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BEGIN:VEVENT
SUMMARY:Sumit R. Das (University of Kentucky)
DTSTART:20200514T143000Z
DTEND:20200514T153000Z
DTSTAMP:20260422T212934Z
UID:IPMHolographySeminar/1
DESCRIPTION:Title: Bulk entanglement and holography\nby Sumit R. Das (Univer
sity of Kentucky) as part of IPM Holography Virtual Seminars\n\n\nAbstract
\nWe argue that the entanglement between regions of the target space of a
large $N$ field theory with a smooth holographic dual provides a precise
meaning to the entanglement of a region in the bulk. We conjecture that th
e leading answer for this quantity is $A/4G$\, where $A$ is the area of th
e entangling surface and $G$ is Newton's constant. For specially chosen re
gions in $D_p$ brane backgrounds\, we provide a precise map to the target
space of the dual theory. Our conjecture then leads to the conclusion that
this target space entanglement entropy should scale like $O(N^2)$ which i
s quite plausible in a system with $O(N^2)$ degrees of freedom. Recent num
erical advances in studying the $D_0$ brane system hold out hope that 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: 2004.00
613)\n\nJoin Zoom Meeting\nhttps://us02web.zoom.us/j/89697900502?pwd=WWZaa
W4xcWtHd0ExdkNzTHRmR3crZz09\n\nMeeting ID: 896 9790 0502\nPassword: 76147
2\n
LOCATION:https://researchseminars.org/talk/IPMHolographySeminar/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Edgar Shaghoulian (Cornell University)
DTSTART:20200521T123000Z
DTEND:20200521T133000Z
DTSTAMP:20260422T212934Z
UID:IPMHolographySeminar/2
DESCRIPTION:Title: Replica wormholes and the black hole information paradox\
nby Edgar Shaghoulian (Cornell University) as part of IPM Holography Virtu
al Seminars\n\n\nAbstract\nWe will analyze the information paradox in two-
dimensional models of gravity. In this setting\, we will show that new sad
dles in the gravitational path integral imply a unitary Page curve for the
entropy of Hawking radiation. These saddles arise in the replica method a
s wormholes connecting different copies of the black hole. We will focus o
n these saddles in anti-de Sitter spacetime\, but if time permits we will
also discuss flat and de Sitter spacetimes.\n
LOCATION:https://researchseminars.org/talk/IPMHolographySeminar/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Juan F. Pedraza (University College London & Brandeis University)
DTSTART:20200528T093000Z
DTEND:20200528T103000Z
DTSTAMP:20260422T212934Z
UID:IPMHolographySeminar/3
DESCRIPTION:Title: Local quenches\, bulk entanglement entropy and a unitary Page
curve\nby Juan F. Pedraza (University College London & Brandeis Unive
rsity) as part of IPM Holography Virtual Seminars\n\n\nAbstract\nQuantum c
orrections to the entanglement entropy of matter fields interacting with d
ynamical gravity have proven to be very important in the study of the blac
k hole information problem. We consider a one-particle excited state of a
massive scalar field infalling in a pure $AdS_3$ geometry and compute thes
e corrections for bulk subregions anchored on the AdS boundary. In the dua
l $CFT_2$\, the state is given by the insertion of a local primary operato
r and its evolution thereafter. We calculate the area and bulk entanglemen
t entropy corrections at order $\\mathcal{O}(N^0)$\, both in AdS and its C
FT dual. The two calculations match\, thus providing a non-trivial check o
f the FLM formula in a dynamical setting. Further\, we observe that the bu
lk entanglement entropy follows a Page curve. We explain the precise sense
in which our setup can be interpreted as a simple model of black hole eva
poration and comment on the implications for the information problem.\n\nM
eeting ID: 852 4153 8685 Password: 343561\n
LOCATION:https://researchseminars.org/talk/IPMHolographySeminar/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:James Sully (University of British Columbia)
DTSTART:20200604T043000Z
DTEND:20200604T053000Z
DTSTAMP:20260422T212934Z
UID:IPMHolographySeminar/4
DESCRIPTION:Title: Eigenstate Thermalization and Disorder Averaging in Gravity\nby James Sully (University of British Columbia) as part of IPM Hologra
phy Virtual Seminars\n\n\nAbstract\nIt has long been believed that progres
s in understanding the black hole information paradox would require coming
to terms with microscopic details of quantum gravity---something beyond t
he reach of semiclassical effective field theory. In that light\, one of t
he most surprising discoveries of the last year has been that signature fe
atures of the unitary evaporation of black holes can already be seen withi
