IMX Seminar Series - Building a materials platform to support topological quantum computing

Philippe Caroff et al., Microsoft Quantum Lab Delft, The Netherlands.  Nanoscale hybrid III-V semiconductor/superconductor heterostructures are promising for advanced quantum transport physics, in particular as hosts to Majorana quasiparticles. Most work in the field has relied on Vapor-Liquid-Solid grown InAs or InSb nanowires, which require one-by-one manual placement to enable device fabrication, and are therefore inadequate for scaling-up. Selective-area epitaxy is promising as a scalable materials platform combining advantages of both VLS nanowires and planar 2DEG (along with some of their challenges), and will be the central topic of this presentation. We’ll start with a broad context of quantum computing and the original path presented by topological quantum computing, finishing with the list of key ingredients theory as well as fabrication requests from the materials platform. The chosen selective area epitaxy technique will be introduced from historic early steps using favorable metalorganic vapour phase or chemical beam epitaxy (MOVPE/CBE) to most recent renewed interests in the challenging case of atomic or molecular species “precursors” in the molecular beam epitaxy technique (MBE). An in-situ methodology to map the parameter space for selectivity will be introduced. We’ll then review growth and architecture rules for satisfactory in-plane nanowire networks based on simple crystallographic, nucleation kinetics and polarity arguments. Finally, we’ll demonstrate promises of the high spin-orbit coupling InSb/Al SAG system via structural and transport characterization and discuss the future challenges for a scalable quantum materials platform.
Bio: Philippe Caroff obtained his Ph.D. degree in physics in 2005 from the Institut National des Sciences Appliqués (INSA Engineering School) in Rennes (France) on growth of III-V quantum dots for telecom applications, and was a postdoctoral scholar in Lund University from 2006 to 2008 on III-V nanowires. He became a tenured CNRS Research Scientist in 2008 and worked in Lille (IEMN), France, for four years on MBE growth of III-V nanowires, before joining the Australian National University (ANU), Department of Electronic Materials Engineering, in 2013 as an independently funded Australian Research Council Future Fellow. He joined Cardiff University and the newly created Institute for Compound Semiconductors (ICS), UK, in December 2016, to serve as Sêr Cymru Senior Research Fellow and MBE lab facility manager. Since December 2017, he works at Microsoft Quantum Lab Delft, The Netherlands. The focus of his team of material scientists is on growth of hybrid III-V/superconductor nano-heterostructures to support progress on topological quantum computing.