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BEGIN:VEVENT
SUMMARY:Marija Tomasevic (Barcelona)
DTSTART:20200505T224000Z
DTEND:20200505T234000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/1
DESCRIPTION:Title: Strong cosmic censorship in the BTZ black hole\nby Marija T
omasevic (Barcelona) as part of UC Berkeley - BCTP string seminar\n\n\nAbs
tract\nRecently it has been shown that quantum fields can be regular on th
e inner\, Cauchy horizon of a rotating BTZ black hole\, which appears to i
ndicate a failure of strong cosmic censorship. We argue that\, instead\, w
hat these results imply is that the inner horizon remains non-singular whe
n leading-order backreaction of the quantum fields is computed\, but\, aft
er next-order backreaction is accounted for\, it will become singular. The
n\, strong cosmic censorship will be enforced in the BTZ black hole. We su
pport our claims using a four-dimensional holographic dual of the system\,
which connects the instability of the inner horizon of the BTZ black hole
to that of Kerr-type black holes.\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Netta Engelhardt (MIT)
DTSTART:20200512T224000Z
DTEND:20200512T234000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/2
DESCRIPTION:Title: Models of Black Hole Evaporation\nby Netta Engelhardt (MIT)
as part of UC Berkeley - BCTP string seminar\n\n\nAbstract\nI will discus
s several models of evaporating AdS black holes. In all models\, it is pos
sible to use the holographic entanglement entropy prescription to compute
the dependence of entropy on time. In two cases\, the dynamics are unitary
\, and a semiclassical calculation is sufficient to show this. In the thir
d toy model\, the dynamics are manifestly non-unitary\; in this last case
the holographic entropy calculation yields a non-unitary Hawking curve for
the entropy as a function of time.\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Juan Maldacena (IAS)
DTSTART:20200602T224000Z
DTEND:20200602T234000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/4
DESCRIPTION:Title: Magnetic black holes\nby Juan Maldacena (IAS) as part of UC
Berkeley - BCTP string seminar\n\n\nAbstract\nWe discuss aspects of magne
tically charged black holes in the Standard Model. For black holes smaller
than a tennis ball\, the electroweak symmetry is restored in the near hor
izon region. The lowest Landau level for the charged fermions leads to a l
arge number effectively light degrees of freedom\, which greatly enhance t
he effects of Hawking radiation. They are interesting primordial black hol
e candidates.\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Adam Bouland (UC Berkeley)
DTSTART:20200526T224000Z
DTEND:20200526T234000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/5
DESCRIPTION:Title: Computational pseudorandomness\, the wormhole growth paradox\,
and constraints on the AdS/CFT duality\nby Adam Bouland (UC Berkeley)
as part of UC Berkeley - BCTP string seminar\n\n\nAbstract\nA fundamental
issue in the AdS/CFT correspondence is the wormhole growth paradox. Susski
nd’s conjectured resolution of the paradox was to equate the volume of t
he wormhole with the circuit complexity of its dual quantum state in the C
FT. We study the ramifications of this conjecture from a complexity-theore
tic perspective. Specifically we give evidence for the existence of comput
ationally pseudorandom states in the CFT\, and argue that wormhole volume
is measureable in a non-physical but computational sense\, by amalgamating
the experiences of multiple observers in the wormhole. In other words the
conjecture equates a quantity which is difficult to compute with one whic
h is easy to compute. The pseudorandomness argument further implies that t
his is a necessary feature of any resolution of the wormhole growth parado
x\, not just of Susskind’s Complexity=Volume conjecture. As a corollary
we conclude that either the AdS/CFT dictionary map must be exponentially c
omplex\, or the quantum Extended Church-Turing thesis must be false in qua
ntum gravity.\n\nThis talk is based on joint work with Bill Fefferman and
Umesh Vazirani. arXiv:1910.14646\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mark Van Raamsdonk (UBC)
DTSTART:20200609T224000Z
DTEND:20200609T234000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/6
DESCRIPTION:Title: Holo-ween\nby Mark Van Raamsdonk (UBC) as part of UC Berkel
ey - BCTP string seminar\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alex Maloney (McGill)
DTSTART:20200616T224000Z
DTEND:20200616T234000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/7
DESCRIPTION:Title: Gravity from Averaging CFTs\nby Alex Maloney (McGill) as pa
rt of UC Berkeley - BCTP string seminar\n\n\nAbstract\nI will explore the
