# Spectroscopy of double quantum dot two-spin states by tuning the inter-dot barrier

## TL;DR

This paper demonstrates that tuning the inter-dot tunnel barrier with an AC electric field significantly enhances transition rates and multi-photon resonances in double quantum dot two-spin states, enabling faster spin transitions.

## Contribution

It introduces a novel method of tuning the inter-dot barrier to improve transition rates and resonance effects in double quantum dot systems.

## Key findings

- Transition rate increases drastically at large detuning when tuning the barrier.
- Multi-photon resonances are enhanced by orders of magnitude.
- The method enables faster two-spin transitions.

## Abstract

Transport spectroscopy of two-spin states in a double quantum dot can be performed by an AC electric field which tunes the energy detuning. However, a problem arises when the transition rate between the states is small and, consequently, the AC-induced current is suppressed. Here, we show that if the AC field tunes the inter-dot tunnel barrier then for large detuning the transition rate increases drastically resulting in high current. Multi-photon resonances are enhanced by orders of magnitude. Our study demonstrates an efficient way for fast two-spin transitions.