Search query: "Panagiotis Kotetes"

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abstract: Hybrid superconductor semiconductor devices are currently one of the most promising platforms for realizing Majorana zero modes. Their topological properties are controlled by the band alignment of the two materials, as well as the electrostatic environment, which are currently not well understood. Here, we pursue to fill in this gap and address the role of band bending and superconductor semiconductor hybridization in such devices by analyzing a gated single Al InAs interface using a self consistent Schrodinger Poisson approach. Our numerical analysis shows that the band bending leads to an interface quantum well, which localizes the charge in the system near the superconductor semiconductor interface. We investigate the hybrid band structure and analyze its response to varying the gate voltage and thickness of the Al layer. This is done by studying the hybridization degrees of the individual subbands, which determine the induced pairing and effective $g$ factors. The numerical results are backed by approximate analytical expressions which further clarify key aspects of the band structure. We find that one can obtain states with strong superconductor semiconductor hybridization at the Fermi energy, but this requires a fine balance of parameters, with the most important constraint being on the width of the Al layer. In fact, in the regime of interest, we find an almost periodic dependence of the hybridization degree on the Al width, with a period roughly equal to the thickness of an Al monolayer. This implies that disorder and shape irregularities, present in realistic devices, may play an important role for averaging out this sensitivity and, thus, may be necessary for stabilizing the topological phase.
author_names: August E G Mikkelsen

Panagiotis Kotetes

Peter Krogstrup

Karsten Flensberg
title: Hybridization at Superconductor Semiconductor Interfaces
year: 2018

abstract: We demonstrate how to design various nonstandard types of Andreev bound state (ABS) dispersions, via a composite construction relying on Majorana bound states (MBSs) Here, the MBSs appear at the interface of a Josephson junction consisting of two topological superconductors (TSCs) Each TSC harbors multiple MBSs per edge by virtue of a chiral or unitary symmetry. We find that, while the ABS dispersions are 2p periodic, they still contain multiple crossings which are protected by the conservation of fermion parity. A single junction with four interface MBSs and all MBS couplings fully controllable, or networks of such coupled junctions with partial coupling tunability, open the door for topological band structures with Weyl points or nodes in synthetic dimensions, which in turn allow for fermion parity (FP) pumping with a cycle set by the ABS dispersion details. In fact, in the case of nodes, the FP pumping is a manifestation of chiral anomaly in 2D synthetic spacetime. The possible experimental demonstration of ABS engineering in these devices further promises to unveil new paths for the detection of MBSs and higher dimensional chiral anomaly.
author_names: Panagiotis Kotetes

M T Mercaldo

M Cuoco
title: Synthetic Weyl Points and Chiral Anomaly in Majorana Devices with Nonstandard Andreev Bound State Spectra.
venue: Physical review letters
year: 2019

abstract: We demonstrate how to design various nonstandard types of Andreev bound state (ABS) dispersions, via a composite construction relying on Majorana bound states (MBSs) Here, the MBSs appear at the interface of a Josephson junction consisting of two topological superconductors (TSCs) Each TSC harbors multiple MBSs per edge, by virtue of a chiral or unitary symmetry. We find that, while the ABS dispersions are $2\pi$ periodic, they still contain multiple crossings which are protected by the conservation of fermion parity. Considering networks of coupled junctions of this type, opens the door for topological bandstructures with nodes or Weyl points in synthetic dimensions, and the realization of chiral anomaly. The latter, also allows for fermion parity pumping with a cycle set by the ABS dispersion details. The possible experimental demonstration of ABS engineering in these devices, will further unveil new paths for the detection of chiral anomaly and MBSs.
author_names: Panagiotis Kotetes

M T Mercaldo

M Cuoco
title: Nonstandard Andreev Bound State Spectra in Majorana Devices and Chiral Anomaly Phenomena in Synthetic Dimensions
year: 2019

author_names: Panagiotis Kotetes
title: Topological insulators in 1+1 dimensions
year: 2019

author_names: Panagiotis Kotetes
title: Topological classification of insulators and beyond
year: 2019

author_names: Panagiotis Kotetes
title: Z2 topological insulators
year: 2019

author_names: Panagiotis Kotetes
title: Symmetries and effective Hamiltonians
year: 2019

author_names: Panagiotis Kotetes
title: Chern insulators applications
year: 2019

author_names: Panagiotis Kotetes
title: Electron coupling to external fields and transport theory
year: 2019

author_names: Panagiotis Kotetes
title: Chern insulators fundamentals
year: 2019