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BEGIN:VEVENT
SUMMARY:Marija Tomasevic (Barcelona)
DTSTART;VALUE=DATE-TIME:20200505T224000Z
DTEND;VALUE=DATE-TIME:20200505T234000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/1
DESCRIPTION:Title: Strong cosmic censorship in the BTZ black hole\nby Marija Tomasevi
c (Barcelona) as part of UC Berkeley - BCTP string seminar\n\n\nAbstract\n
Recently it has been shown that quantum fields can be regular on the inner
\, Cauchy horizon of a rotating BTZ black hole\, which appears to indicate
a failure of strong cosmic censorship. We argue that\, instead\, what the
se results imply is that the inner horizon remains non-singular when leadi
ng-order backreaction of the quantum fields is computed\, but\, after next
-order backreaction is accounted for\, it will become singular. Then\, str
ong cosmic censorship will be enforced in the BTZ black hole. We support o
ur claims using a four-dimensional holographic dual of the system\, which
connects the instability of the inner horizon of the BTZ black hole to tha
t of Kerr-type black holes.\n
LOCATION:https://researchseminars.org/talk/BCTP_string/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Netta Engelhardt (MIT)
DTSTART;VALUE=DATE-TIME:20200512T224000Z
DTEND;VALUE=DATE-TIME:20200512T234000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/2
DESCRIPTION:Title: Models of Black Hole Evaporation\nby Netta Engelhardt (MIT) as par
t of UC Berkeley - BCTP string seminar\n\n\nAbstract\nI will discuss sever
al models of evaporating AdS black holes. In all models\, it is possible t
o use the holographic entanglement entropy prescription to compute the dep
endence of entropy on time. In two cases\, the dynamics are unitary\, and
a semiclassical calculation is sufficient to show this. In the third toy m
odel\, the dynamics are manifestly non-unitary\; in this last case the hol
ographic entropy calculation yields a non-unitary Hawking curve for the en
tropy as a function of time.\n
LOCATION:https://researchseminars.org/talk/BCTP_string/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Juan Maldacena (IAS)
DTSTART;VALUE=DATE-TIME:20200602T224000Z
DTEND;VALUE=DATE-TIME:20200602T234000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/4
DESCRIPTION:Title: Magnetic black holes\nby Juan Maldacena (IAS) as part of UC Berkel
ey - BCTP string seminar\n\n\nAbstract\nWe discuss aspects of magnetically
charged black holes in the Standard Model. For black holes smaller than a
tennis ball\, the electroweak symmetry is restored in the near horizon re
gion. The lowest Landau level for the charged fermions leads to a large nu
mber effectively light degrees of freedom\, which greatly enhance the effe
cts of Hawking radiation. They are interesting primordial black hole candi
dates.\n
LOCATION:https://researchseminars.org/talk/BCTP_string/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Adam Bouland (UC Berkeley)
DTSTART;VALUE=DATE-TIME:20200526T224000Z
DTEND;VALUE=DATE-TIME:20200526T234000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/5
DESCRIPTION:Title: Computational pseudorandomness\, the wormhole growth paradox\, and con
straints on the AdS/CFT duality\nby Adam Bouland (UC Berkeley) as part
of UC Berkeley - BCTP string seminar\n\n\nAbstract\nA fundamental issue i
n the AdS/CFT correspondence is the wormhole growth paradox. Susskind’s
conjectured resolution of the paradox was to equate the volume of the worm
hole with the circuit complexity of its dual quantum state in the CFT. We
study the ramifications of this conjecture from a complexity-theoretic per
spective. Specifically we give evidence for the existence of computational
ly pseudorandom states in the CFT\, and argue that wormhole volume is meas
ureable in a non-physical but computational sense\, by amalgamating the ex
periences of multiple observers in the wormhole. In other words the conjec
ture equates a quantity which is difficult to compute with one which is ea
sy to compute. The pseudorandomness argument further implies that this is
a necessary feature of any resolution of the wormhole growth paradox\, not
just of Susskind’s Complexity=Volume conjecture. As a corollary we conc
lude that either the AdS/CFT dictionary map must be exponentially complex\
, or the quantum Extended Church-Turing thesis must be false in quantum gr
avity.\n\nThis talk is based on joint work with Bill Fefferman and Umesh V
azirani. arXiv:1910.14646\n
LOCATION:https://researchseminars.org/talk/BCTP_string/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mark Van Raamsdonk (UBC)
DTSTART;VALUE=DATE-TIME:20200609T224000Z
DTEND;VALUE=DATE-TIME:20200609T234000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/6
DESCRIPTION:Title: Holo-ween\nby Mark Van Raamsdonk (UBC) as part of UC Berkeley - BC
