Ricerc@Sapienza

In the last decades, an increasing interest in quantum technologies has brought to the flourishing of many theoretical and experimental protocols which exploit quantum resources. Indeed, some fundamental properties of quantum mechanics, e.g. entanglement and superposition principle, are widely believed to allow improvements in several fields, as for example in communication, cryptographic protocols, randomness extraction and quantum computation. However, all these tasks require the use of genuinely quantum states and measurements. Hence, the necessity to study protocols to discern devices that are truly exploiting quantum resources from those that do not. Furthermore, it would be desirable to perform such a distinction, without knowing in detail the internal functioning of the adopted device, which can be hard or impossible to verify. Such an approach is known as "device-independent".

In this context, causal inference, or the quantification of causal relationships among phenomena, turns out to be extremely useful. Indeed, causal inference allows to verify whether a device is correctly implementing the desired causal structure, i.e. a scheme of cause-effect relations among variables, just by observing its input/output statistics (i.e. device-independently). Then, the discrepancies between classical and quantum causal predictions can be used to detect the presence of quantum effects, within a given causal structure.

The aim of this project is precisely to find such discrepancies and exploit them to detect the presence of a quantum signature within a given causal structure, thus allowing a deeper knowledge of quantum processes and, consequently, a stronger control on future applications in the field of device-independent certification protocols for quantum communication and computation.