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6–7 Jun 2025
University of Regina
Canada/Central timezone

Quantum Cryptography, Tensor Networks, and the Python's Lunch

6 Jun 2025, 16:00
15m
191 (Education Bldg)

191

Education Bldg

Contributed Talk Strings and Quantum Gravity

Speaker

Chris Waddell (Perimeter Institute)

Description

In the AdS/CFT correspondence, a subregion of a conformal field theory (CFT) allows for the recovery of a corresponding subregion of the bulk gravity theory known as its entanglement wedge. In some cases, an entanglement wedge contains a locally but not globally minimal surface homologous to the CFT subregion, in which case it is said to contain a python's lunch. It has been proposed that python's lunch geometries should be modelled by tensor networks that feature projective operations where the wedge narrows. This model leads to the python's lunch (PL) conjecture, which asserts that reconstructing information from past the locally minimal surface is computationally difficult.

In this work, we use cryptographic tools related to a primitive known as the Conditional Disclosure of Secrets (CDS) to develop consequences of the projective tensor network model that can be checked directly in AdS/CFT. We argue from the tensor network picture that the mutual information between appropriate CFT subregions is lower bounded linearly by an area difference associated with the geometry of the lunch. Recalling that the mutual information is also computed by bulk extremal surfaces, this gives a verifiable geometrical consequence of the tensor network model. We prove weakened versions of this geometrical statement in asymptotically AdS2+1 spacetimes satisfying the null energy condition, and confirm it in some example geometries, supporting the tensor network model and by proxy the PL conjecture.

Author

Chris Waddell (Perimeter Institute)

Co-authors

Alex May (Perimeter Institute) Michelle Xu (Stanford University) Sabrina Pasterski (Perimeter Institute)

Presentation materials

There are no materials yet.