Topological Superconductivity in Chiral Carbon Nanotubes: Superconducting Diode Effects

Topological superconductivity (TSC) has been intensively investigated over the past decades, but difficulties in pinning down TSC phases has called for novel experiments. To this end, the superconducting diode effect (SDE) has attracted interest in recent years as a way to shed light on TSC but also to enable a number of applications. In this talk, we will present analytic and numerical results on the SDE in chiral carbon nanotubes (CNTs). We find that chiral nanotubes in Josephson junctions can exhibit large diode efficiencies far exceeding those of superconducting chiral nanotubes when an external magnetic field is applied along the nanotube. Furthermore, our numerical simulations show that the Josephson diode polarity can be tuned by electrostatically gating CNTs in a Josephson junction. Lastly, we will discuss the diode effect as a superconducting CNT is tuned into a TSC phase and the role of chirality in this case.