Next Q+ Hangout is on November 8th!

As usual, if you are watching with a group and want to reserve a seat in the hangout then leave a comment here:

https://plus.google.com/+QplusHangouts/posts/EoCJW8wGrDi

We also encourage individuals interested in active participation---which typically involves asking questions after the talk---to join the hangout. Otherwise you can watch on the livestream. Details follow.

Speaker: Miguel Navascues

Title: Entanglement and Nonlocality of 1D Macroscopic Systems

Abstract: We consider the problem of certifying entanglement and nonlocality in one-dimensional macroscopic systems when just averaged near-neighbor correlators are available. We map this question to the characterization of the set of all quantum states (distributions) which admit a separable (classical) Translation-Invariant (TI) extension to infinitely many sites. We advance the first problem by constructing a family of witnesses which can detect entanglement in infinite TI states from the nearest-neighbor reduced density matrix. Along the way, we identify a set of separable two-qubit states which only admit entangled TI extensions. For nonlocality detection, we show that the set of classical TI boxes forms a polytope and devise a general procedure to generate all Bell inequalities which characterize it. Through a Matrix Product State-based method, we show how some of them can be violated by distant parties conducting identical measurements on an infinite TI quantum state.

Livestream link: https://www.youtube.com/watch?v=awvdeBtcubY

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