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BEGIN:VEVENT
SUMMARY:Sumit R. Das (University of Kentucky)
DTSTART:20200514T143000Z
DTEND:20200514T153000Z
DTSTAMP:20260404T111100Z
UID:IPMHolographySeminar/1
DESCRIPTION:Title: Bulk entanglement and holography\nby Sumit R. Das
(University of Kentucky) as part of IPM Holography Virtual Seminars\n\n\nA
bstract\nWe argue that the entanglement between regions of the target spac
e of a large $N$ field theory with a smooth holographic dual provides a p
recise meaning to the entanglement of a region in the bulk. We conjecture
that the leading answer for this quantity is $A/4G$\, where $A$ is the are
a of the entangling surface and $G$ is Newton's constant. For specially ch
osen regions in $D_p$ brane backgrounds\, we provide a precise map to the
target space of the dual theory. Our conjecture then leads to the conclusi
on that this target space entanglement entropy should scale like $O(N^2)$
which is quite plausible in a system with $O(N^2)$ degrees of freedom. Rec
ent numerical advances in studying the $D_0$ brane system hold out hope th
at this proposal can be tested in a precise way in the future.\n(Based on
Sumit R. Das\, Anurag Kaushal\, Gautam Mandal and Sandip Trivedi\, arxiv:
2004.00613)\n\nJoin Zoom Meeting\nhttps://us02web.zoom.us/j/89697900502?pw
d=WWZaaW4xcWtHd0ExdkNzTHRmR3crZz09\n\nMeeting ID: 896 9790 0502\nPassword:
761472\n
LOCATION:https://stable.researchseminars.org/talk/IPMHolographySeminar/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Edgar Shaghoulian (Cornell University)
DTSTART:20200521T123000Z
DTEND:20200521T133000Z
DTSTAMP:20260404T111100Z
UID:IPMHolographySeminar/2
DESCRIPTION:Title: Replica wormholes and the black hole information parad
ox\nby Edgar Shaghoulian (Cornell University) as part of IPM Holograph
y Virtual Seminars\n\n\nAbstract\nWe will analyze the information paradox
in two-dimensional models of gravity. In this setting\, we will show that
new saddles in the gravitational path integral imply a unitary Page curve
for the entropy of Hawking radiation. These saddles arise in the replica m
ethod as wormholes connecting different copies of the black hole. We will
focus on these saddles in anti-de Sitter spacetime\, but if time permits w
e will also discuss flat and de Sitter spacetimes.\n
LOCATION:https://stable.researchseminars.org/talk/IPMHolographySeminar/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Juan F. Pedraza (University College London & Brandeis University)
DTSTART:20200528T093000Z
DTEND:20200528T103000Z
DTSTAMP:20260404T111100Z
UID:IPMHolographySeminar/3
DESCRIPTION:Title: Local quenches\, bulk entanglement entropy and a unita
ry Page curve\nby Juan F. Pedraza (University College London & Brandei
s University) as part of IPM Holography Virtual Seminars\n\n\nAbstract\nQu
antum corrections to the entanglement entropy of matter fields interacting
with dynamical gravity have proven to be very important in the study of t
he black hole information problem. We consider a one-particle excited stat
e of a massive scalar field infalling in a pure $AdS_3$ geometry and compu
te these corrections for bulk subregions anchored on the AdS boundary. In
the dual $CFT_2$\, the state is given by the insertion of a local primary
operator and its evolution thereafter. We calculate the area and bulk enta
nglement entropy corrections at order $\\mathcal{O}(N^0)$\, both in AdS an
d its CFT dual. The two calculations match\, thus providing a non-trivial
check of the FLM formula in a dynamical setting. Further\, we observe that
the bulk entanglement entropy follows a Page curve. We explain the precis
e sense in which our setup can be interpreted as a simple model of black h
ole evaporation and comment on the implications for the information proble
m.\n\nMeeting ID: 852 4153 8685 Password: 343561\n
LOCATION:https://stable.researchseminars.org/talk/IPMHolographySeminar/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:James Sully (University of British Columbia)
DTSTART:20200604T043000Z
