New Journal of Physics 21, 043027 (2019)
Transport signatures of a Majorana qubit and read-out-induced dephasing
Lupei Qin1,2, Xin-Qi Li2, Alexander Shnirman3,4 and Gerd Schön1,5
1 Institut für Theoretische Festkörperphysik, Karlsruhe Institute of Technology (KIT), D-76131 Karlsruhe, Germany
2 Center for Joint Quantum Studies, School of Science, Tianjin University, 300072, People's Republic of China
3 Institut für Theorie der Kondensierten Materie, Karlsruhe Institute of Technology (KIT), D-76131 Karlsruhe, Germany
4 Institut für Nanotechnologie, Karlsruhe Institute of Technology (KIT), D-76021 Karlsruhe, Germany
5 Author to whom any correspondence should be addressed.
Motivated by recent proposals of Majorana qubits and the read-out of their quantum state we investigate a qubit setup formed by two parallel topological wires shunted by a superconducting bridge. The wires are further coupled to two quantum dots, which are also linked directly, thus creating an interference loop. The transport current through this system shows an interference pattern which distinguishes two basis states of the qubit in a QND measurement. We analyze various properties of the interference current and the read-out process, including the resulting dephasing and relaxation. We also analyze the effects of varying control parameters such as gate voltages on the current. The characteristic dependencies may serve as a signature of Majorana bound states.
Keywords: Majorana qubit, quantum master equation, quantum measurement, dephasing