Unitary Subharmonic Response of Floquet Majorana Modes

Abstract

Detection and manipulation of Majorana fermions are essential for creating a topological quantum computer. To this end, we show that unpaired Majorana modes in Floquet systems can directly be visualized using the phenomenon of unitary subharmonic response. Namely, starting from highly non-equilibrium initial states, the unpaired Majorana modes exhibit boundary oscillations that have twice the driving period, are localized, and have up to exponentially long lifetimes with respect to the system's parameters. While the lifetime is still limited in translationally invariant systems, we show how disorder can be engineered to stabilize the subharmonic response of Majorana modes. We also suggest a viable implementation in modern multiqubit systems, such as superconducting circuits and atomic systems.