Josephson Diode Effect in Chiral Carbon Nanotubes

Within superconducting electronics, the Josephson diode effect (JDE) has attracted interest in recent years. Josephson diodes are characterized by an asymmetry in positive and negative switching currents of a Josephson junction (JJ) and could potentially find utility in a growing number of applications at cryogenic temperatures in the Quantum Information Sciences. Despite extensive theoretical and experimental work investigating the JDE, little attention has been paid to nanotube devices where non-reciprocity can be introduced in chiral structures. In this talk, we will present analytic and numerical results on the JDE in chiral carbon nanotubes (CNT). We find that chiral nanotubes in JJs can exhibit diode efficiencies far exceeding those of superconducting chiral nanotubes when an external magnetic field is applied along the nanotube. Furthermore, our numerical simulations show the Josephson diode <i>polarity</i> can be tuned by electrostatically gating CNTs in a Josephson junction. We will discuss the microscopic details that give rise to large diode efficiencies and gate-tunability in chiral CNT JJs.<br/><br/>This work was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), under Award DE-SC0022245. The work at Sandia is supported by a LDRD project. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.