Quantum secure direct communication (QSDC) can transmit secret messages without keys, making it an important branch of quantum communication. We present a hybrid entanglement-based quantum secure direct communication (HE-QSDC) protocol with simple linear optical elements, combining the benefits of both continuous variables (CV) and discrete variables (DV) encoding. We analyze the security and find that the QSDC protocol has a positive security capacity when the bit error rate is less than 0.073. Compared with previous DV QSDC protocols, our protocol has higher communication efficiency due to performing nearly deterministic Bell-state measurement. On the other hand, compared with CV QSDC protocol, this protocol has higher fidelity with large α. Based on these advantages, our protocol may provide an alternative approach to realize secure communication.

量子安全直接通信（QSDC）无需密钥即可传输秘密消息，使其成为量子通信的重要分支。我们提出了一种基于混合纠缠的量子安全直接通信（HE-QSDC）协议，具有简单的线性光学元件，结合了连续变量（CV）和离散变量（DV）编码的优点。我们对安全性进行了分析，发现当误码率小于0.073时，QSDC协议具有正的安全能力。与之前的DV QSDC协议相比，我们的协议由于执行近乎确定性的贝尔状态测量而具有更高的通信效率。另一方面，与CV QSDC协议相比，该协议具有更高的保真度和较大的α。基于这些优点，我们的协议可以提供一种替代方法来实现安全通信。