Manipulating Majorana zero modes in double quantum dots

Abstract

Majorana zero modes (MZMs) emerging at the edges of topological\nsuperconducting wires have been proposed as the building blocks of novel,\nfault-tolerant quantum computation protocols. Coherent detection and\nmanipulation of such states in scalable devices are, therefore, essential in\nthese applications. Recent detection proposals include semiconductor quantum\ndots (QDs) coupled to the end of these wires, as changes in the QD electronic\nspectral density due to the MZM coupling could be detected in transport\nexperiments. Here, we propose that multi-QD systems can also be used to\nmanipulate MZMs through precise control over the QDs' parameters. The simplest\ncase where Majorana manipulation is possible is in a double quantum dot (DQD)\ngeometry. By using exact analytical methods and numerical renormalization-group\ncalculations, we show that the QDs' spectral functions can be used to\ncharacterize the presence or not of MZMs "leaking" into the DQD. More\nimportantly, we find that these signatures respond to changes in the DQD\nparameters such as gate-voltages and couplings in a consistent fashion.\nAdditionally, we show that different MZM-DQD coupling geometries ("symmetric" ,\n"in-series" and "T-shaped" junctions) offer distinct ways in which MZMs can be\nswitched from dot to dot. These results highlight the interesting possibilities\nthat DQDs offer for all-electrical MZM control in scalable devices.\n