The peculiar kind of correlations that quantum systems can exhibit, and in particular quantum entanglement, is one of many aspects that differentiate quantum mechanics from classical mechanics. Such non-classical aspects are interesting both from a fundamental point of view and from a practical point of view. On one hand, we want to understand better how nature works, particularly going beyond our intuitive “classical” view of the world. On the other hand, non-classical properties can be exploited in quantum information processing (QIP) and quantum technologies.
The project aimed at characterizing and exploiting the quantum properties and behaviour – or, we will write in short, the “quantumness” – of correlated systems.
The project focused on obtaining a picture of quantum correlations and quantumness as unified and as operational as possible. By “operational” picture, we mean in particular that we aimed at characterizing quantum properties in terms of tasks for which quantum properties allow, e.g. to outperform the corresponding “classical” case, and in ways that may lead to direct and accessible experimental verification. Specifically, the project was based on the following three main approaches to the characterization of correlations:
- The consideration of the role of quantum correlations in the discrimination of physical processes;
- The development of tool and concepts related to the expression of quantum states of bipartite systems in a standard form;
- The view of correlations as resources under appropriate limitations in their manipulation.
We also aimed at understanding and verifying quantum correlations in concrete physical scenarios, like the ones encountered in atomic physics and quantum optics.
The action successfully:
- Proved that, the more a bipartite state is entangled, the more useful is it in the discrimination of physical processes
- Developed conceptual and quantitative tools for the quantification of the degree of correlations present in a bipartite quantum state, as well as its usefulness for discriminating any two arbitrary physical evolutions; this was based on a standard and convenient decomposition of bipartite quantum states
- Developed conceptual and quantitative tools for the quantification of the entanglement of identical particles; this is in particular relevant for experiments dealing with either fermions or bosons
- Developed conceptual and quantitative tools, based on the task of phase discrimination, for the quantification of general quantum coherence
- Provided further evidence that quantum coherence and quantum entanglement are deeply interrelated concepts, and provided ways to map the study of the former into the latter, also considering a many-body scenario
- Investigated the role of energy in the discrimination of physical processes; we introduced quantifiers of how different two physical processes are that depend on the amount of energy at disposal for the verification of such a difference
- Developed tools for the quantification of a quantumness of correlations that is more general than entanglement
