Geometry of sequential quantum correlations and robust randomness
certification
- URL: http://arxiv.org/abs/2309.12286v1
- Date: Thu, 21 Sep 2023 17:50:29 GMT
- Title: Geometry of sequential quantum correlations and robust randomness
certification
- Authors: Matteo Padovan, Giulio Foletto, Lorenzo Coccia, Marco Avesani, Paolo
Villoresi, Giuseppe Vallone
- Abstract summary: We study the geometry of quantum correlations and their implications for robust device-independent randomness generation.
We identify a boundary for the set of these correlations expressed as a trade-off between the amount of nonlocality between different observers.
We propose a practical protocol based on non-projective measurements that can produce the boundary correlations under ideal conditions.
- Score: 0.0
- License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
- Abstract: Quantum correlations between the measurements of two or more separated
observers play a fundamental role in many applications, such as randomness
generation or key distribution. Recently, it was realized that sequential
measurements (i.e., defined with a precise temporal ordering between subsequent
measurements on a given system) can enhance the performance of these protocols.
However, the theoretical understanding of how to maximize this performance is
limited and the relation with the boundary of quantum correlations is
unexplored. In the case of one party on one side and two sequential parties on
the other, we study the geometry of quantum correlations and its implications
for robust device-independent randomness generation. We identify a boundary for
the set of these correlations expressed as a trade-off between the amount of
nonlocality between different observers and show that this allows to generate
the maximum possible device-independent randomness in our setting, namely two
bits. We propose a practical protocol based on non-projective measurements that
can produce the boundary correlations under ideal conditions, and address its
robustness to noise, showing that it is improved compared to previous
approaches. Finally, we implement our protocol in a proof-of-concept experiment
based on a photonic implementation. With the obtained correlations we could
certify more bits per state with respect to the standard CHSH protocol, proving
that our protocol is feasible and robust to real-world imperfections. Our work
paves the way for a full understanding of sequential quantum correlations and
their exploitation for practical and efficient device-independent protocols.
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