n effective field theory\, albeit with the inclusion of 'euclidean wormhol
es'. However\, these novel contributions are best understood when the grav
itational theory is not a single microscopic theory\, but an average over
many different theories. To save unitarity must we then simultaneously thr
ow it away? I will explain how the same story can be recovered within a si
ngle microscopic theory by thinking carefully about the right effective th
eory for finite-lifetime observers.\n\nMeeting ID: 895 9741 7637\nPassword
: 337380\n
LOCATION:https://researchseminars.org/talk/IPMHolographySeminar/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:S. Prem Kumar (Swansea University)
DTSTART:20200611T093000Z
DTEND:20200611T103000Z
DTSTAMP:20260422T212934Z
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 Semina
rs\n\n\nAbstract\nI will describe the effect of a shockwave on the entangl
ement structure of a black hole within JT gravity. Focusing attention on a
n analytically tractable semiclassical description\, we discuss how the Pa
ge time and associated time-dependent quantum extremal surface are affecte
d by the shockwave and subsequent relaxation of the black hole via evapora
tion.\n\nMeeting ID: 898 9692 9849\nPassword: 847891\n
LOCATION:https://researchseminars.org/talk/IPMHolographySeminar/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nima Afkhami-Jeddi (University of Chicago)
DTSTART:20200702T040000Z
DTEND:20200702T050000Z
DTSTAMP:20260422T212934Z
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\nAb
stract\nWe study the torus partition functions of free compatic bosonic CF
Ts in two dimensions. Integrating over Narain moduli defines an ensemble-a
veraged free CFT. We calculate the averaged partition function and show th
at it can be reinterpreted as a sum over topologies in three dimensions. T
his result leads us to conjecture that an averaged free CFT in two dimensi
ons is holographically dual to an exotic theory of three-dimensional gravi
ty.\n\nMeeting ID: 812 5763 7854\nPassword: 611391\n
LOCATION:https://researchseminars.org/talk/IPMHolographySeminar/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jorrit Kruthoff (Stanford University)
DTSTART:20200723T050000Z
DTEND:20200723T060000Z
DTSTAMP:20260422T212934Z
UID:IPMHolographySeminar/7
DESCRIPTION:Title: On the flow of states under $T\\bar{T}$\nby Jorrit Krutho
ff (Stanford University) as part of IPM Holography Virtual Seminars\n\n\nA
bstract\nWe study the $T\\bar{T}$ deformation of two dimensional quantum f
ield theories from a Hamiltonian point of view\, focusing on aspects of th
e theory in Lorentzian signature. Our starting point is a simple rewriting
of the spatial integral of the $T\\bar{T}$ operator\, which directly impl
ies the deformed energy spectrum of the theory. Using this rewriting\, we
then derive flow equations for various quantities in the deformed theory\,
such as energy eigenstates\, operators\, and correlation functions. On th
e plane\, we find that the deformation merely has the effect of implementi
ng successive canonical/Bogoliubov transformations along the flow. This le
ads us to define a class of non-local\, “dressed” operators (including
a dressed stress tensor) which satisfy the same commutation relations as
in the undeformed theory. This further implies that on the plane\, the def
ormed theory retains its symmetry algebra\, including conformal symmetry\,
if the original theory is a CFT. On the cylinder the $T\\bar{T}$ deformat
ion is much more non-trivial\, but even so\, correlation functions of cert
ain dressed operators are integral transforms of the original ones. Finall
y\, we propose a tensor network interpretation of our results in the conte
xt of AdS/CFT.\n\nMeeting ID: 845 5363 7892\nPassword: 713874\n
LOCATION:https://researchseminars.org/talk/IPMHolographySeminar/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Monica Kang (Caltech)
DTSTART:20200903T050000Z
DTEND:20200903T060000Z
DTSTAMP:20260422T212934Z
UID:IPMHolographySeminar/8
DESCRIPTION:Title: Holographic baby universes: an observable story\nby Monic
a Kang (Caltech) as part of IPM Holography Virtual Seminars\n\n\nAbstract\
nI will introduce a formalism based on GNS construction for studying baby
universes. By shifting the primordial role to the algebra of observables r
ather than the Hilbert spaces\, I will introduce baby universe operations\
, build baby universe algebra\, and construct the baby universe Hilbert sp
aces. I will further explain how this approach will give an understanding
of the miraculous cancellation as a natural result from the character theo
