SuperDirac: Controllable topological superconductivity in a Dirac semimetal

Summary

A crucial problem in the construction of a large, many-qubit quantum computer is quantum decoherence: A physical system will remain in a coherent superposition of states only for a finite (short) time. The conventional solution is quantum error correction which minimizes or eliminates errors as long as decoherence is sufficiently weak. It is similar in spirit to the error correction in a classical, digital computer. Another approach, topological quantum computation, makes the system immune to the usual sources of quantum decoherence due to its topological protection.
Topological superconductors form one of the most promising systems. So far, only a few groups in the world have experimentally shown signatures of topological superconductivity in different materials. Recently, my research at the University of Twente has led to the first realization of topological superconductivity in a 3D Dirac semimetal (Bi0.97Sb0.03) by means of the proximity effect and its topological nature is revealed by observing Majorana zero energy modes (which are the condensed matter analogue of the hypothesized Majorana fermions known from high-energy physics, basic elements for topological quantum computing devices).
It is the objective of this proposal to realize controllable topological superconducting devices and to demonstrate the interchange of two Majorana states (braiding), as the most basic topological quantum operation. In this project, I will first integrate the Dirac semimetal junctions into an asymmetric superconducting quantum interference devices (SQUIDs), in order to study the current-phase relation and the stability of the Majorana states. Then, a spectroscopy measurement will be carried out to demonstrate the phase-driven braiding of Majorana quasiparticles.
My expertise in nanofabrication and quantum transport measurements with relevant materials as well as my international collaborations with different laboratories, promise a head start for this project. Together with the state-of-the-art nanotechnology facilities at the University of Twente, all conditions are met to pursue the long-desired Majorana braiding.

Details

Project number

680-47-463

Main applicant

Dr. C. Li

Affiliated with

Universiteit Twente, MESA+ Research Institute for Nanotechnology, Transducers Science and Technology (TST)

Duration

01/11/2017 to 04/09/2020