Genuine multipartite nonlocality with causal-diagram postselection
- URL: http://arxiv.org/abs/2104.10069v3
- Date: Tue, 26 Jul 2022 10:37:00 GMT
- Title: Genuine multipartite nonlocality with causal-diagram postselection
- Authors: Valentin Gebhart, Luca Pezz\`e, Augusto Smerzi
- Abstract summary: We establish conditions under which GMN is demonstrable even if observations are postselected collectively.
Results are derived using the causal structure of the experiment and the no-signalling condition imposed by relativity.
- Score: 0.0
- License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
- Abstract: The generation and verification of genuine multipartite nonlocality (GMN) is
of central interest for both fundamental research and quantum technological
applications, such as quantum privacy. To demonstrate GMN in measurement data,
the statistics are commonly postselected by neglecting undesired data. Until
now, valid postselection strategies have been restricted to local
postselection. A general postselection that is decided after communication
between parties can mimic nonlocality, even though the complete data are local.
Here, we establish conditions under which GMN is demonstrable even if
observations are postselected collectively. Intriguingly, certain postselection
strategies that require communication among several parties still offer a
demonstration of GMN shared between all parties. The results are derived using
the causal structure of the experiment and the no-signalling condition imposed
by relativity. Finally, we apply our results to show that genuine three-partite
nonlocality can be created with independent particle sources.
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