob, while the follow-up photon is used either for performing encoding or for eavesdropping detection. Bob extracts the candidate key by combining the two particles of the EPR pair to perform Bell-basis measurement. Then the protocol is transformed into a single-photon-memory QSDC using coding theory. Our theoretical analysis shows that the resultant protocol is robust to individual attacks. Additionally, a high communication efficiency is achieved.
Highlights
The security of information has always been of high significance to humankind
We will demonstrate that the process of quantum communication relying on Quantum secure direct communication (QSDC) is more appealing than quantum key distribution (QKD)-based communication system, since no key distribution, no encryption, and no decryption are necessitated
We review the operational steps of Bennett and Brassard in 1984 (BB84) QKD protocol and DL04 QSDC protocol in Section III and Section IV, respectively
Summary
The security of information has always been of high significance to humankind. An important subfield of secure. The quadrature components of either coherent states, squeezed states, or ‘‘non-classical’’ light beams [24] are modulated by the secret key bits and measured by high-efficiency homodyne (or heterodyne) detectors, which are compatible with off-the-shelf telecommunication technologies [23] The latter offers a low-cost and high-secret-key-rate advantage over DV-QKD for transmission over short distances. In 2000, Long and Liu [36] put forward the first QSDC protocol, which encodes information in the EPR pair quantum states, where - in contrast to QKD solutions - secret information can be transmitted directly through a quantum channel at a high level of security. We will demonstrate that the process of quantum communication relying on QSDC is more appealing than QKD-based communication system, since no key distribution, no encryption, and no decryption are necessitated.
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