DTEND:20200604T053000Z
DTSTAMP:20260404T111100Z
UID:IPMHolographySeminar/4
DESCRIPTION:Title: Eigenstate Thermalization and Disorder Averaging in Gr
avity\nby James Sully (University of British Columbia) as part of IPM
Holography Virtual Seminars\n\n\nAbstract\nIt has long been believed that
progress in understanding the black hole information paradox would require
coming to terms with microscopic details of quantum gravity---something b
eyond the reach of semiclassical effective field theory. In that light\, o
ne of the most surprising discoveries of the last year has been that signa
ture features of the unitary evaporation of black holes can already be see
n within effective field theory\, albeit with the inclusion of 'euclidean
wormholes'. However\, these novel contributions are best understood when t
he gravitational theory is not a single microscopic theory\, but an averag
e over many different theories. To save unitarity must we then simultaneou
sly throw it away? I will explain how the same story can be recovered with
in a single microscopic theory by thinking carefully about the right effec
tive theory for finite-lifetime observers.\n\nMeeting ID: 895 9741 7637\nP
assword: 337380\n
LOCATION:https://stable.researchseminars.org/talk/IPMHolographySeminar/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:S. Prem Kumar (Swansea University)
DTSTART:20200611T093000Z
DTEND:20200611T103000Z
DTSTAMP:20260404T111100Z
UID:IPMHolographySeminar/5
DESCRIPTION:Title: Islands and Page Curves for Evaporating Black Holes\nby S. Prem Kumar (Swansea University) as part of IPM Holography Virtual
Seminars\n\n\nAbstract\nI will describe the effect of a shockwave on the
entanglement structure of a black hole within JT gravity. Focusing attenti
on on an analytically tractable semiclassical description\, we discuss how
the Page time and associated time-dependent quantum extremal surface are
affected by the shockwave and subsequent relaxation of the black hole via
evaporation.\n\nMeeting ID: 898 9692 9849\nPassword: 847891\n
LOCATION:https://stable.researchseminars.org/talk/IPMHolographySeminar/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nima Afkhami-Jeddi (University of Chicago)
DTSTART:20200702T040000Z
DTEND:20200702T050000Z
DTSTAMP:20260404T111100Z
UID:IPMHolographySeminar/6
DESCRIPTION:Title: 3d gravity from averaging 2d CFTs\nby Nima Afkhami
-Jeddi (University of Chicago) as part of IPM Holography Virtual Seminars\
n\n\nAbstract\nWe study the torus partition functions of free compatic bos
onic CFTs in two dimensions. Integrating over Narain moduli defines an ens
emble-averaged free CFT. We calculate the averaged partition function and
show that it can be reinterpreted as a sum over topologies in three dimens
ions. This result leads us to conjecture that an averaged free CFT in two
dimensions is holographically dual to an exotic theory of three-dimensiona
l gravity.\n\nMeeting ID: 812 5763 7854\nPassword: 611391\n
LOCATION:https://stable.researchseminars.org/talk/IPMHolographySeminar/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jorrit Kruthoff (Stanford University)
DTSTART:20200723T050000Z
DTEND:20200723T060000Z
DTSTAMP:20260404T111100Z
UID:IPMHolographySeminar/7
DESCRIPTION:Title: On the flow of states under $T\\bar{T}$\nby Jorrit
Kruthoff (Stanford University) as part of IPM Holography Virtual Seminars
\n\n\nAbstract\nWe study the $T\\bar{T}$ deformation of two dimensional qu
antum field theories from a Hamiltonian point of view\, focusing on aspect
s of the theory in Lorentzian signature. Our starting point is a simple re
writing of the spatial integral of the $T\\bar{T}$ operator\, which direct
ly implies the deformed energy spectrum of the theory. Using this rewritin
g\, we then derive flow equations for various quantities in the deformed t
heory\, such as energy eigenstates\, operators\, and correlation functions
. On the plane\, we find that the deformation merely has the effect of imp
lementing successive canonical/Bogoliubov transformations along the flow.