idea that certain theories of gravity in Anti-de\nSitter space are dual to
an average over an ensemble of quantum\ntheories\, rather than to a speci
fic quantum theory. I will describe\nan average over Narain’s family of
two-dimensional conformal field\ntheories which describe free bosons on a
torus\, and compute the\npartition function using the Siegel-Weil formula
. The result takes\nthe form of a sum over geometries as one would expect
in a theory of\ngravity. But the gravitational theory looks more like a
Chern-Simons\ntheory than like Einstein gravity.\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jinzhao Wang (ETH Zurich)
DTSTART:20200714T210000Z
DTEND:20200714T220000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/8
DESCRIPTION:Title: Outer entropy = Bartnik-Bray inner mass\, and the gravitational
ant conjecture\nby Jinzhao Wang (ETH Zurich) as part of UC Berkeley -
BCTP string seminar\n\n\nAbstract\nEntropy and energy are found to be clo
sely tied on our quest for quantum gravity. We point out an interesting co
nnection between the recently proposed outer entropy\, a coarse-grained en
tropy defined for a compact spacetime domain motivated by the holographic
duality\, and the Bartnik-Bray quasilocal mass long known in the mathemati
cs community. In both scenarios\, one seeks an optimal spacetime fill-in o
f a given closed\, connected\, spacelike\, codimension-two boundary. We sh
ow that for an outer-minimizing mean-convex surface\, the Bartnik-Bray inn
er mass matches exactly with the irreducible mass corresponding to the out
er entropy. The equivalence implies that the area laws derived from the ou
ter entropy are mathematically equivalent as the monotonicity property of
the quasilocal mass. It also gives rise to new bounds between entropy and
the gravitational energy\, which naturally gives the gravitational counter
part to Wall's ant conjecture. We also observe that the equality can be ac
hieved in a conformal flow of metrics\, which is structurally similar to t
he Ceyhan-Faulkner proof of the ant conjecture. We compute the small spher
e limit of the outer entropy and it is proportional to the bulk stress ten
sor as one would expect for a quasilocal mass.\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Geoff Penington
DTSTART:20200728T224000Z
DTEND:20200728T234000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/9
DESCRIPTION:Title: Leading order corrections to the quantum extremal surface presc
ription\nby Geoff Penington as part of UC Berkeley - BCTP string semin
ar\n\n\nAbstract\nThe QES prescription is a rule for computing entanglemen
t entropies in quantum gravity that has become one of the central tools in
holography. In particular\, it was crucial to recent progress on understa
nding the Page curve for evaporating black holes. However\, as I will show
\, a naïve application of the QES prescription for arbitrary bulk states
is paradoxical\, even at leading order. Instead\, it needs to be replaced
by a more refined prescription based on tools from one-shot quantum Shanno
n theory. I will show how the failure of the QES prescription come from a
failure of the assumptions in the Lewkowycz-Maldacena derivation\, and how
a more careful replica trick derivation correctly computes the leading or
der corrections.\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Graeme Stewart Baird Smith (Colorado)
DTSTART:20200908T224000Z
DTEND:20200908T234000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/10
DESCRIPTION:Title: Multipartite Optimized Correlation Measures and Holography
\nby Graeme Stewart Baird Smith (Colorado) as part of UC Berkeley - BCTP s
tring seminar\n\n\nAbstract\nI’ll discuss ways to quantify multipartite
correlations\, in quantum information and in holography. We’ll focus on
optimized correlation measures: linear combinations of entropies minimized
over all possible purifications of a state that also satisfy monotonicity
conditions. These contain far more information about correlations than en
tanglement entropy alone. We give a procedure to derive such quantities\,
and construct a menagerie of symmetric optimized correlation measures on t
hree parties. These include tripartite generalizations of the entanglement
of purification\, the squashed entanglement\, and the recently introduced
Q-correlation and R-correlation. Some correlation measures vanish only on
product states\, and thus quantify both classical and quantum correlation
s\; others vanish on any separable state\, capturing quantum correlations
alone. We then use a procedure motivated by the surface-state corresponden
ce to construct holographic duals for the correlation measures as linear c
ombinations of bulk surfaces. The geometry of the surfaces can preserve\,
partially break\, or fully break the symmetry of the correlation measure.