TP string seminar\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/BCTP_string/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alex Maloney (McGill)
DTSTART;VALUE=DATE-TIME:20200616T224000Z
DTEND;VALUE=DATE-TIME:20200616T234000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/7
DESCRIPTION:Title: Gravity from Averaging CFTs\nby Alex Maloney (McGill) as part of U
C Berkeley - BCTP string seminar\n\n\nAbstract\nI will explore the idea th
at certain theories of gravity in Anti-de\nSitter space are dual to an ave
rage over an ensemble of quantum\ntheories\, rather than to a specific qua
ntum theory. I will describe\nan average over Narain’s family of two-di
mensional 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 t
heory of\ngravity. But the gravitational theory looks more like a Chern-
Simons\ntheory than like Einstein gravity.\n
LOCATION:https://researchseminars.org/talk/BCTP_string/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jinzhao Wang (ETH Zurich)
DTSTART;VALUE=DATE-TIME:20200714T210000Z
DTEND;VALUE=DATE-TIME:20200714T220000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/8
DESCRIPTION:Title: Outer entropy = Bartnik-Bray inner mass\, and the gravitational ant co
njecture\nby Jinzhao Wang (ETH Zurich) as part of UC Berkeley - BCTP s
tring seminar\n\n\nAbstract\nEntropy and energy are found to be closely ti
ed on our quest for quantum gravity. We point out an interesting connectio
n between the recently proposed outer entropy\, a coarse-grained entropy d
efined for a compact spacetime domain motivated by the holographic duality
\, and the Bartnik-Bray quasilocal mass long known in the mathematics comm
unity. In both scenarios\, one seeks an optimal spacetime fill-in of a giv
en closed\, connected\, spacelike\, codimension-two boundary. We show that
for an outer-minimizing mean-convex surface\, the Bartnik-Bray inner mass
matches exactly with the irreducible mass corresponding to the outer entr
opy. The equivalence implies that the area laws derived from the outer ent
ropy are mathematically equivalent as the monotonicity property of the qua
silocal mass. It also gives rise to new bounds between entropy and the gra
vitational energy\, which naturally gives the gravitational counterpart to
Wall's ant conjecture. We also observe that the equality can be achieved
in a conformal flow of metrics\, which is structurally similar to the Ceyh
an-Faulkner proof of the ant conjecture. We compute the small sphere limit
of the outer entropy and it is proportional to the bulk stress tensor as
one would expect for a quasilocal mass.\n
LOCATION:https://researchseminars.org/talk/BCTP_string/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Geoff Penington
DTSTART;VALUE=DATE-TIME:20200728T224000Z
DTEND;VALUE=DATE-TIME:20200728T234000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/9
DESCRIPTION:Title: Leading order corrections to the quantum extremal surface prescription
\nby Geoff Penington as part of UC Berkeley - BCTP string seminar\n\n\
nAbstract\nThe QES prescription is a rule for computing entanglement entro
pies in quantum gravity that has become one of the central tools in hologr
aphy. In particular\, it was crucial to recent progress on understanding t
he Page curve for evaporating black holes. However\, as I will show\, a na
ïve application of the QES prescription for arbitrary bulk states is para
doxical\, even at leading order. Instead\, it needs to be replaced by a mo
re refined prescription based on tools from one-shot quantum Shannon theor
y. 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 order cor
rections.\n
LOCATION:https://researchseminars.org/talk/BCTP_string/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Graeme Stewart Baird Smith (Colorado)
DTSTART;VALUE=DATE-TIME:20200908T224000Z
DTEND;VALUE=DATE-TIME:20200908T234000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/10
DESCRIPTION:Title: Multipartite Optimized Correlation Measures and Holography\nby Gr
aeme Stewart Baird Smith (Colorado) as part of UC Berkeley - BCTP string s
eminar\n\n\nAbstract\nI’ll discuss ways to quantify multipartite correla
tions\, in quantum information and in holography. We’ll focus on optimiz
ed correlation measures: linear combinations of entropies minimized over a
ll possible purifications of a state that also satisfy monotonicity condit
ions. These contain far more information about correlations than entanglem
ent entropy alone. We give a procedure to derive such quantities\, and con
struct a menagerie of symmetric optimized correlation measures on three pa
rties. These include tripartite generalizations of the entanglement of pur
ification\, the squashed entanglement\, and the recently introduced Q-corr
elation and R-correlation. Some correlation measures vanish only on produc
t states\, and thus quantify both classical and quantum correlations\; oth
ers vanish on any separable state\, capturing quantum correlations alone.
