(Invited) Bottom-up Grown Nanowire Quantum Devices

Abstract

The main challenge for the development of a quantum computer is to solve decoherence. The promise of topological quantum computation is that local noise does not affect and destroy the quantum state, and therefore long coherence times are expected. In a topological system the quantum information is encoded in quasi particles, called Majorana Zero Modes (MZM). First signatures of MZM have been obtained in InSb nanowires [1]. Recently, different schemes for performing logical operations and uncovering the properties of Majorana states are proposed. For such a universal computational architecture the realization of a near-perfect nanowire network assembly is needed in which Majorana states are coherently coupled. Here, we demonstrate a generic process by which we can design any proposed braiding device by manipulating an InP substrate and thereby the nanowire growth position and orientation [2]. Our method leads to highly controlled growth of InSb nanowire networks with single crystalline wire-wire junctions. Additionally, nanowire “hashtag” structures are grown with a high yield and contacted. In these devices, the Aharonov–Bohm (AB) effect is observed, demonstrating phase coherent transport. These measurements reveal the high quality of these structures. Furthermore, this platform is used for in-situ epitaxial shadow growth of a superconductor on the nanowire facets, resulting in transport contacts. With this new generation devices we have observed quantized MZM [3]. Mourik et al., Science 2012, 336, 1003Gazibegovic et al. Nature 548 2017, 434Zhang et al. Nature 2018 , accepted