Speaker
Dr
Christophe Mora
(Ecole Normale Supérieure, France)
Description
Abstract: We propose a device architecture with Majorana
fermions predicted to host a manifold of non-Fermi
quantum impurity states. The device consists of a floating
superconducting island carrying one-dimensional nanowires
with Majorana end states. The Majorana are tunnel-coupled
to normal leads while the island is Josephson-coupled to a
bulk superconductor. In this system, the quantum impurity,
nonlocally encoded by the Majorana fermions, experiences
both Kondo screening and resonant Andreev reflection
processes. Surprisingly, we found that these two effects can
coexist, leading to a ground state manifold with non-Fermi
liquid continuous exponents. Our results were obtained
using a combination of conformal field theory arguments,
Abelian bosonization and an intuitive quantum Brownian
motion analogy which explains the manifold in simple
terms. We also found an illuminating analogy between our
system and the two-channel two-impurity Kondo model.
The predicted manifold and its non-Fermi liquid nature can
be identified in charge transport measurements, where we
predict the appearance of nonlocal conductances with a
power law temperature dependence. The power law
exponent is continuously tunable within the manifold by
changing gate voltages.