We then use a procedure motivated by the surface-state correspondence to c
onstruct holographic duals for the correlation measures as linear combinat
ions of bulk surfaces. The geometry of the surfaces can preserve\, partial
ly break\, or fully break the symmetry of the correlation measure. The opt
imal purification is encoded in the locations of certain points\, whose lo
cations are fixed by constraints on the areas of combinations of surfaces.
This gives a new concrete connection between information theoretic quanti
ties evaluated on a boundary state and detailed geometric properties of it
s dual.\n
LOCATION:https://researchseminars.org/talk/BCTP_string/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Chitraang Murdia (UC Berkeley)
DTSTART;VALUE=DATE-TIME:20200915T224000Z
DTEND;VALUE=DATE-TIME:20200915T234000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/11
DESCRIPTION:Title: Coarse-Graining Holographic States and Semiclassical Bulk Flow\nb
y Chitraang Murdia (UC Berkeley) as part of UC Berkeley - BCTP string semi
nar\n\n\nAbstract\nI will describe a bulk procedure that generates a seque
nce of coarse-grained holographic states by disentangling degrees of freed
om at short distances. This is manifested as a flow in the bulk which appr
oaches quantum extremal surfaces. This procedure generalizes an earlier cl
assical construction by including bulk quantum corrections.\n
LOCATION:https://researchseminars.org/talk/BCTP_string/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Matthew Dodelson (IPMU)
DTSTART;VALUE=DATE-TIME:20200922T224000Z
DTEND;VALUE=DATE-TIME:20200922T234000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/12
DESCRIPTION:Title: Singularities of Thermal Correlators at Strong Coupling\nby Matth
ew Dodelson (IPMU) as part of UC Berkeley - BCTP string seminar\n\n\nAbstr
act\nI will describe work in progress with Ooguri on the singularities of
the two point function at finite temperature in a conformal field theory i
n more than two dimensions. At weak coupling the only singularity is on th
e light cone\, but in the large N\, large lambda regime a new singularity
emerges. This new singularity corresponds to a null geodesic in the AdS/Sc
hwarzschild black hole\, which may wrap the photon sphere many times. Afte
r deriving this result\, I will discuss the resolution of these singularit
ies by stringy tidal effects at finite lambda. The basic tool I will use i
s to take the Penrose limit around a given null geodesic\, and then use th
e solubility of the string theory in this background. I will also discuss
applications to rotating black holes.\n
LOCATION:https://researchseminars.org/talk/BCTP_string/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lampros Lamprou (MIT/UBC)
DTSTART;VALUE=DATE-TIME:20200929T224000Z
DTEND;VALUE=DATE-TIME:20200929T234000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/13
DESCRIPTION:Title: Inside the Hologram: The bulk observer's experience\nby Lampros L
amprou (MIT/UBC) as part of UC Berkeley - BCTP string seminar\n\nAbstract:
TBA\n
LOCATION:https://researchseminars.org/talk/BCTP_string/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Monica Kang (Caltech)
DTSTART;VALUE=DATE-TIME:20201006T224000Z
DTEND;VALUE=DATE-TIME:20201006T234000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/14
DESCRIPTION:Title: A GNS story of holographic baby universes\nby Monica Kang (Caltec
h) as part of UC Berkeley - BCTP string seminar\n\n\nAbstract\nI will intr
oduce a GNS construction as a formalism to study baby universes. This natu
rally shifts the primordial role to the algebra of observables rather than
the Hilbert spaces. I will explicitly form baby universe operations and u
tilize them to build baby universe algebras. Using these ingredients\, I w
ill construct the baby universe Hilbert spaces. I will highlight that this
