BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Sotaro Sugishita (Nagoya University) DTSTART:20220803T093000Z DTEND:20220803T103000Z DTSTAMP:20260404T111245Z UID:qucos/1 DESCRIPTION:Title: Rindler Bulk Reconstruction and Subregion Duality in AdS/CFT\nby Sotaro Sugishita (Nagoya University) as part of Quantum Cosmos Seminars\n\ n\nAbstract\nIn this talk\, we show that the AdS-Rindler reconstruction is incomplete. CFT operators naively given by the holographic dictionary for the AdS-Rindler reconstruction contain tachyonic modes\, which are incons istent with the causality and unitarity of the CFT. Therefore\, the subreg ion duality and the entanglement wedge reconstruction do not hold. We also find that the tachyonic modes in the AdS-Rindler patch lead to arbitrary high-energy or trans- Planckian modes in the global AdS. It means that the mode expansion of the Rindler patch is sensitive to the UV limit\, i.e.\, quantum gravity. In addition\, the tachyonic modes are related to null ge odesics connecting the past and future horizons. This talk is based on the paper [arXiv:2207.06455] with Seiji Terashima.\n LOCATION:https://stable.researchseminars.org/talk/qucos/1/ END:VEVENT BEGIN:VEVENT SUMMARY:Krishnamohan Parattu (IIT Madras) DTSTART:20220830T093000Z DTEND:20220830T103000Z DTSTAMP:20260404T111245Z UID:qucos/2 DESCRIPTION:Title: Quantum evolution of cosmological perturbations in single and two fie ld inflationary model\nby Krishnamohan Parattu (IIT Madras) as part of Quantum Cosmos Seminars\n\n\nAbstract\nWe believe there was a period of e xponential expansion\, called inflation\, in the evolutionary history of t he universe. Brought on to solve some puzzles in the standard big bang cos mology\, inflation also provides a mechanism of origin for the large scale structure that we see in the universe as the distribution of galaxies and galaxy clusters\, and also the temperature variations in the cosmic micro wave background. According to this picture\, these structures were seeded by quantum fluctuations of the scalar field driving inflation and then st retched out to cosmological scales by the inflationary expansion. Within t his paradigm\, one may ask why these fluctuations appear largely classical . On the other hand\, one may ask if there are any remnant quantum feature s to prove that these fluctuations indeed had a quantum origin. I will dis cuss these issues and present results for some models of current interest in the community for their ability to produce primordial black holes.\n LOCATION:https://stable.researchseminars.org/talk/qucos/2/ END:VEVENT BEGIN:VEVENT SUMMARY:Nilay Kundu (IIT Kanpur) DTSTART:20220913T093000Z DTEND:20220913T110000Z DTSTAMP:20260404T111245Z UID:qucos/3 DESCRIPTION:by Nilay Kundu (IIT Kanpur) as part of Quantum Cosmos Seminars \n\nAbstract: TBA\n LOCATION:https://stable.researchseminars.org/talk/qucos/3/ END:VEVENT BEGIN:VEVENT SUMMARY:Nilay Kundu (IIT Kanpur) DTSTART:20220915T100000Z DTEND:20220915T110000Z DTSTAMP:20260404T111245Z UID:qucos/4 DESCRIPTION:Title: Studying inflationary cosmological correlators using conformal symmet ry in momentum space (part 2)\nby Nilay Kundu (IIT Kanpur) as part of Quantum Cosmos Seminars\n\n\nAbstract\nDuring Inflation the universe was a pproximately described by deSitter (dS) space. The symmetries of a late ti me slice of 4-dimensional dS space are the same as those of a 3-dimensiona l Euclidean Conformal Field Theory (CFT). We will discuss how these symmet ries may impose important constraints on the correlation functions of cosm ological perturbations produced during inflation\, which can directly be o bserved in the CMB. Using these symmetry considerations\, we will understa nd the Ward identities for conformal invariance\, written in momentum spac e\, which imposes restrictions on those correlation functions. We will als o discuss how we can learn about these correlation functions computed in t he alpha vacua of dS space by using CFT techniques in momentum space.\n LOCATION:https://stable.researchseminars.org/talk/qucos/4/ END:VEVENT BEGIN:VEVENT SUMMARY:Ronak Soni (Cambridge University) DTSTART:20220920T140000Z DTEND:20220920T150000Z DTSTAMP:20260404T111245Z UID:qucos/5 DESCRIPTION:Title: Islands with Gravitating Baths: Towards ER = EPR\nby Ronak Soni ( Cambridge University) as part of Quantum Cosmos Seminars\n\n\nAbstract\nWe study the Page curve and the island rule for black holes evaporating into gravitating baths\, with an eye towards establishing a connection with th e ER=EPR proposal. We consider several models of two entangled 2d black ho les in Jackiw-Teitelboim (JT) gravity with negative cosmological constant. The first\, "doubled PSSY\," model is one in which the black holes have e nd-of-the-world (ETW) branes with a flavour degree of freedom. We study hi ghly entangled states of this flavour degree of freedom and find an entang lement-induced Hawking-Page-like transition from a geometry with two disco nnected black holes to one with a pair of black holes connected by a wormh ole\, thus realising the ER = EPR proposal. The second model is a dynamica l one in which the ETW branes do not have internal degrees of freedom but the JT gravity is coupled to a 2d CFT\, and we entangle the black holes by coupling the two CFTs at the AdS boundary and evolving for a long time. W e study the entanglement entropy between the two black holes and find that the story is substantially similar to that with a non-gravitating thermal bath. In the third model\, we couple the two ends of a two-sided eternal black hole and evolve for a long time. Finally\, we discuss the possibilit y of a Hawking-Page-like transition induced by real-time evolution that re alises the ER = EPR proposal in this dynamical setting.\n LOCATION:https://stable.researchseminars.org/talk/qucos/5/ END:VEVENT BEGIN:VEVENT SUMMARY:Yiming Chen (IAS Princeton) DTSTART:20220927T113000Z DTEND:20220927T123000Z DTSTAMP:20260404T111245Z UID:qucos/6 DESCRIPTION:Title: Pulling out the island with modular flow\nby Yiming Chen (IAS Pri nceton) as part of Quantum Cosmos Seminars\n\n\nAbstract\nRecent progress suggests that after the Page time\, the interior of a black hole should be accessible to an outside observer. In this talk\, I will discuss a concre te way to extract information from the interior\, by acting only on the Ha wking radiation. The method makes use of the concept of modular flow\, whi ch has been proposed as a general tool for entanglement wedge reconstructi on in holography. I will show that the methods works nicely in examples wi th JT gravity coupled to baths\, and also comment on the more general situ ations. The main part of the talk will be based on arXiv:1912.02210.\n LOCATION:https://stable.researchseminars.org/talk/qucos/6/ END:VEVENT END:VCALENDAR