[quantum-info] Reminder: Q+ Hangout Tuesday Nov 20, Speaker: Rob Spekkens (Perimeter Institute)

[Aharon Brodutch]

Hi all

Rob Spekkens will be presenting  at the next Q+ hangout tomorrow  RAC1 2004
at 9am.

For all those usually interested in the hangout, I encourage you to add it
to your circles on Google plus. There is also an online survey
http://bit.ly/qplussurvey  regarding possible speakers, topics and time.
---

Q+ Hangout Tuesday Nov 20 9am, RAC1 2004, Speaker: Rob Spekkens (Perimeter
Institute)

Title: *Quantum correlations from the perspective of causal discovery
algorithms*

Abstract: If correlation does not imply causation, then what does? The
beginning of a rigorous answer to this question has been provided by
researchers in machine learning, who have developed causal discovery
algorithms. These take as their input facts about correlations among a set
of observed variables and return as their output a causal structure
relating these variables. We show that any attempt to provide a causal
explanation of Bell-inequality-violating correlations must contradict a
core principle of these algorithms, namely, that an observed statistical
independence between variables should not be explained by fine-tuning of
the causal parameters. In particular, we demonstrate the need for such
fine-tuning for most of the causal mechanisms that have been proposed to
underlie Bell correlations, including superluminal causal influences,
superdeterminism (that is, a denial of freedom of choice of settings), and
retrocausal influences which do not introduce causal cycles. This work
suggests a novel perspective on the assumptions underlying Bell's theorem:
the nebulous assumption of "realism" is replaced with the principle that
all correlations ought to be explained causally, and Bell's notion of local
causality is replaced with the assumption of no fine-tuning. Finally, we
discuss the possibility of avoiding the fine-tuning by replacing
conditional probabilities with a noncommutative generalization thereof.

Based on arXiv:1208.4119.
Joint work with Chris Wood.

Cheers
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