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:20260423T005716Z UID:HET/1 DESCRIPTION:Title: Quer y complexity and cutoffs in AdS/CFT\nby Bartek Czech (Tsinghua Univers ity) as part of Purdue HET\n\n\nAbstract\nA quantum state is a map from op erators to real numbers that are their expectation values. Evaluating this map always entails using some algorithm\, for example contracting a tenso r network. I propose a novel way of quantifying the complexity of a quantu m state in terms of "query complexity": the number of times an efficient a lgorithm for computing correlation functions in the given state calls on a certain subroutine. I construct such an algorithm for a general "state at a cutoff" in 1+1-dimensional field theory. The algorithm scans cutoff-siz ed intervals for operators whose expectation values will be computed and t he relevant subroutine is a translation in the space of (cutoff-sized) int ervals. Query complexity then boils down to an appropriate notion of dista nce in the space of (cutoff-sized) intervals. A unique distance function i s consistent with the requisite notion of translations\; therefore the que ry complexity of a state at a cutoff is unambiguously defined. In holograp hic theories\, the query complexity evaluates to the integral of the Ricci scalar on a spatial slice enclosed by the bulk cutoff\, which in pure AdS 3 agrees with the volume proposal but otherwise departs from it.\n LOCATION:https://researchseminars.org/talk/HET/1/ END:VEVENT END:VCALENDAR