ry. I will illustrate by giving two different physical settings as example
s.\n\nMeeting ID: 883 8776 2345\nPassword: 840732\n
LOCATION:https://researchseminars.org/talk/IPMHolographySeminar/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:David Kolchmeyer (Harvard)
DTSTART:20210520T123000Z
DTEND:20210520T133000Z
DTSTAMP:20260422T212934Z
UID:IPMHolographySeminar/9
DESCRIPTION:Title: Dynamical End-of-the-world Branes in Jackiw-Teitelboim Gravit
y\nby David Kolchmeyer (Harvard) as part of IPM Holography Virtual Sem
inars\n\n\nAbstract\nJackiw-Teitelboim gravity with end-of-the-world (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 branes in
the Euclidean path integral. The UV divergences that arise are treated in
the context of effective field theory. The EoW branes make a contribution
to the black hole entropy that is consistent with a state-counting interp
retation of the entropy. I will also discuss how the effective field theor
y logic is mirrored in the dual matrix model.\n
LOCATION:https://researchseminars.org/talk/IPMHolographySeminar/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Baurzhan Mukhametzhanov (IAS)
DTSTART:20210706T123000Z
DTEND:20210706T133000Z
DTSTAMP:20260422T212934Z
UID:IPMHolographySeminar/10
DESCRIPTION:Title: Half-wormholes and factorization problem\nby Baurzhan Mu
khametzhanov (IAS) as part of IPM Holography Virtual Seminars\n\n\nAbstrac
t\nI will discuss the factorization problem in an SYK model with one time
point. Working in a collective field description\, one can derive an ident
ity: the square of the partition function with fixed couplings is well app
roximated by a “wormhole” saddle plus a “half-wormhole” saddle. It
explains factorization of decoupled systems. I will develop a perturbativ
e expansion around the half-wormhole saddle. This expansion truncates at a
finite order and gives the exact answer. The last term in the perturbativ
e expansion turns out to coincide with the wormhole contribution. In this
sense the wormhole saddle in this model does not need to be added separate
ly\, but instead can be viewed as a large fluctuation around the half-worm
hole.\n
LOCATION:https://researchseminars.org/talk/IPMHolographySeminar/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lampros Lamprou (UBC)
DTSTART:20210907T053000Z
DTEND:20210907T063000Z
DTSTAMP:20260422T212934Z
UID:IPMHolographySeminar/11
DESCRIPTION:Title: Falling inside holographic black holes\nby Lampros Lampr
ou (UBC) as part of IPM Holography Virtual Seminars\n\n\nAbstract\nI will
present a bulk reconstruction technique in AdS/CFT suitable for addressing
a facet of the black hole information problem: how to unambiguously predi
ct the results of measurements accessible to an infalling observer in the
black hole interior.\n
LOCATION:https://researchseminars.org/talk/IPMHolographySeminar/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mark Mezei (SCGP\, Stony Brook)
DTSTART:20210914T123000Z
DTEND:20210914T133000Z
DTSTAMP:20260422T212934Z
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 Seminars
\n\n\nAbstract\nUnderstanding the fate of semi-classical black hole soluti
ons at very late times is one of the most important open questions in quan
tum gravity. In this talk\, we provide a path integral definition of the v
olume of the black hole interior and study it at arbitrarily late times fo
r black holes in various models of two-dimensional gravity. Because of a n
ovel universal cancellation between the contributions of the semi-classica
l black hole spectrum and some of its non-perturbative corrections\, we fi
nd that\, after a linear growth at early times\, the length of the interio
r saturates at a time\, and towards a value\, that is exponentially large
in the entropy of the black hole. This provides a non-perturbative confirm
ation of the complexity equals volume proposal since complexity is also ex
pected to plateau at the same value and at the same time.\n
LOCATION:https://researchseminars.org/talk/IPMHolographySeminar/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mikhail Khramtsov (Vrije Universiteit Brussel)
DTSTART:20210928T133000Z
DTEND:20210928T143000Z
DTSTAMP:20260422T212934Z
UID:IPMHolographySeminar/13
DESCRIPTION:Title: Submerging islands through thermalization\nby Mikhail Kh
ramtsov (Vrije Universiteit Brussel) as part of IPM Holography Virtual Sem
inars\n\n\nAbstract\nWe illustrate scenarios in which Hawking radiation co
llected in finite regions of a reservoir provides temporary access to the
interior of eternal black holes through transient entanglement "islands".