approach will give an understanding of the miraculous cancellation as a n
atural result from the character theory. I will illustrate its physics by
giving two different physical settings as examples.\n
LOCATION:https://researchseminars.org/talk/BCTP_string/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Antony Speranza (Perimeter)
DTSTART;VALUE=DATE-TIME:20201013T224000Z
DTEND;VALUE=DATE-TIME:20201013T234000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/15
DESCRIPTION:Title: Anomalies in gravitational charge algebras of null boundaries and bla
ck hole entropy\nby Antony Speranza (Perimeter) as part of UC Berkeley
- BCTP string seminar\n\n\nAbstract\nI will discuss how the central charg
es appearing in near-horizon symmetry algebras arise from an anomalous tra
nsformation of the null boundary term in the gravitational action. This p
arallels the way in which the holographic Weyl anomaly appears in AdS/CFT\
, with the ambiguity in the normalization of the null generator being the
analogue of the choice of Weyl frame. As an application\, I will analyze
a generalization of the near-horizon Virasoro symmetries of Haco\, Hawking
\, Perry\, and Strominger\, and give a systematic derivation of the Wald-Z
oupas fluxes and central charges. In particular\, I will discuss a way to
define the quasilocal charges unambiguously\, and show that the central c
harge computed by the charge algebra is directly related to the horizon en
tropy via the Cardy formula.\n
LOCATION:https://researchseminars.org/talk/BCTP_string/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lorenz Eberhardt (IAS)
DTSTART;VALUE=DATE-TIME:20201026T173000Z
DTEND;VALUE=DATE-TIME:20201026T183000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/16
DESCRIPTION:Title: Partition functions of the tensionless string\nby Lorenz Eberhard
t (IAS) as part of UC Berkeley - BCTP string seminar\n\n\nAbstract\nI disc
uss string theory on AdS3xS3xT4 in the tensionless limit\, with one unit o
f NS-NS flux. This theory is conjectured to be dual to the symmetric produ
ct orbifold CFT. I show how to compute the full string partition function
on various locally AdS3 backgrounds\, such as thermal AdS3\, the BTZ black
and conical defects\, and find that it is independent of the actual backg
round\, but only depends on the boundary geometry. Consequently\, reproduc
ing the boundary partition function does not require a sum over bulk geome
tries\, but rather agrees with the string partition function on any bulk g
eometry with the appropriate boundary. I argue that the same mechanism sho
ws the factorization of the bulk partition function when geometries with d
isconnected boundaries are considered.\n
LOCATION:https://researchseminars.org/talk/BCTP_string/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jordan Cotler (Harvard)
DTSTART;VALUE=DATE-TIME:20201104T234000Z
DTEND;VALUE=DATE-TIME:20201105T004000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/17
DESCRIPTION:Title: Euclidean Wormholes and Gravitational Constrained Instantons\nby
Jordan Cotler (Harvard) as part of UC Berkeley - BCTP string seminar\n\n\n
Abstract\nWe discover a wide range of new nonperturbative effects in quant
um gravity\, namely moduli spaces of constrained saddles (often called con
strained instantons) of the Einstein-Hilbert action. We find these in all
spacetime dimensions\, for AdS and dS. Many can be written in closed for
m\, and some are shown to be quadratically stable. In the Euclidean AdS s
etting\, these constrained saddles correspond to Euclidean wormholes. In
3D AdS\, where the gravitational path integral is more tractable\, we stud
y these Euclidean wormholes and show that they encode the energy level sta
tistics of microstates of BTZ black holes. Furthermore\, these statistics
precisely agree with a quantitative prediction from random matrix theory.
