PIRSA:20110059

Emergent classicality for large channels and states

Ranard, D. (2020). Emergent classicality for large channels and states. Perimeter Institute. https://pirsa.org/20110059

Ranard, Daniel. Emergent classicality for large channels and states. Perimeter Institute, Nov. 18, 2020, https://pirsa.org/20110059 

          @misc{ pirsa_PIRSA:20110059,
            doi = {10.48660/20110059},
            url = {https://pirsa.org/20110059},
            author = {Ranard, Daniel},
            keywords = {Quantum Information},
            language = {en},
            title = {Emergent classicality for large channels and states},
            publisher = {Perimeter Institute},
            year = {2020},
            month = {nov},
            note = {PIRSA:20110059 see, \url{https://pirsa.org}}
          }

Daniel Ranard

California Institute of Technology (Caltech)

Talk number
PIRSA:20110059
Collection
Talk Type
Subject
Abstract

In a quantum measurement process, classical information about the measured system spreads through the environment. In contrast, quantum information about the system becomes inaccessible to local observers. In this talk, I will present a result about quantum channels indicating that an aspect of this phenomenon is completely general. We show that for any evolution of the system and environment, for everywhere in the environment excluding an O(1)-sized region we call the "quantum Markov blanket," any locally accessible information about the system must be approximately classical, i.e. obtainable from some fixed measurement. The result strengthens the earlier result of arXiv:1310.8640 in which the excluded region was allowed to grow with total environment size.  I will also discuss applications to many-body physics.