The optimal purification is encoded in the locations of certain points\, w
hose locations are fixed by constraints on the areas of combinations of su
rfaces. This gives a new concrete connection between information theoretic
quantities evaluated on a boundary state and detailed geometric propertie
s of its dual.\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Chitraang Murdia (UC Berkeley)
DTSTART:20200915T224000Z
DTEND:20200915T234000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/11
DESCRIPTION:Title: Coarse-Graining Holographic States and Semiclassical Bulk Flow
\nby Chitraang Murdia (UC Berkeley) as part of UC Berkeley - BCTP stri
ng seminar\n\n\nAbstract\nI will describe a bulk procedure that generates
a sequence of coarse-grained holographic states by disentangling degrees o
f freedom at short distances. This is manifested as a flow in the bulk whi
ch approaches quantum extremal surfaces. This procedure generalizes an ear
lier classical construction by including bulk quantum corrections.\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Matthew Dodelson (IPMU)
DTSTART:20200922T224000Z
DTEND:20200922T234000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/12
DESCRIPTION:Title: Singularities of Thermal Correlators at Strong Coupling\nb
y Matthew Dodelson (IPMU) as part of UC Berkeley - BCTP string seminar\n\n
\nAbstract\nI will describe work in progress with Ooguri on the singularit
ies of the two point function at finite temperature in a conformal field t
heory in more than two dimensions. At weak coupling the only singularity i
s on the light cone\, but in the large N\, large lambda regime a new singu
larity emerges. This new singularity corresponds to a null geodesic in the
AdS/Schwarzschild black hole\, which may wrap the photon sphere many time
s. After deriving this result\, I will discuss the resolution of these sin
gularities by stringy tidal effects at finite lambda. The basic tool I wil
l use is to take the Penrose limit around a given null geodesic\, and then
use the solubility of the string theory in this background. I will also d
iscuss applications to rotating black holes.\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lampros Lamprou (MIT/UBC)
DTSTART:20200929T224000Z
DTEND:20200929T234000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/13
DESCRIPTION:Title: Inside the Hologram: The bulk observer's experience\nby La
mpros Lamprou (MIT/UBC) as part of UC Berkeley - BCTP string seminar\n\nAb
stract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Monica Kang (Caltech)
DTSTART:20201006T224000Z
DTEND:20201006T234000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/14
DESCRIPTION:Title: A GNS story of holographic baby universes\nby Monica Kang
(Caltech) as part of UC Berkeley - BCTP string seminar\n\n\nAbstract\nI wi
ll introduce a GNS construction as a formalism to study baby universes. Th
is naturally shifts the primordial role to the algebra of observables rath
er than the Hilbert spaces. I will explicitly form baby universe operation
s and utilize them to build baby universe algebras. Using these ingredient
s\, I will construct the baby universe Hilbert spaces. I will highlight th
at this approach will give an understanding of the miraculous cancellation
as a natural result from the character theory. I will illustrate its phys
ics by giving two different physical settings as examples.\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Antony Speranza (Perimeter)
DTSTART:20201013T224000Z
DTEND:20201013T234000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/15
DESCRIPTION:Title: Anomalies in gravitational charge algebras of null boundaries
and black hole entropy\nby Antony Speranza (Perimeter) as part of UC B
erkeley - BCTP string seminar\n\n\nAbstract\nI will discuss how the centra
l charges appearing in near-horizon symmetry algebras arise from an anomal
ous transformation of the null boundary term in the gravitational action.
