# Quantum dot state initialization by control of tunneling rates

## TL;DR

This paper presents a method for controlling and measuring tunneling rates in quantum dots to efficiently initialize specific electron spin states, advancing quantum technology applications.

## Contribution

It introduces a technique to measure individual tunneling rates and selectively load quantum dot states by tuning energy and tunneling parameters.

## Key findings

- Selective loading into specific quantum dot states achieved.
- Triplet-to-singlet relaxation is suppressed, enabling stable spin states.
- Fast initialization of electron pairs with controlled spin states.

## Abstract

We study the loading of electrons into a quantum dot with dynamically controlled tunnel barriers. We introduce a method to measure tunneling rates for individual discrete states and to identify their relaxation paths. Exponential selectivity of the tunnel coupling enables loading into specific quantum dot states by tuning independently energy and rates. While for the single-electron case orbital relaxation leads to fast transition into the ground state, for electron pairs triplet-to-singlet relaxation is suppressed by long spin-flip times. This enables the fast gate-controlled initialization of either a singlet or a triplet electron pair state in a quantum dot with broad potential applications in quantum technologies.