Entanglement generation between distant nuclear ensembles in quantum dots

Entanglement is an important resource for quantum information processing applications. We propose a protocol for the deterministic generation of entanglement between two ensembles of nuclei surrounding two distant quantum dots which are connected via an electronic bus. The protocol relies on the injection of electrons with definite polarization in each quantum dot and the coherent transfer of electrons from one quantum dot to the other. Two different regimes are of potential interest to apply our scheme: On the one hand, the large nuclear ensembles that appear in QDs fabricated with GaAs, InGaAs, and ²⁹Si-rich Si, with a number of nuclei ranging from 100 to 10⁶; on the other, nuclear ensembles with just a few nuclei (< 10) that appear, for example, in purified Si. As we show, our protocol is able to produce stable entanglement in both settings, and it is robust against inhomogeneities and imperfections in the protocol execution. We also discuss how to detect the entanglement experimentally using different entanglement witnesses suitable for each case. Recent experimental developments [1, 2] suggest that our proposal could be implemented in the near term.

[1] arXiv:2008.09541 [quant-ph] (2020)
[2] Nature Nanotechnology 15, pages13–17 (2020)