This leads us to define a class of non-local\, “dressed” operators (in
cluding a dressed stress tensor) which satisfy the same commutation relati
ons as in the undeformed theory. This further implies that on the plane\,
the deformed theory retains its symmetry algebra\, including conformal sym
metry\, if the original theory is a CFT. On the cylinder the $T\\bar{T}$ d
eformation is much more non-trivial\, but even so\, correlation functions
of certain dressed operators are integral transforms of the original ones.
Finally\, we propose a tensor network interpretation of our results in th
e context of AdS/CFT.\n\nMeeting ID: 845 5363 7892\nPassword: 713874\n
LOCATION:https://stable.researchseminars.org/talk/IPMHolographySeminar/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Monica Kang (Caltech)
DTSTART:20200903T050000Z
DTEND:20200903T060000Z
DTSTAMP:20260404T111100Z
UID:IPMHolographySeminar/8
DESCRIPTION:Title: Holographic baby universes: an observable story\nb
y Monica Kang (Caltech) as part of IPM Holography Virtual Seminars\n\n\nAb
stract\nI will introduce a formalism based on GNS construction for studyin
g baby universes. By shifting the primordial role to the algebra of observ
ables rather than the Hilbert spaces\, I will introduce baby universe oper
ations\, build baby universe algebra\, and construct the baby universe Hil
bert spaces. I will further explain how this approach will give an underst
anding of the miraculous cancellation as a natural result from the charact
er theory. I will illustrate by giving two different physical settings as
examples.\n\nMeeting ID: 883 8776 2345\nPassword: 840732\n
LOCATION:https://stable.researchseminars.org/talk/IPMHolographySeminar/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:David Kolchmeyer (Harvard)
DTSTART:20210520T123000Z
DTEND:20210520T133000Z
DTSTAMP:20260404T111100Z
UID:IPMHolographySeminar/9
DESCRIPTION:Title: Dynamical End-of-the-world Branes in Jackiw-Teitelboim
Gravity\nby David Kolchmeyer (Harvard) as part of IPM Holography Virt
ual Seminars\n\n\nAbstract\nJackiw-Teitelboim gravity with end-of-the-worl
d (EoW) branes has been used to study the black hole information problem.
In this talk\, I consider dynamical EoW branes by summing over loops of br
anes in the Euclidean path integral. The UV divergences that arise are tre
ated in the context of effective field theory. The EoW branes make a contr
ibution to the black hole entropy that is consistent with a state-counting
interpretation of the entropy. I will also discuss how the effective fiel
d theory logic is mirrored in the dual matrix model.\n
LOCATION:https://stable.researchseminars.org/talk/IPMHolographySeminar/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Baurzhan Mukhametzhanov (IAS)
DTSTART:20210706T123000Z
DTEND:20210706T133000Z
DTSTAMP:20260404T111100Z
UID:IPMHolographySeminar/10
DESCRIPTION:Title: Half-wormholes and factorization problem\nby Baur
zhan Mukhametzhanov (IAS) as part of IPM Holography Virtual Seminars\n\n\n
Abstract\nI will discuss the factorization problem in an SYK model with on
e time point. Working in a collective field description\, one can derive a
n identity: the square of the partition function with fixed couplings is w
ell approximated by a “wormhole” saddle plus a “half-wormhole” sad
dle. It explains factorization of decoupled systems. I will develop a pert
urbative expansion around the half-wormhole saddle. This expansion truncat
es at a finite order and gives the exact answer. The last term in the pert
urbative expansion turns out to coincide with the wormhole contribution. I
n this sense the wormhole saddle in this model does not need to be added s
eparately\, but instead can be viewed as a large fluctuation around the ha
lf-wormhole.\n
LOCATION:https://stable.researchseminars.org/talk/IPMHolographySeminar/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lampros Lamprou (UBC)
DTSTART:20210907T053000Z
DTEND:20210907T063000Z
DTSTAMP:20260404T111100Z
UID:IPMHolographySeminar/11
DESCRIPTION:Title: Falling inside holographic black holes\nby Lampro
