Bell Nonlocality and device-independent certification
The "violation of Bell inequalities" is the observation that conclusively proves that the results of some measurements are not pre-established. This foundational observation has an applied side: it can be used to certify quantum devices in a "device-independent" way, that is, without having to describe which measurements are being performed on which physical systems.
Valerio was one of those who first made this observation back in 2007. Since, we have not stopped contributing to this field. After some years helping to certify randomness, we have focused on the remarkable possibility of "self-testing": in some cases, the observation is compatible with a unique quantum description in terms of states and measurements.
In 2019, Valerio has published a reference treatise on Bell Nonlocality.
To learn more:
- Device-independent in general: watch a colloquium talk or study a set of lecture notes.
- Randomness: listen to a 100-second audio, watch the video of a 48-minutes talk, or read one of our papers.
- Theory for experiments: randomness certified by the violation of Bell inequalities with continuous sources.
- Self-testing: watch the video of a 30-minutes talk or read our most famous paper in the field.
This expression usually refers to QKD setups, random number generators, and of course quantum computers. For the study and certification of those, see above. But we are also looking at devices with different functionalities: thermodynamical functionalities (engines and refrigerators), or even quantum replacements for basic optical devices (mirrors, cavities).
To learn more:
- Our models of rotor quantum engines: autonomous (no need of external drive) and with an obvious classical analog that facilitates comparison. The phenomenological notion of work coincides numerically with a notion inspired by quantum information theory.
- We did the theoretical support for the first experimental study of the dynamics of a quantum absorption refrigerator.
- Our theoretical study of a cavity made with quantum mirrors. A mirror here is not just modeled by a boundary condition: its physics matters. In particular the cavity traps light only if the response of the mirrors is faster than the time it takes for the light to propagate in the cavity.
Going to larger systems
This is going to be the focus for the future. The big question is that of the Heisenberg cut: it is really movable at will? And can we contribute to experiments that push quantum coherence towards bigger and bigger systems? These are very ambitious questions. We shall build up from two previous pieces of work:
- Our work on tree size complexity of multiqubit states may be already relevant for NISQ (noisy intermediate-scale quantum computers).
- Our collaboration in the first experimental evidence of Bell-nonlocal correlations in many-atoms systems.