Single-photon transport in nonideal chiral photon-atom interaction structures generally contains information backflow and thus limits the capabilities to transfer information between distant emitters in cascaded quantum networks. Here, in the nonideal chiral case, a $V$-type atom coupled to a waveguide is proposed to realize completely unidirectional transmission of the single photons in a superposition state of different frequencies. A microwave field is introduced to drive the two excited states of the atom and results in photon conversion between two transitions. By adjusting the Rabi frequency and the phase of the external driving field, the transport behaviors of incident photons with specific frequencies can be optimized to complete transmission or reflection. Based on the constructive interferences between photons from different traveling paths, the transmission probabilities of the specific-frequency photons could be enhanced. Due to photon conversions with compensating the dissipations and ensuring the complete destructive interference, the ideal unidirectional transmission contrast can be maintained to $\pm 1$, even when the atom has dissipations into the nonwaveguide modes.

中文翻译：

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非理想手性光子-原子相互作用下单光子的单向传输

非理想手性光子-原子相互作用结构中的单光子传输通常包含信息回流，因此限制了级联量子网络中远距离发射器之间传递信息的能力。在非理想的手性情况下，$V$提出了一种耦合到波导的原子型原子，以实现在不同频率的叠加状态下单光子的完全单向传输。引入微波场来驱动原子的两个激发态，并导致两个跃迁之间的光子转换。通过调整拉比频率和外部驱动场的相位，可以优化具有特定频率的入射光子的传输行为，以完成传输或反射。基于来自不同行进路径的光子之间的相长干涉，可以提高特定频率光子的传输概率。由于光子转换具有补偿耗散并确保完全破坏性干扰的作用，因此可以保持理想的单向传输对比度，以达到$\pm \mathrm{1个}$，即使原子已耗散到非波导模式。