We study charge transport of a topological superconductor connected todifferent electromagnetic environments using a low-energy description whereonly the Majorana bound states in the superconductor are included. Extendingearlier findings who found a crossover between perfect Andreev reflection withconductance $2e^2/h$ to a regime with blocked transport when the resistance ofthe environment is larger than $2e^2/h$, we consider Majorana bound statescoupled to metallic dots. in particular, we study two topologicalsuperconducting leads connected by a metallic quantum dot in both the weaktunneling and strong tunneling regimes. For weak tunneling, we project onto themost relevant charge states. For strong tunneling, we start from the Andreevfixed point and integrate out charge fluctuations which gives an effectivelow-energy model for the non-perturbative gate-voltage modulated cotunnelingcurrent. In both regimes and in contrast to cotunneling with normal leads, theconductance is temperature independent because of the resonant Andreevreflections, which are included to all orders.
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机译：我们使用低能量描述研究了连接到不同电磁环境的拓扑超导体的电荷传输，其中仅包括超导体中的Majorana束缚态。当环境电阻大于$ 2e ^ 2 / h $时，发现具有电导率$ 2e ^ 2 / h $的完美安德列夫反射与传导受阻的系统之间有交叉的早期发现，我们认为马约拉纳键合状态耦合到金属点。特别是，我们研究了在弱隧穿和强隧穿状态下由金属量子点连接的两个拓扑超导引线。对于弱隧道效应，我们投影到最相关的电荷状态。对于强隧穿，我们从Andreevfixed点开始，并积分电荷波动，从而为非扰动栅极电压调制的共隧道电流提供了有效的低能量模型。在这两种情况下，与与正常引线共隧穿相比，由于谐振安德列夫夫反射（Andreevreflections）都包含在所有阶次中，因此电导与温度无关。
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