Topological quantum computation based on chiral Majorana fermions

TLDR

Chiral Majorana fermions are massless self‑conjugate edge states of certain two‑dimensional topological materials, while their bulk counterparts, Majorana zero modes, are known to enable topological quantum computation. The authors demonstrate that chiral Majorana fermion propagation implements the same unitary transformations as braiding Majorana zero modes, proposing a new platform for quantum computation. They use a Corbino‑ring junction of the hybrid device to harness coherent chiral Majorana fermions for implementing Hadamard and phase gates, with junction conductance providing qubit readout. The hybrid quantum anomalous Hall insulator–superconductor device has been predicted and observed to host chiral Majorana fermions, which the authors show can realize Hadamard and phase gates with conductance‑based readout.

Abstract

Chiral Majorana fermion is a massless self-conjugate fermion which can arise as the edge state of certain two-dimensonal topological matters. It has been theoretically predicted and experimentally observed in a hybrid device of quantum anomalous Hall insulator and a conventional superconductor. Its closely related cousin, Majorana zero mode in the bulk of the corresponding topological matter, is known to be applicable in topological quantum computations. Here we show that the propagation of chiral Majorana fermions lead to the same unitary transformation as that in the braiding of Majorana zero modes, and propose a new platform to perform quantum computation with chiral Majorana fermions. A Corbino ring junction of the hybrid device can utilize quantum coherent chiral Majorana fermions to implement the Hadamard gate and the phase gate, and the junction conductance yields a natural readout for the qubit state.