# Erasing odd-parity states in semiconductor quantum dots coupled to superconductors

## TL;DR

This paper investigates how increasing coupling in semiconductor quantum dots with superconductors erases odd-parity states, revealing new transport phenomena and parallels with Majorana nanowires.

## Contribution

It demonstrates the erasure of odd-parity states in quantum dots coupled to superconductors and explains this through competition between Kondo temperature and superconducting gap.

## Key findings

- Odd-parity regimes become indistinct at high and low bias.
- Transport features resemble those of Majorana nanowires.
- Numerical simulations support the experimental observations.

## Abstract

Quantum dots are gate-defined within InSb nanowires, in proximity to NbTiN superconducting contacts. As the coupling between the dot and the superconductor is increased, the odd-parity occupations become non-discernible (erased) both above and below the induced superconducting gap. Above the gap, conductance in the odd Coulomb valleys increases until the valleys are lifted. Below the gap, Andreev bound states undergo quantum phase transitions to singlet ground states at odd occupancy. We observe that the apparent erasure of odd-parity regimes coincides at low-bias and at high-bias. This observation is reproduced in numerical renormalization group simulations, and is explained qualitatively by a competition between Kondo temperature and the induced superconducting gap. In the erased odd-parity regime, the quantum dot exhibits transport features similar to a finite-size Majorana nanowire, drawing parallels between even-odd dot occupations and even-odd one-dimensional subband occupations.