Quantum physics takes on Majorana fermions
Quantum physics boasts many fascinating phenomena that could have an important impact on quantum computing. One of these is Majorana fermions in condensed matter systems, first predicted in the 1930s. More recently, researchers found that some interacting systems in condensed matter physics can produce Majorana fermions in new forms, creating candidate systems known as topological superconductors. This phenomenon is still elusive to physicists, requiring advanced methods to tease out its secrets with the support of non-abelian statistics. To this end, the EU-funded DMMMTS (Detection and manipulation of Majorana modes in topological superconductors) project set out to investigate Majorana fermions and bring them within the fold of universal quantum computation. It conceived a device named Majorana-Transmon qubit that incorporates Majorana quasiparticles into current qubit architectures and exploits their properties to protect quantum information. In order to achieve its aims, the project team identified the electromagnetic properties of the proposed device, pinpointing two very important aspects. The first involves the discovery of a protected doublet that doesn’t stick readily to the electromagnetic environment and protects the qubit from decoherence, despite being open to manipulation. The second is the ability to measure the presence of the Majorana quasiparticles by detecting parity interference phenomena in the microwave absorption spectrum. In parallel, the team was able to identify the presence of Majorana edge states or neutral edge states by exploring thermoelectric effects. It successfully validated a newly conceived method to detect neutral edge states in the quantum Hall regime. Further, researchers explored signatures of the coupling of Majorana fermions to a fermion lead, which also revealed data about the behaviour of Majorana fermions in mesoscopic geometries. One of the main project outcomes involves proving that Majorana quasiparticles retain their unique quantum statistics even when they propagate inside critical systems, independent of their parent superconductor. DMMMTS developed a new method to calculate the adiabatic abelian phase associated with a vortex exchange in p-wave superconductors. This revealed key information on the behaviour of vortices that carry Majorana fermions in topological superconductors. The advances in this field of research bode well for quantum computing.
Keywords
Quantum physics, Majorana fermions, topological superconductors, quantum computing, DMMMTS
