Swapping and entangling hyperfine coupled nuclear spin baths

TL;DR

This study demonstrates the potential to swap and entangle nuclear spin baths in coupled quantum dots, highlighting their usefulness for quantum information processing and how system geometry influences dynamics.

Contribution

It introduces a numerical model showing nuclear bath swapping and entanglement in quantum dots, emphasizing the role of bath size and geometry.

Findings

Nuclear baths can be swapped on second timescales.

Full entanglement of nuclear baths is potentially achievable.

Larger baths enhance their utility for quantum information.

Abstract

We numerically study the hyperfine induced nuclear spin dynamics in a system of two coupled quantum dots in zero magnetic field. Each of the electron spins is considered to interact with an individual bath of nuclear spins via homogeneous coupling constants (all coupling coefficients being equal). In order to lower the dimension of the problem, the two baths are approximated by two single long spins. We demonstrate that the hyperfine interaction enables to utilize the nuclear baths for quantum information purposes. In particular, we show that it is possible to swap the nuclear ensembles on time scales of seconds and indicate that it might even be possible to fully entangle them. As a key result, it turns out that the larger the baths are, the more useful they become as a resource of quantum information. Interestingly, the nuclear spin dynamics strongly benefits from combining two quantum dots of different geometry to a double dot set up.