Kavli Affiliate: Michael Wimmer
| First 5 Authors: Sebastian Miles, David van Driel, Michael Wimmer, Chun-Xiao Liu,
| Summary:
We propose to implement a Kitaev chain based on an array of alternating
normal and superconductor hybrid quantum dots embedded in semiconductors. In
particular, the orbitals in the dot and the Andreev bound states in the hybrid
are now on equal footing and both emerge as low-energy degrees of freedom in
the Kitaev chain, with the couplings being induced by direct tunneling. Due to
the electron and hole components in the Andreev bound state, this coupling is
simultaneously of the normal and Andreev types, with their ratio being tunable
by varying one or several of the experimentally accessible physical parameters,
e.g., strength and direction of the Zeeman field, as well as changing proximity
effect on the normal quantum dots. As such, it becomes feasible to realize a
two-site Kitaev chain in a simple setup with only one normal quantum dot and
one hybrid segment. Interestingly, when scaling up the system to a three-site
Kitaev chain, next-nearest-neighbor couplings emerge as a result of high-order
tunneling, lifting the Majorana zero energy at the sweet spot. This energy
splitting is mitigated in a longer chain, approaching topological protection.
Our proposal has two immediate advantages: obtaining a larger energy gap from
direct tunneling and creating a Kitaev chain using a reduced number of quantum
dots and hybrid segments.
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