Majorana fermions (MFs) are a theoretical particle which, unlike conventional fermions, act as their own antiparticle. The non-abelian nature of these particles means than the physical action of braiding one MF around another imparts a non-trivial phase. A recent condensed matter realisation of these particles was suggested by Kitaev whereby MFs would exist at the ends of superconducting nanowires. If information were to be encoded in such a system it would be topologically protected from noise, as a global perturbation would be required to destroy it. Systems with such a topological protection are therefore highly sought after for computing and information storage purposes.
The primary signature of the existence of MFs in superconducting nanowires is a zero bias conductance (ZBC) feature in the transport response of the wires. However there are several alternative explanations for such a feature which can cast doubt over the origin of the ZBC observed in experiment. Therefore the development of a method for distinguishing systems which definitively contain MBS from other topologically trivial effects is highly important. To this end we are exploring circuit geometries which are capable of hosting Majorana fermions at the superconducting/normal interfaces within the circuit. A computational model for these unique geometries allows us to study the interplay between MBS and the interference effects induced applied by magnetic fields.
Our study begins by computationally examining a ring comprised of two Kitaev chains with a normal conducting links between them where the MFs form at the normal/superconducting interfaces. An applied magnetic field induces Aharonov-Bohm interference due to path differences around the ring. This allows for an analysis of signatures of MFs as a function of the magnitude and direction of an applied magnetic field. Further, we also look at the influence of disorder on the transport signals in such a system. This computational model can inform future experiments which probe the topological properties of Majorana fermions.
About the presenter
Tommy is a PhD student and condensed matter theoretical physicist at RMIT university under the supervision of Jared Cole. Within FLEET he works in Research theme 1: topological materials.