Controllable entangled-state transmission in a non-Hermitian trimer Su-Schrieffer-Heeger chain

We propose controllable, robust, and fast entangled-state transmission schemes with the band-gap state of the non-Hermitian trimer Su-Schrieffer-Heeger (SSH3) chain. The non-Hermiticity is induced by the periodic on-site imaginary potential on each unit cell as gain and loss of the SSH3 chain. We realize topologically protected bidirectional entangled-state transmission in an even-sized chain and unidirectional entangled-state transmission in an odd-sized chain and analyze the effect of the imaginary potential on the transmission performance. It is found that the success of the state transmission mainly depends on the on-site imaginary potential of the output port and is independent of the input port. Moreover, the opportune imaginary potential not only can be used to open or close the transmission channel but also can accelerate the transmission without breaking the robustness. Additionally, we discuss the average fidelity with process assessment and experimental feasibility of the present transmission schemes. The controllable, robust, and fast entangled-state transmission schemes enrich the research on quantum information processing with non-Hermitian quantum systems.