Machine-learning-based device-independent certification of quantum networks

Witnessing nonclassical behavior is a crucial ingredient in quantum information processing. For that, one has to optimize the quantum features a given physical setup can give rise to, which is a hard computational task currently tackled with semidefinite programming, a method limited to linear objective functions and that becomes prohibitive as the complexity of the system grows. Here, we propose an alternative strategy, which exploits a feedforward artificial neural network to optimize the correlations compatible with arbitrary quantum networks. A remarkable step forward with respect to existing methods is that it deals with nonlinear optimization constraints and objective functions, being applicable to scenarios featuring independent sources and nonlinear entanglement witnesses. Furthermore, it offers a significant speedup in comparison with other approaches, thus allowing to explore previously inaccessible regimes. We also extend the use of the neural network to the experimental realm, a situation in which the statistics are unavoidably affected by imperfections, retrieving device-independent uncertainty estimates on Bell-like violations obtained with independent sources of entangled photon states. In this way, this work paves the way for the certification of quantum resources in networks of growing size and complexity.

Automated summary

In this research, an alternative strategy is proposed to optimize correlations compatible with arbitrary quantum networks using a feedforward artificial neural network. Compared to existing methods, this method handles problems with nonlinear optimization constraints and objective functions and is more efficient than other approaches, allowing exploration of previously inaccessible areas. In addition, the neural network is extended to the experimental field to obtain device-independent uncertainty estimates on Bell-like violations obtained with independent sources of entangled photon states. This research paves the way for certifying quantum resources in networks of growing size and complexity.