s Lamprou (UBC) as part of IPM Holography Virtual Seminars\n\n\nAbstract\n
I will present a bulk reconstruction technique in AdS/CFT suitable for add
ressing a facet of the black hole information problem: how to unambiguousl
y predict the results of measurements accessible to an infalling observer
in the black hole interior.\n
LOCATION:https://stable.researchseminars.org/talk/IPMHolographySeminar/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mark Mezei (SCGP\, Stony Brook)
DTSTART:20210914T123000Z
DTEND:20210914T133000Z
DTSTAMP:20260404T111100Z
UID:IPMHolographySeminar/12
DESCRIPTION:Title: The volume of the black hole interior at late times\nby Mark Mezei (SCGP\, Stony Brook) as part of IPM Holography Virtual S
eminars\n\n\nAbstract\nUnderstanding the fate of semi-classical black hole
solutions at very late times is one of the most important open questions
in quantum gravity. In this talk\, we provide a path integral definition o
f the volume of the black hole interior and study it at arbitrarily late t
imes for black holes in various models of two-dimensional gravity. Because
of a novel universal cancellation between the contributions of the semi-c
lassical black hole spectrum and some of its non-perturbative corrections\
, we find that\, after a linear growth at early times\, the length of the
interior saturates at a time\, and towards a value\, that is exponentially
large in the entropy of the black hole. This provides a non-perturbative
confirmation of the complexity equals volume proposal since complexity is
also expected to plateau at the same value and at the same time.\n
LOCATION:https://stable.researchseminars.org/talk/IPMHolographySeminar/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mikhail Khramtsov (Vrije Universiteit Brussel)
DTSTART:20210928T133000Z
DTEND:20210928T143000Z
DTSTAMP:20260404T111100Z
UID:IPMHolographySeminar/13
DESCRIPTION:Title: Submerging islands through thermalization\nby Mik
hail Khramtsov (Vrije Universiteit Brussel) as part of IPM Holography Virt
ual Seminars\n\n\nAbstract\nWe illustrate scenarios in which Hawking radia
tion collected in finite regions of a reservoir provides temporary access
to the interior of eternal black holes through transient entanglement "isl
ands". Whether these islands appear and the amount of time for which they
dominate - sometimes giving way to a thermalization transition - is contro
lled by the amount of radiation we probe. In the first scenario\, two rese
rvoirs are coupled to an eternal black hole. The second scenario involves
two holographic quantum gravitating systems at different temperatures inte
racting through a Rindler-like reservoir\, which acts as a heat engine mai
ntaining thermal equilibrium. This situation describes two eternal black h
oles radiating into each other through a shared reservoir. We will also di
scuss the analogous effect in the evaporating AdS2 black hole.\n
LOCATION:https://stable.researchseminars.org/talk/IPMHolographySeminar/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Pranjal Nayak (Geneva University)
DTSTART:20211019T133000Z
DTEND:20211019T143000Z
DTSTAMP:20260404T111100Z
UID:IPMHolographySeminar/14
DESCRIPTION:Title: Wormholes in Quantum Ergodicity\nby Pranjal Nayak
(Geneva University) as part of IPM Holography Virtual Seminars\n\n\nAbstr
act\nFor a generic quantum many-body system\, the quantum ergodic regime i
s defined as the limit in which the spectrum of the system resembles that
of a random matrix theory (RMT) in the corresponding symmetry class. In th
is talk I will discuss the time dependence of correlation functions of ope
rators in the SYK model\, in the ergodic limit as well as their approach t
o the ergodic limit which is controlled by non-universal massive modes. An
effective field theory (EFT) corresponding to the causal symmetry and its
breaking describes the ergodic phase. I will discuss the topological expa
nsion of the resulting Goldstone-mode theory where the leading non-trivial
topologies give rise to the universal ramp seen in correlation functions.
