Twin-field quantum key distribution (TF-QKD) can overcome the fundamental rate-loss limit without quantum repeaters, which has stimulated intense research interests both in theory and experiment. Recently, TF-QKD protocols with discrete-phase-randomized sources have been widely studied. However, all these protocols require the phase postselection step in the test mode. To bypass this step, we propose a discrete-phase-randomized TF-QKD protocol without phase postselection in the test mode, which reduces the amount of information transmitted in the classical post-processing stage and thus reduces the consumption of secret keys in the authentication of classical information. Moreover, the numerical simulation of our protocol can be easily solved by linear programming. Simulation results show that, with only a few number of discrete phases, our protocol can beat the rate-loss bound and approximate the case of continuous phases, which is very practical in some real-life implementations of TF-QKD.

双场量子密钥分配（TF-QKD）可以在没有量子中继器的情况下克服基本的速率损失限制，这在理论和实验上都激发了强烈的研究兴趣。最近，具有离散相位随机源的 TF-QKD 协议得到了广泛的研究。但是，所有这些协议都需要在测试模式下进行相位后选择步骤。为了绕过这一步，我们提出了一种在测试模式下没有相位后选择的离散相位随机化 TF-QKD 协议，它减少了经典后处理阶段传输的信息量，从而减少了认证中密钥的消耗的经典信息。此外，我们协议的数值模拟可以通过线性规划轻松解决。仿真结果表明，只有少数离散相，