We propose the implementation of the Swap Test using a charge qubit in a double quantum dot. The Swap Test is a fundamental quantum subroutine in quantum machine learning and other applications for estimating the fidelity of two unknown quantum states by measuring an auxiliary qubit. Our proposal uses a controlled three-qubit gate which is natural to quantum-dot charge qubits. It allows us to implement a Swap Test with a circuit depth of six layers, and an estimated gate time of less than 3 ns, that is below the coherence time of double quantum dots. This work paves the way for enhancing the toolbox of quantum machine learning developments in semiconductor qubits.
@article{arxiv.2112.15517,
title = {Swap Test with Quantum-Dot Charge Qubits},
author = {Y. -D. Li and N. Barraza and G. Alvarado Barrios and E. Solano and F. Albarrán-Arriagada},
journal= {arXiv preprint arXiv:2112.15517},
year = {2022}
}