Condensed Matter Seminar: Synthetic Majorana Zero Modes in Cold Atomic Systems

Abstract:

Recent experimental advances in the field of cold atoms led to the development of novel techniques for producing synthetic dimensions and synthetic gauge fields, thus greatly expanding the utility of cold atomic systems for exploring exotic states of matter. 

I will discuss the possibility of mimicking the physics of Majorana chains in cold atomic systems with conserved number of particles.

Crucially to our proposal, the interactions between particles can be tuned. While they are local in space, they appear non-local in the synthetic dimension. We use this fact to induce coupling between ``synthetic'' counter-propagating edge modes in the quantum Hall regime. For the case of attractive interactions in a system composed of two tunneling-coupled chains, we find a gapless quasi-topological phase with a doubly-degenerate ground state. While the total number of particles in the system is kept fixed, this phase is characterized by strong fluctuations of the pair number in each chain. Each ground state is characterized by the parity of the total particle number in each chain, similar to Majorana wires. 

However, in our system this degeneracy persists for periodic boundary conditions. For open boundary conditions there is a small splitting of this degeneracy due to the single-particle hopping at the edges. I will discuss how to control this non-local qubit by subjecting the system to additional synthetic flux.

Event Organizer: Prof. Eran Sela