Furthermore we analytically capture the plateau behaviour by taking into
account the contribution of a second saddle point. These results explicitl
y establish the validity of the EFT description in the SYK-class of models
\, starting from their microscopic description. I will discuss the tower o
f massive modes above the Goldstone sector that govern how the ergodic EFT
phase is approached and derive the relevant Thouless time scales.\n\nIn t
he second part of the talk\, I will discuss the connections between the Ei
genstate thermalisation hypothesis (ETH) and the Euclidean wormholes. Moti
vated by this connections I will discuss our proposal for ETH for charged
operators in quantum theories with global symmetries.\n
LOCATION:https://stable.researchseminars.org/talk/IPMHolographySeminar/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jie-qiang Wu (UCSB)
DTSTART:20211026T133000Z
DTEND:20211026T143000Z
DTSTAMP:20260404T111100Z
UID:IPMHolographySeminar/15
DESCRIPTION:Title: Algebra of diffeomorphism invariant observables in Ja
ckiw-Teitelboim gravity\nby Jie-qiang Wu (UCSB) as part of IPM Hologra
phy Virtual Seminars\n\n\nAbstract\nDiffeomorphism symmetry is an intrinsi
c difficulty in gravitational theory\, which appears in\nalmost all of the
questions in gravity. As is well known\, the diffeomorphism symmetries in
gravity should\nbe interpreted as gauge symmetries\, so only diffeomorphi
sm invariant operators are physically\ninteresting. However\, because of t
he non-linear effect of gravitational theory\, the results for\ndiffeomorp
hism invariant operators are very limited.\nIn this work\, we focus on the
Jackiw-Teitelboim gravity in classical limit\, and use Peierls bracket (w
hich is\na linear response like computation of observables’ bracket) to
compute the algebra of a large class of\ndiffeomorphism invariant observab
les. With this algebra\, we can reproduce some recent results in\nJackiw-T
eitelboim gravity including: traversable wormhole\, scrambling effect\, an
d SL(2) charges. We can\nalso use it to clarify the question of when the c
reation of an excitation deep in the bulk increases or\ndecreases the boun
dary energy\, which is of crucial importance for the “typical state” v
ersion of the\nfirewall paradox.\nIn the talk\, I will first give a brief
introduction of Peierls bracket\, and then use the Peierls bracket to\nstu
dy the brackets between diffeomorphism invariant observables in Jackiw-Tei
telboim gravity. I will\nthen give two applications of this algebra: repro
ducing the scrambling effect\, and studying the energy\nchange after creat
ing an excitation in the bulk.\n
LOCATION:https://stable.researchseminars.org/talk/IPMHolographySeminar/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Krishan Saraswat (Perimeter Institute)
DTSTART:20211123T143000Z
DTEND:20211123T153000Z
DTSTAMP:20260404T111100Z
UID:IPMHolographySeminar/16
DESCRIPTION:Title: Spacing Statistics of Energy Spectra: Random Matrices
\, Black Hole Thermalization\, and Echoes\nby Krishan Saraswat (Perime
ter Institute) as part of IPM Holography Virtual Seminars\n\n\nAbstract\nR
ecent advances in AdS/CFT suggest that the near-horizon dynamics of black
holes can be described by unitary random matrix systems. Motivated by thes
e developments\, I will discuss how the energy spectrum of a system with a
generic random Hamiltonian matrix affects its early and late time thermal
ization behaviour using the spectral form factor (which captures the time-
dependence of two-point correlation functions) and connect it to the discu
ssion of gravitational wave echoes. In particular\, I will demonstrate tha
t it is possible for quantum chaotic systems to exhibit echoes if the ener
gy spectrum contains many clusters of eigenvalues which are regularly spac
ed from each other. I will discuss the example of a randomly coupled oscil
lator system and show that at weak coupling the form factor exhibits echoe
s. I will speculate on the holographic interpretation of a system of weakl
y coupled oscillators\, and give a heuristic picture of how they might des
cribe the thermalization behaviour of a black hole geometry with a membran
e that cuts off the geometry at the stretched horizon. I will also discuss
