Majorana拓扑量子计算，无疑是当前拓扑凝聚态物理及其应用研究中最令人感兴趣的内容之一。本项目将对拓扑量子计算中的量子测量和退相干问题开展以下研究：1）研究Majorana量子比特“逻辑Z算符”的测量，包括在多态情况下对等效Z算符的可靠性检验、准粒子污染、环境电荷1/f噪声等退相干效应，给出测量信号对比度和量子效率的刻画，并建立“部分坍缩”测量的量子贝叶斯理论。 2）开展Majorana量子比特相干振荡的测量研究，包括“X旋转”方案、环境噪声与量子比特电偶极矩相互作用导致的准粒子激发效应，以及如何提取退相干参数、进而澄清退相干机理。 3）研究Majorana表面码中稳定子的测量方案，特别包括利用宇称联合测量移动逻辑比特、实现辫子操作和量子逻辑门，并结合实际因素研究信号对比度、信息读取时间、以及各种耦合强度的优化。

The robustness of being immune from local noise has made the Majorana-zero-modes (MZM) based topological quantum computation a frontier of research attracting great attentions. The proposed project is planned to carry out a deep and systematic investigation for the decoherence and quantum measurement of the 4-MZM based qubit system: (i) Construct the measurement scheme (including partial-collapse measurement) of the logic Z-operator and examine the reliability of the effective description through a full multi-state simulation, and as well analyze the various decoherence effects manifested in such quantities as the signal-to-noise ration and quantum efficiency. (ii) Study the measurement of coherent oscillations of the 4-MZM qubit, including designing the coupling for unitary rotations and analyzing the decoherence caused by the interaction of the electric-dipole with the environmental charge noise (1/f noise). (iii) Study the measurement of stabilizers in the Majorana surface code, including proper construction of the measurement schemes, real effects, and joint-parity measurement of multiple qubits and its applications in realizing universal quantum logic gates.