This parallels the way in which the holographic Weyl anomaly appears in A
dS/CFT\, with the ambiguity in the normalization of the null generator bei
ng the analogue of the choice of Weyl frame. As an application\, I will a
nalyze a generalization of the near-horizon Virasoro symmetries of Haco\,
Hawking\, Perry\, and Strominger\, and give a systematic derivation of the
Wald-Zoupas fluxes and central charges. In particular\, I will discuss a
way to define the quasilocal charges unambiguously\, and show that the ce
ntral charge computed by the charge algebra is directly related to the hor
izon entropy via the Cardy formula.\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lorenz Eberhardt (IAS)
DTSTART:20201026T173000Z
DTEND:20201026T183000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/16
DESCRIPTION:Title: Partition functions of the tensionless string\nby Lorenz E
berhardt (IAS) as part of UC Berkeley - BCTP string seminar\n\n\nAbstract\
nI discuss string theory on AdS3xS3xT4 in the tensionless limit\, with one
unit of NS-NS flux. This theory is conjectured to be dual to the symmetri
c product orbifold CFT. I show how to compute the full string partition fu
nction on various locally AdS3 backgrounds\, such as thermal AdS3\, the BT
Z black and conical defects\, and find that it is independent of the actua
l background\, but only depends on the boundary geometry. Consequently\, r
eproducing the boundary partition function does not require a sum over bul
k geometries\, but rather agrees with the string partition function on any
bulk geometry with the appropriate boundary. I argue that the same mechan
ism shows the factorization of the bulk partition function when geometries
with disconnected boundaries are considered.\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jordan Cotler (Harvard)
DTSTART:20201104T234000Z
DTEND:20201105T004000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/17
DESCRIPTION:Title: Euclidean Wormholes and Gravitational Constrained Instantons\nby Jordan Cotler (Harvard) as part of UC Berkeley - BCTP string semina
r\n\n\nAbstract\nWe discover a wide range of new nonperturbative effects i
n quantum gravity\, namely moduli spaces of constrained saddles (often cal
led constrained instantons) of the Einstein-Hilbert action. We find these
in all spacetime dimensions\, for AdS and dS. Many can be written in clo
sed form\, and some are shown to be quadratically stable. In the Euclidea
n AdS setting\, these constrained saddles correspond to Euclidean wormhole
s. In 3D AdS\, where the gravitational path integral is more tractable\,
we study these Euclidean wormholes and show that they encode the energy le
vel statistics of microstates of BTZ black holes. Furthermore\, these sta
tistics precisely agree with a quantitative prediction from random matrix
theory.\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Rob Myers (Perimeter Institute)
DTSTART:20201201T234000Z
DTEND:20201202T004000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/18
DESCRIPTION:Title: Quantum Extremal Islands Made Easy\nby Rob Myers (Perimete
r Institute) as part of UC Berkeley - BCTP string seminar\n\n\nAbstract\nW
e illustrate the appearance of quantum extremal islands in holographic set
ups in higher dimensions. We emphasize the close parallel with the behavio
ur of holographic entanglement entropy in more familiar settings.\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/18/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mykhaylo Usatyuk (UC Berkeley)
DTSTART:20201215T234000Z
DTEND:20201216T004000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/19
DESCRIPTION:Title: Dilaton-gravity\, deformations of the minimal string\, and mat
rix models\nby Mykhaylo Usatyuk (UC Berkeley) as part of UC Berkeley -
BCTP string seminar\n\n\nAbstract\nA large class of two-dimensional dilat
on-gravity theories in asymptotically AdS2 spacetimes are holographically
dual to a matrix integral\, interpreted as an ensemble average over Hamilt
onians. Viewing these theories as Jackiw-Teitelboim gravity with a gas of
defects\, I will show how to extend this duality to a broader class of dil
aton potentials compared to previous work by including conical defects wit
h small deficit angles. In order to do this\, I show that these theories a
re equal to the large p limit of a natural deformation of the (2\, p) mini
mal string theory.\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/19/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tom Rudelius (UC Berkeley)
DTSTART:20210119T234000Z
