Supercurrent in a quantum dot–Majorana hybrid Josephson junction

How Majorana zero modes (MZMs) influence the Josephson transport is of fundamental importance for the detection of Majorana physics. In this work, we study the supercurrent transport through a quantum dot–MZM hybrid Josephson junction within the framework of Keldysh non-equilibrium Green’s function. The density of states with and without MZMs is discussed. The effects of quantum dot level, Majorana overlap, spin-dependent coupling, and Majorana nonlocality on the supercurrent transport properties are analyzed. Without Majorana states, the supercurrent exhibits a conventional 2π-periodic pattern. Finite Majorana overlap and asymmetric coupling trigger a 0 − π transition as well as a 2π-to-4π periodicity transition. Moreover, the nonlocality quality factor can strongly reshape the supercurrent line shape. We elucidate the underlying physical mechanisms in detail. Our results reveal unambiguous transport signatures for identifying Majorana states and offer insights for manipulating MZMs in topological quantum devices.