BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Bartek Czech (Tsinghua University) DTSTART:20201026T163000Z DTEND:20201026T174500Z DTSTAMP:20260404T132228Z UID:HET/1 DESCRIPTION:Title: Query complexity and cutoffs in AdS/CFT\nby Bartek Czech (Tsinghua University) as part of Purdue HET\n\n\nAbstract\nA quantum state is a map from operators to real numbers that are their expectation values. Evaluati ng this map always entails using some algorithm\, for example contracting a tensor network. I propose a novel way of quantifying the complexity of a quantum state in terms of "query complexity": the number of times an effi cient algorithm for computing correlation functions in the given state cal ls on a certain subroutine. I construct such an algorithm for a general "s tate at a cutoff" in 1+1-dimensional field theory. The algorithm scans cut off-sized intervals for operators whose expectation values will be compute d and the relevant subroutine is a translation in the space of (cutoff-siz ed) intervals. Query complexity then boils down to an appropriate notion o f distance in the space of (cutoff-sized) intervals. A unique distance fun ction is consistent with the requisite notion of translations\; therefore the query complexity of a state at a cutoff is unambiguously defined. In h olographic theories\, the query complexity evaluates to the integral of th e Ricci scalar on a spatial slice enclosed by the bulk cutoff\, which in p ure AdS3 agrees with the volume proposal but otherwise departs from it.\n LOCATION:https://stable.researchseminars.org/talk/HET/1/ END:VEVENT END:VCALENDAR