DTEND:20210120T004000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/20
DESCRIPTION:Title: Generalizations of Generalized Global Symmetries and the Swamp
land\nby Tom Rudelius (UC Berkeley) as part of UC Berkeley - BCTP stri
ng seminar\n\n\nAbstract\nStandard lore holds that a consistent theory of
quantum gravity cannot have exact global symmetries. In this talk\, we wil
l show how simple generalizations of this lore can be used to motivate a n
umber of other well-supported "Swampland conjectures\," thereby highlighti
ng the importance of global symmetries for understanding universal feature
s of quantum gravity.\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/20/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Zhenbin Yang (Stanford)
DTSTART:20210202T234000Z
DTEND:20210203T004000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/21
DESCRIPTION:Title: A violation of global symmetries from replica wormholes and th
e fate of black hole remnants\nby Zhenbin Yang (Stanford) as part of U
C Berkeley - BCTP string seminar\n\n\nAbstract\nWe show that the presence
of replica wormholes in the Euclidean path integral of gravity leads to a
non-perturbative violation of any global symmetry present in the low-energ
y description of quantum gravity. Explicitly\, we compute the scattering p
robability between different charged states in several low-dimensional mod
els of quantum gravity and find a non-vanishing answer. This suggests that
the set of all charged states is typically over-complete\, which has dras
tic consequences for the fate of black hole remnants that could carry a gl
obal symmetry charge. In the holographic context\, we argue that the prese
nce of such a symmetry in the effective description of the bulk should app
ear on the boundary as an emergent global symmetry after ensemble averagin
g.\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/21/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Joaquin Turiaci (UC Santa Barbara)
DTSTART:20210209T234000Z
DTEND:20210210T004000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/22
DESCRIPTION:Title: The black hole spectrum in (super)gravity\nby Joaquin Turi
aci (UC Santa Barbara) as part of UC Berkeley - BCTP string seminar\n\n\nA
bstract\nThe talk will focus on the spectrum of near-extremal black holes
in gravity and near-BPS black holes in supergravity. For concreteness\, we
will study cases in asymptotically four-dimensional flat space and three-
dimensional Anti-de Sitter. This will be done by analyzing quantum effects
near the horizon captured by an emergent Jackiw-Teitelboim mode at low te
mperatures. This will allow us to systematically study questions such as t
he extremal degeneracy and the size of the gap in the black hole spectrum\
, which can be compared to some string theory constructions.\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/22/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Andreas Blommaert (Stanford)
DTSTART:20210126T234000Z
DTEND:20210127T004000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/23
DESCRIPTION:Title: Wormholes\, eigenbranes and ensembles\nby Andreas Blommaer
t (Stanford) as part of UC Berkeley - BCTP string seminar\n\n\nAbstract\nW
e discuss the role of wormholes and eigenbranes in reconciling geometry wi
th quantum mechanics\, working within two dimensional dilaton gravity. Fir
st\, we review how wormholes enable geometry to accurate capture averaged
properties of late time correlators of chaotic quantum systems. Because th
ese are averaged properties\, naively\, wormholes in gravitational theorie
s suggest some ensemble interpretation of those gravitational theories\, h
ere embodied by some matrix integral. We then explain that the geometrical
description of individual draws of this ensemble means considering the sa
me gravitational theory on specific background spacetime branes. These eig
enbranes deform the gravity theory precisely like in open closed string du
ality and collapse the ensemble to one quantum system.\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/23/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tadashi Takayanagi (YITP\, Kyoto)
DTSTART:20210309T234000Z
DTEND:20210310T004000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/25
DESCRIPTION:Title: A New Generalization of Entanglement Entropy: Pseudo Entropy\nby Tadashi Takayanagi (YITP\, Kyoto) as part of UC Berkeley - BCTP str
ing seminar\n\n\nAbstract\nPseudo-entropy is an interesting quantity with
a simple gravity dual\, \nwhich generalizes entanglement entropy such that
it depends on \nboth an initial and a final state. In this talk we start
