We present a theoretical investigation of Majorana zero mode (MZM) assisted spin pumping which consists of a quantum dot (QD) and two normal leads. When the coupling between the MZM and the QD is absent, d.c. pure spin current can be excited by a rotating magnetic field where low energy spin down electrons are flipped to high energy spin up electrons by absorbing photons. However, when the coupling is turned on, the d.c. pure spin current vanishes, and an a.c. charge current emerges with its magnitude independent of the coupling strength. We reveal that this change is due to the formation of a highly localized MZM assisted topological Andreev state at the Fermi level, which allows only the injection of electron pairs with opposite spin into the QD. By absorbing or emitting photons, the electron pairs are separated to opposite spin electrons, and then return back to the lead again, generating an a.c. charge current without spin polarization. We demonstrate the switching from d.c. pure spin current to a.c. charge current based on both Kitaev model and a more realistic topological superconductor nanowire. Although this switching can also be induced by partially separated Andreev bound state (ps-ABS) in the topological trivial phase, it is extremely unstable and highly sensitive to the Zeeman field, which is different from the switching induced by MZM. Our result suggests that quantum spin pumping may be a feasible local transport method for detecting the presence of MZMs at the ends of a superconducting nanowire.

我们提出了马约拉纳零模式（MZM）辅助自旋泵浦的理论研究，该泵浦由量子点（QD）和两个普通引线组成。当 MZM 和 QD 之间不存在耦合时，旋转磁场可以激发直流纯自旋电流，其中低能自旋电子通过吸收光子翻转为高能自旋电子。然而，当耦合打开时，直流纯自旋电流消失，并且出现交流充电电流，其大小与耦合强度无关。我们发现这种变化是由于在费米能级形成了高度局域化的 MZM 辅助拓扑安德烈夫态，它只允许具有相反自旋的电子对注入到量子点中。通过吸收或发射光子，电子对被分离成相反的自旋电子，然后再次返回到引线，产生没有自旋极化的交流充电电流。我们基于 Kitaev 模型和更现实的拓扑超导体纳米线演示了从直流纯自旋电流到交流充电电流的切换。尽管这种开关也可以由拓扑平凡相中的部分分离的安德烈夫束缚态（ps-ABS）引起，但它极不稳定，并且对塞曼场高度敏感，这与MZM引起的开关不同。我们的结果表明，量子自旋泵浦可能是一种可行的局部传输方法，用于检测超导纳米线末端 MZM 的存在。