Topological Quantum Wire Emulators

Abstract

Relativistic quantum mechanics dictates that for each type of particle there should exist an antiparticle. For example, a positively charged positron is an antiparticle of a negatively charged electron. There also exists a theoretical possibility of a particle that is its own antiparticle – known as the Majorana fermion after Ettore Majorana's work in the 1930's. Such hypothetical elementary particle has been actively searched for in the context of neutrino physics, supersymmetry, and dark matter but it remains elusive. Alternative ideas have been put forward in condensed matter physics community in the past few years, showing that rather than being discovered blindly in nature, Majoranas can be engineered in transistor-like devices as quasi-particles, which are the collective modes of electrons similar to waves on water. The path of Majorana’s ideas through these different fields of physics has been reviewed by Nobel laureate Frank Wilczek in a popular article ‘Majorana returns’ (Nature Physics, 2009). The rapidly expanding race for Majorana quasi-particles is motivated not only by their fundamental importance, but also by the promise of topological quantum computing. The most prominent approach, ‘a Kitaev chain’, prescribes how to generate Majoranas in a chain of atoms paired into an exotic topological superconductor. This project will explicitly realize a Kitaev chain following an approach that draws from two physics research fronts: ultracold atomic gases and semiconductor nanoelectronics. We will build a chain of artificial atoms (quantum dots) in a semiconducting nanowire, and map the Kitaev model onto our solid state quantum emulator. The sizes of artificial atoms and their coupling strength will be fully tunable making our emulator a powerful platform for studying not only Majorana particles, but beyond, for discovery of currently unknown fundamental topological phases of matter.

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