with an \nintroduction of this new quantity explaining its basic propertie
s.\nNext we will study its gravity dual. Finally\, we will present recent\
nnumerical results of this quantity in a free scalar field theory\nand in
a spin system\, which imply that pseudo entropy can serve as a new \nquant
um order parameter. This talk is based on \narXiv:2005.13801 and arXiv:201
1.09648.\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/25/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tom Hartman (Cornell)
DTSTART:20210316T224000Z
DTEND:20210316T234000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/26
DESCRIPTION:Title: Islands in Cosmology\nby Tom Hartman (Cornell) as part of
UC Berkeley - BCTP string seminar\n\n\nAbstract\nBlack hole interiors shar
e some features with cosmology: both have time dependence\, singularities\
, horizons\, and very large entropy density. In this talk I will discuss w
hether recent progress on understanding the black hole interior and the Pa
ge curve\, based on quantum extremal islands\, gives new insight into quan
tum cosmology.\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/26/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Netta Engelhardt (MIT)
DTSTART:20210323T224000Z
DTEND:20210323T234000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/27
DESCRIPTION:Title: Cosmic Censorship in AdS/CFT\nby Netta Engelhardt (MIT) as
part of UC Berkeley - BCTP string seminar\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/27/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alex May (UBC)
DTSTART:20210504T224000Z
DTEND:20210504T234000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/28
DESCRIPTION:Title: Quantum tasks require islands on the brane\nby Alex May (U
BC) as part of UC Berkeley - BCTP string seminar\n\n\nAbstract\nIn recent
work\, it was argued that quantum computations with inputs and outputs dis
tributed in spacetime\, or quantum tasks\, impose constraints on entanglem
ent in holographic theories. The resulting constraint was named the connec
ted wedge theorem and can be verified by a direct bulk proof using focusin
g arguments in general relativity. In this article we extend this work to
the context of AdS/BCFT\, where an end-of-the-world brane is present in th
e bulk. By considering quantum tasks which exploit information localized t
o the brane\, we find a new connected wedge theorem. We apply this theorem
to brane models of black holes\, where it relates the formation of island
s in the Ryu-Takayanagi formula to causal features of the ambient spacetim
e. In particular\, we find that if the black hole interior is causally con
nected to the radiation system through the ambient spacetime\, then an isl
and forms. For constant tension branes in pure AdS the converse also holds
.\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/28/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Henry Maxfield (UCSB)
DTSTART:20210330T224000Z
DTEND:20210330T234000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/29
DESCRIPTION:Title: Baby Universes and Worldline Field Theories\nby Henry Maxf
ield (UCSB) as part of UC Berkeley - BCTP string seminar\n\n\nAbstract\nTo
pology changing processes have played a central role in recent development
s in quantum gravity\, and have been argued to lead to an abelian algebra
of superselected observables. I will discuss one-dimensional theories of q
uantum gravity in this context. This invites comparison with a worldline f
ormalism of QFT\, with its non-abelian algebra of quantum fields. This app
arent tension is resolved by considering the different choices to be made
when constructing Hilbert spaces for quantum gravity and QFT.\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/29/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Petr Horava (UC Berkeley)
DTSTART:20210420T224000Z
DTEND:20210420T234000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/30
DESCRIPTION:Title: Large N Expansion and String Theory Out of Equilibrium\nby
Petr Horava (UC Berkeley) as part of UC Berkeley - BCTP string seminar\n\
nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/30/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Simeon Hellerman (IPMU)
DTSTART:20210406T224000Z
DTEND:20210406T234000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/31
DESCRIPTION:Title: Quantum Information Theory of the Gravitational Anomaly\nb
y Simeon Hellerman (IPMU) as part of UC Berkeley - BCTP string seminar\n\n
\nAbstract\nI will show that the notion of quantum entanglement is not\nde