the role that symmetries play in quantum chaotic systems that exhibit ech
oes.\n
LOCATION:https://stable.researchseminars.org/talk/IPMHolographySeminar/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jonah Kudler-Flam (University of Chicago)
DTSTART:20211130T133000Z
DTEND:20211130T143000Z
DTSTAMP:20260404T111100Z
UID:IPMHolographySeminar/17
DESCRIPTION:Title: Distinguishability in Random States\, Eigenstates\, a
nd Gravity\nby Jonah Kudler-Flam (University of Chicago) as part of IP
M Holography Virtual Seminars\n\n\nAbstract\nRecently\, there has been sig
nificant progress in solving the black hole information problem from expli
cit calculations of the entropy of Hawking radiation\, confirming consiste
ncy of gravity with unitarity. One aspect of the information problem left
unresolved by entropy calculations is the distinguishability of different
black hole microstates: why do different microstates appear to lead to the
same final (thermal) state? I will address this problem by studying the d
istinguishability of radiation coming from different black holes. In paral
lel\, I will present a derivation of the subsystem eigenstate thermalizati
on hypothesis for a class of chaotic many-body systems as well as generali
zations to tensor network states.\n
LOCATION:https://stable.researchseminars.org/talk/IPMHolographySeminar/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Aasmund Folkestad (MIT)
DTSTART:20220118T133000Z
DTEND:20220118T143000Z
DTSTAMP:20260404T111100Z
UID:IPMHolographySeminar/18
DESCRIPTION:Title: General Bounds on Holographic Complexity\nby Aasm
und Folkestad (MIT) as part of IPM Holography Virtual Seminars\n\n\nAbstra
ct\nIn this talk\, we present novel rigorous bounds on maximal volume slic
es in asymptotically AdS spacetimes. Under the Complexity=Volume conjectur
e\, these results imply that the CFT vacuum is the simplest state\, provid
ed we assume the weak energy condition and no compact bulk dimensions. Ne
xt\, we show that compact dimensions or tachyonic scalar fields can violat
e our result\, giving rise to distinct effects that should be reproduced b
y any proposed dual to maximal volumes. Finally\, we present a speed limi
t on the growth of volumes in terms of spacetime mass\, which under the CV
conjecture constitutes a holographic proof of Lloyd's bound for a class o
f spacetimes.\n
LOCATION:https://stable.researchseminars.org/talk/IPMHolographySeminar/18/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Batoul Banihashemi (University of Maryland)
DTSTART:20220517T123000Z
DTEND:20220517T133000Z
DTSTAMP:20260404T111100Z
UID:IPMHolographySeminar/19
DESCRIPTION:Title: Thermodynamic ensembles with cosmological horizons\nby Batoul Banihashemi (University of Maryland) as part of IPM Holograph
y Virtual Seminars\n\n\nAbstract\nThe entropy of a de Sitter horizon was d
erived long ago by Gibbons and Hawking via a gravitational partition funct
ion. Since there is no boundary at which to define the temperature or ener
gy of the ensemble\, the statistical foundation of their approach has rema
ined obscure. To place the statistical ensemble on a firm footing we intro
duce an artificial “York boundary”\, with either canonical or microcan
onical boundary conditions\, as has been done previously for black hole en
sembles. The partition function and the density of states are expressed as
integrals over paths in the constrained\, spherically reduced phase space
of pure 3+1 dimensional gravity with a positive cosmological constant. Th
e canonical ensemble includes a patch of spacetime without horizon\, as we
ll as configurations containing a black hole or a cosmological horizon. In
this talk I briefly discuss issues related to the domain and contour of i
ntegration in the path integral\, and justify the adopted choices for thos
e as far as possible. I also explain thermodynamic phases and (in)stabilit
y\, and discuss an evolving reservoir model that can stabilize the cosmolo
gical horizon in the canonical ensemble. Finally\, I explain how the Gibbo
ns-Hawking partition function on the 4-sphere can be derived as a limit of
well-defined thermodynamic ensembles.\n
LOCATION:https://stable.researchseminars.org/talk/IPMHolographySeminar/19/
END:VEVENT
END:VCALENDAR