Whether these islands appear and the amount of time for which they dominat
e - sometimes giving way to a thermalization transition - is controlled by
the amount of radiation we probe. In the first scenario\, two reservoirs
are coupled to an eternal black hole. The second scenario involves two hol
ographic quantum gravitating systems at different temperatures interacting
through a Rindler-like reservoir\, which acts as a heat engine maintainin
g thermal equilibrium. This situation describes two eternal black holes ra
diating into each other through a shared reservoir. We will also discuss t
he analogous effect in the evaporating AdS2 black hole.\n
LOCATION:https://researchseminars.org/talk/IPMHolographySeminar/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Pranjal Nayak (Geneva University)
DTSTART:20211019T133000Z
DTEND:20211019T143000Z
DTSTAMP:20260422T212934Z
UID:IPMHolographySeminar/14
DESCRIPTION:Title: Wormholes in Quantum Ergodicity\nby Pranjal Nayak (Genev
a University) as part of IPM Holography Virtual Seminars\n\n\nAbstract\nFo
r a generic quantum many-body system\, the quantum ergodic regime is defin
ed as the limit in which the spectrum of the system resembles that of a ra
ndom matrix theory (RMT) in the corresponding symmetry class. In this talk
I will discuss the time dependence of correlation functions of operators
in the SYK model\, in the ergodic limit as well as their approach to the e
rgodic limit which is controlled by non-universal massive modes. An effect
ive field theory (EFT) corresponding to the causal symmetry and its breaki
ng describes the ergodic phase. I will discuss the topological expansion o
f the resulting Goldstone-mode theory where the leading non-trivial topolo
gies give rise to the universal ramp seen in correlation functions. Furthe
rmore we analytically capture the plateau behaviour by taking into account
the contribution of a second saddle point. These results explicitly estab
lish the validity of the EFT description in the SYK-class of models\, star
ting from their microscopic description. I will discuss the tower of massi
ve modes above the Goldstone sector that govern how the ergodic EFT phase
is approached and derive the relevant Thouless time scales.\n\nIn the seco
nd part of the talk\, I will discuss the connections between the Eigenstat
e thermalisation hypothesis (ETH) and the Euclidean wormholes. Motivated b
y this connections I will discuss our proposal for ETH for charged operato
rs in quantum theories with global symmetries.\n
LOCATION:https://researchseminars.org/talk/IPMHolographySeminar/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jie-qiang Wu (UCSB)
DTSTART:20211026T133000Z
DTEND:20211026T143000Z
DTSTAMP:20260422T212934Z
UID:IPMHolographySeminar/15
DESCRIPTION:Title: Algebra of diffeomorphism invariant observables in Jackiw-Te
itelboim gravity\nby Jie-qiang Wu (UCSB) as part of IPM Holography Vir
tual Seminars\n\n\nAbstract\nDiffeomorphism symmetry is an intrinsic diffi
culty in gravitational theory\, which appears in\nalmost all of the questi
ons in gravity. As is well known\, the diffeomorphism symmetries in gravit
y should\nbe interpreted as gauge symmetries\, so only diffeomorphism inva
riant operators are physically\ninteresting. However\, because of the non-
linear effect of gravitational theory\, the results for\ndiffeomorphism in
variant operators are very limited.\nIn this work\, we focus on the Jackiw
-Teitelboim gravity in classical limit\, and use Peierls bracket (which is
\na linear response like computation of observables’ bracket) to compute
the algebra of a large class of\ndiffeomorphism invariant observables. Wi
th this algebra\, we can reproduce some recent results in\nJackiw-Teitelbo
im gravity including: traversable wormhole\, scrambling effect\, and SL(2)
charges. We can\nalso use it to clarify the question of when the creation
of an excitation deep in the bulk increases or\ndecreases the boundary en
ergy\, which is of crucial importance for the “typical state” version
of the\nfirewall paradox.\nIn the talk\, I will first give a brief introdu
ction of Peierls bracket\, and then use the Peierls bracket to\nstudy the
brackets between diffeomorphism invariant observables in Jackiw-Teitelboim
gravity. I will\nthen give two applications of this algebra: reproducing
the scrambling effect\, and studying the energy\nchange after creating an
excitation in the bulk.\n
LOCATION:https://researchseminars.org/talk/IPMHolographySeminar/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Krishan Saraswat (Perimeter Institute)
DTSTART:20211123T143000Z
DTEND:20211123T153000Z
DTSTAMP:20260422T212934Z
UID:IPMHolographySeminar/16
DESCRIPTION:Title: Spacing Statistics of Energy Spectra: Random Matrices\, Blac
k Hole Thermalization\, and Echoes\nby Krishan Saraswat (Perimeter Ins
titute) as part of IPM Holography Virtual Seminars\n\n\nAbstract\nRecent a
dvances in AdS/CFT suggest that the near-horizon dynamics of black holes c
an be described by unitary random matrix systems. Motivated by these devel
opments\, I will discuss how the energy spectrum of a system with a generi
