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:20260422T225825Z UID:qucos/1 DESCRIPTION:Title: Ri ndler Bulk Reconstruction and Subregion Duality in AdS/CFT\nby Sotaro Sugishita (Nagoya University) as part of Quantum Cosmos Seminars\n\n\nAbst ract\nIn this talk\, we show that the AdS-Rindler reconstruction is incomp lete. CFT operators naively given by the holographic dictionary for the Ad S-Rindler reconstruction contain tachyonic modes\, which are inconsistent with the causality and unitarity of the CFT. Therefore\, the subregion dua lity and the entanglement wedge reconstruction do not hold. We also find t hat the tachyonic modes in the AdS-Rindler patch lead to arbitrary high-en ergy or trans- Planckian modes in the global AdS. It means that the mode e xpansion of the Rindler patch is sensitive to the UV limit\, i.e.\, quantu m gravity. In addition\, the tachyonic modes are related to null geodesics connecting the past and future horizons. This talk is based on the paper [arXiv:2207.06455] with Seiji Terashima.\n LOCATION:https://researchseminars.org/talk/qucos/1/ END:VEVENT BEGIN:VEVENT SUMMARY:Krishnamohan Parattu (IIT Madras) DTSTART:20220830T093000Z DTEND:20220830T103000Z DTSTAMP:20260422T225825Z UID:qucos/2 DESCRIPTION:Title: Qu antum evolution of cosmological perturbations in single and two field infl ationary model\nby Krishnamohan Parattu (IIT Madras) as part of Quantu m Cosmos Seminars\n\n\nAbstract\nWe believe there was a period of exponent ial expansion\, called inflation\, in the evolutionary history of the univ erse. Brought on to solve some puzzles in the standard big bang cosmology\ , inflation also provides a mechanism of origin for the large scale struct ure that we see in the universe as the distribution of galaxies and galaxy clusters\, and also the temperature variations in the cosmic microwave ba ckground. According to this picture\, these structures were seeded by qua ntum fluctuations of the scalar field driving inflation and then stretched out to cosmological scales by the inflationary expansion. Within this par adigm\, one may ask why these fluctuations appear largely classical. On th e other hand\, one may ask if there are any remnant quantum features to pr ove that these fluctuations indeed had a quantum origin. I will discuss th ese issues and present results for some models of current interest in the community for their ability to produce primordial black holes.\n LOCATION:https://researchseminars.org/talk/qucos/2/ END:VEVENT BEGIN:VEVENT SUMMARY:Nilay Kundu (IIT Kanpur) DTSTART:20220913T093000Z DTEND:20220913T110000Z DTSTAMP:20260422T225825Z UID:qucos/3 DESCRIPTION:by Nilay Kundu (IIT Kanpur) as part of Quantum Cosmos Seminars \n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/qucos/3/ END:VEVENT BEGIN:VEVENT SUMMARY:Nilay Kundu (IIT Kanpur) DTSTART:20220915T100000Z DTEND:20220915T110000Z DTSTAMP:20260422T225825Z UID:qucos/4 DESCRIPTION:Title: St udying inflationary cosmological correlators using conformal symmetry in m omentum space (part 2)\nby Nilay Kundu (IIT Kanpur) as part of Quantum Cosmos Seminars\n\n\nAbstract\nDuring Inflation the universe was approxim ately described by deSitter (dS) space. The symmetries of a late time slic e of 4-dimensional dS space are the same as those of a 3-dimensional Eucli dean Conformal Field Theory (CFT). We will discuss how these symmetries ma y impose important constraints on the correlation functions of cosmologica l perturbations produced during inflation\, which can directly be observed in the CMB. Using these symmetry considerations\, we will understand the Ward identities for conformal invariance\, written in momentum space\, whi ch imposes restrictions on those correlation functions. We will also discu ss how we can learn about these correlation functions computed in the alph a vacua of dS space by using CFT techniques in momentum space.\n LOCATION:https://researchseminars.org/talk/qucos/4/ END:VEVENT BEGIN:VEVENT SUMMARY:Ronak Soni (Cambridge University) DTSTART:20220920T140000Z DTEND:20220920T150000Z DTSTAMP:20260422T225825Z UID:qucos/5 DESCRIPTION:Title: Is lands with Gravitating Baths: Towards ER = EPR\nby Ronak Soni (Cambrid ge University) as part of Quantum Cosmos Seminars\n\n\nAbstract\nWe study the Page curve and the island rule for black holes evaporating into gravit ating baths\, with an eye towards establishing a connection with the ER=EP R proposal. We consider several models of two entangled 2d black holes in Jackiw-Teitelboim (JT) gravity with negative cosmological constant. The fi rst\, "doubled PSSY\," model is one in which the black holes have end-of-t he-world (ETW) branes with a flavour degree of freedom. We study highly en tangled states of this flavour degree of freedom and find an entanglement- induced Hawking-Page-like transition from a geometry with two disconnected black holes to one with a pair of black holes connected by a wormhole\, t hus realising the ER = EPR proposal. The second model is a dynamical one i n 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 coupli ng the two CFTs at the AdS boundary and evolving for a long time. We study the entanglement entropy between the two black holes and find that the st ory 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 h ole and evolve for a long time. Finally\, we discuss the possibility of a Hawking-Page-like transition induced by real-time evolution that realises the ER = EPR proposal in this dynamical setting.\n LOCATION:https://researchseminars.org/talk/qucos/5/ END:VEVENT BEGIN:VEVENT SUMMARY:Yiming Chen (IAS Princeton) DTSTART:20220927T113000Z DTEND:20220927T123000Z DTSTAMP:20260422T225825Z UID:qucos/6 DESCRIPTION:Title: Pu lling out the island with modular flow\nby Yiming Chen (IAS Princeton) as part of Quantum Cosmos Seminars\n\n\nAbstract\nRecent progress suggest s that after the Page time\, the interior of a black hole should be access ible to an outside observer. In this talk\, I will discuss a concrete way to extract information from the interior\, by acting only on the Hawking r adiation. The method makes use of the concept of modular flow\, which has been proposed as a general tool for entanglement wedge reconstruction in h olography. I will show that the methods works nicely in examples with JT g ravity coupled to baths\, and also comment on the more general situations. The main part of the talk will be based on arXiv:1912.02210.\n LOCATION:https://researchseminars.org/talk/qucos/6/ END:VEVENT END:VCALENDAR