fined for gravitationally anomalous two-dimensional theories\,\nbecause th
ey do not admit a local tensor factorization of the Hilbert\nspace into lo
cal Hilbert spaces. Qualitatively\, the modular flow\ncannot act consisten
tly and unitarily in a finite region\, if there are\ndifferent numbers of
states with a given energy traveling in the two\nopposite directions. I wi
ll make this precise by decomposing it into\ntwo observations: First\, a t
wo-dimensional conformal field theory\nadmits a consistent quantization on
a space with boundary only if it\nis not anomalous. Second\, a local tens
or factorization always leads to\na definition of consistent\, unitary\, e
nergy-preserving boundary\ncondition. As a corollary I will establish a ge
neralization of the\nNielsen–Ninomiya theorem to all two-dimensional uni
tary local quantum\nfield theories: No continuum quantum field theory in t
wo dimensions\ncan admit a lattice regulator unless its gravitational anom
aly\nvanishes. I will advocate that these points be used to reinterpret th
e\ngravitational anomaly quantum-information-theoretically\, as a\nfundame
ntal obstruction to the localization of quantum information.\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/31/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gary Horowitz (UCSB)
DTSTART:20210413T224000Z
DTEND:20210413T234000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/32
DESCRIPTION:Title: Boundary Causality Violating Metrics in Holography\nby Gar
y Horowitz (UCSB) as part of UC Berkeley - BCTP string seminar\n\n\nAbstra
ct\nThe full bulk path integral in a Lorentzian formulation of holography
includes metrics that violate boundary causality. This leads to the follow
ing puzzle: The commutator of two field theory operators at spacelike-sepa
rated points on the boundary must vanish. However\, if these points are ca
usally related in a bulk metric\, then the bulk calculation of the commuta
tor will be nonzero. It would appear that the integral over all metrics of
this commutator must vanish exactly for holography to hold. This is puzzl
ing since it must also be true if the commutator is multiplied by any othe
r operator. We give a prescription for the bulk path integral in which res
olves this puzzle. In this approach\, the bulk dual of the boundary commut
ator is not the limit of the naive bulk commutator.\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/32/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Herman Verlinde (Princeton)
DTSTART:20210427T224000Z
DTEND:20210427T234000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/33
DESCRIPTION:Title: Towards a string dual of SYK\nby Herman Verlinde (Princeto
n) as part of UC Berkeley - BCTP string seminar\n\n\nAbstract\nI present a
proposal for how the SYK model can be realized within string theory. Star
ting from the matrix model description of the minimal string\, I show that
the partition function on a configuration of Q FZZT branes takes the form
of a matrix version of the SYK model. The SYK fermions arise from open s
trings on brane intersections. I describe how time emerges upon taking the
continuum limit and comment on the role of ensemble averaging in low dime
nsional holography.\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/33/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ben Freivogel (University of Amsterdam)
DTSTART:20210510T173000Z
DTEND:20210510T183000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/34
DESCRIPTION:Title: Wormholes calculate averages over states\nby Ben Freivogel
(University of Amsterdam) as part of UC Berkeley - BCTP string seminar\n\
n\nAbstract\nI will show that wormholes naturally arise as the gravity dua
l of an average over different states within a single conformal field theo
ry. These wormholes give a simple way to diagnose how typical pure states
differ from the thermal density matrix. Based on work to appear with D. Ni
kolakopoulou and A. Rotundo.\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/34/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Steve Shenker (Stanford)
DTSTART:20210907T224000Z
DTEND:20210907T234000Z
DTSTAMP:20260404T094319Z
UID:BCTP_string/35
DESCRIPTION:Title: Wormholes without averaging\nby Steve Shenker (Stanford) a
s part of UC Berkeley - BCTP string seminar\n\n\nAbstract\nWe discuss the
resolution of the factorization puzzle in AdS/CFT in the context of a simp
le version of the SYK model. (Joint work with Phil Saad\, Douglas Stanford
and Shunyu Yao.)\n
LOCATION:https://stable.researchseminars.org/talk/BCTP_string/35/
END:VEVENT
END:VCALENDAR