c random Hamiltonian matrix affects its early and late time thermalization
behaviour using the spectral form factor (which captures the time-depende
nce of two-point correlation functions) and connect it to the discussion o
f gravitational wave echoes. In particular\, I will demonstrate that it is
possible for quantum chaotic systems to exhibit echoes if the energy spec
trum contains many clusters of eigenvalues which are regularly spaced from
each other. I will discuss the example of a randomly coupled oscillator s
ystem and show that at weak coupling the form factor exhibits echoes. I wi
ll speculate on the holographic interpretation of a system of weakly coupl
ed oscillators\, and give a heuristic picture of how they might describe t
he thermalization behaviour of a black hole geometry with a membrane that
cuts off the geometry at the stretched horizon. I will also discuss the ro
le that symmetries play in quantum chaotic systems that exhibit echoes.\n
LOCATION:https://researchseminars.org/talk/IPMHolographySeminar/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jonah Kudler-Flam (University of Chicago)
DTSTART:20211130T133000Z
DTEND:20211130T143000Z
DTSTAMP:20260422T212934Z
UID:IPMHolographySeminar/17
DESCRIPTION:Title: Distinguishability in Random States\, Eigenstates\, and Grav
ity\nby Jonah Kudler-Flam (University of Chicago) as part of IPM Holog
raphy Virtual Seminars\n\n\nAbstract\nRecently\, there has been significan
t progress in solving the black hole information problem from explicit cal
culations of the entropy of Hawking radiation\, confirming consistency of
gravity with unitarity. One aspect of the information problem left unresol
ved by entropy calculations is the distinguishability of different black h
ole microstates: why do different microstates appear to lead to the same f
inal (thermal) state? I will address this problem by studying the distingu
ishability of radiation coming from different black holes. In parallel\, I
will present a derivation of the subsystem eigenstate thermalization hypo
thesis for a class of chaotic many-body systems as well as generalizations
to tensor network states.\n
LOCATION:https://researchseminars.org/talk/IPMHolographySeminar/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Aasmund Folkestad (MIT)
DTSTART:20220118T133000Z
DTEND:20220118T143000Z
DTSTAMP:20260422T212934Z
UID:IPMHolographySeminar/18
DESCRIPTION:Title: General Bounds on Holographic Complexity\nby Aasmund Fol
kestad (MIT) as part of IPM Holography Virtual Seminars\n\n\nAbstract\nIn
this talk\, we present novel rigorous bounds on maximal volume slices in a
symptotically AdS spacetimes. Under the Complexity=Volume conjecture\, the
se results imply that the CFT vacuum is the simplest state\, provided we a
ssume the weak energy condition and no compact bulk dimensions. Next\, we
show that compact dimensions or tachyonic scalar fields can violate our r
esult\, giving rise to distinct effects that should be reproduced by any p
roposed dual to maximal volumes. Finally\, we present a speed limit on th
e growth of volumes in terms of spacetime mass\, which under the CV conjec
ture constitutes a holographic proof of Lloyd's bound for a class of space
times.\n
LOCATION:https://researchseminars.org/talk/IPMHolographySeminar/18/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Batoul Banihashemi (University of Maryland)
DTSTART:20220517T123000Z
DTEND:20220517T133000Z
DTSTAMP:20260422T212934Z
UID:IPMHolographySeminar/19
DESCRIPTION:Title: Thermodynamic ensembles with cosmological horizons\nby B
atoul Banihashemi (University of Maryland) as part of IPM Holography Virtu
al Seminars\n\n\nAbstract\nThe entropy of a de Sitter horizon was derived
long ago by Gibbons and Hawking via a gravitational partition function. Si
nce there is no boundary at which to define the temperature or energy of t
he ensemble\, the statistical foundation of their approach has remained ob
scure. To place the statistical ensemble on a firm footing we introduce an
artificial “York boundary”\, with either canonical or microcanonical
boundary conditions\, as has been done previously for black hole ensembles
. The partition function and the density of states are expressed as integr
als over paths in the constrained\, spherically reduced phase space of pur
e 3+1 dimensional gravity with a positive cosmological constant. The canon
ical ensemble includes a patch of spacetime without horizon\, as well as c
onfigurations containing a black hole or a cosmological horizon. In this t
alk I briefly discuss issues related to the domain and contour of integrat
ion in the path integral\, and justify the adopted choices for those as fa
r as possible. I also explain thermodynamic phases and (in)stability\, and
discuss an evolving reservoir model that can stabilize the cosmological h
orizon in the canonical ensemble. Finally\, I explain how the Gibbons-Hawk
ing partition function on the 4-sphere can be derived as a limit of well-d
efined thermodynamic ensembles.\n
LOCATION:https://researchseminars.org/talk/IPMHolographySeminar/19/
END:VEVENT
END:VCALENDAR