\n
LOCATION:https://researchseminars.org/talk/BCTP_string/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Rob Myers (Perimeter Institute)
DTSTART;VALUE=DATE-TIME:20201201T234000Z
DTEND;VALUE=DATE-TIME:20201202T004000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/18
DESCRIPTION:Title: Quantum Extremal Islands Made Easy\nby Rob Myers (Perimeter Insti
tute) as part of UC Berkeley - BCTP string seminar\n\n\nAbstract\nWe illus
trate the appearance of quantum extremal islands in holographic setups in
higher dimensions. We emphasize the close parallel with the behaviour of h
olographic entanglement entropy in more familiar settings.\n
LOCATION:https://researchseminars.org/talk/BCTP_string/18/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mykhaylo Usatyuk (UC Berkeley)
DTSTART;VALUE=DATE-TIME:20201215T234000Z
DTEND;VALUE=DATE-TIME:20201216T004000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/19
DESCRIPTION:Title: Dilaton-gravity\, deformations of the minimal string\, and matrix mod
els\nby Mykhaylo Usatyuk (UC Berkeley) as part of UC Berkeley - BCTP s
tring seminar\n\n\nAbstract\nA large class of two-dimensional dilaton-grav
ity theories in asymptotically AdS2 spacetimes are holographically dual to
a matrix integral\, interpreted as an ensemble average over Hamiltonians.
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 dilaton po
tentials compared to previous work by including conical defects with small
deficit angles. In order to do this\, I show that these theories are equa
l to the large p limit of a natural deformation of the (2\, p) minimal str
ing theory.\n
LOCATION:https://researchseminars.org/talk/BCTP_string/19/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tom Rudelius (UC Berkeley)
DTSTART;VALUE=DATE-TIME:20210119T234000Z
DTEND;VALUE=DATE-TIME:20210120T004000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/20
DESCRIPTION:Title: Generalizations of Generalized Global Symmetries and the Swampland\nby Tom Rudelius (UC Berkeley) as part of UC Berkeley - BCTP string semi
nar\n\n\nAbstract\nStandard lore holds that a consistent theory of quantum
gravity cannot have exact global symmetries. In this talk\, we will show
how simple generalizations of this lore can be used to motivate a number o
f other well-supported "Swampland conjectures\," thereby highlighting the
importance of global symmetries for understanding universal features of qu
antum gravity.\n
LOCATION:https://researchseminars.org/talk/BCTP_string/20/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Zhenbin Yang (Stanford)
DTSTART;VALUE=DATE-TIME:20210202T234000Z
DTEND;VALUE=DATE-TIME:20210203T004000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/21
DESCRIPTION:Title: A violation of global symmetries from replica wormholes and the fate
of black hole remnants\nby Zhenbin Yang (Stanford) as part of UC Berke
ley - BCTP string seminar\n\n\nAbstract\nWe show that the presence of repl
ica wormholes in the Euclidean path integral of gravity leads to a non-per
turbative violation of any global symmetry present in the low-energy descr
iption of quantum gravity. Explicitly\, we compute the scattering probabil
ity between different charged states in several low-dimensional models of
quantum gravity and find a non-vanishing answer. This suggests that the se
t of all charged states is typically over-complete\, which has drastic con
sequences for the fate of black hole remnants that could carry a global sy
mmetry charge. In the holographic context\, we argue that the presence of
such a symmetry in the effective description of the bulk should appear on
the boundary as an emergent global symmetry after ensemble averaging.\n
LOCATION:https://researchseminars.org/talk/BCTP_string/21/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Joaquin Turiaci (UC Santa Barbara)
DTSTART;VALUE=DATE-TIME:20210209T234000Z
DTEND;VALUE=DATE-TIME:20210210T004000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/22
DESCRIPTION:Title: The black hole spectrum in (super)gravity\nby Joaquin Turiaci (UC
Santa Barbara) as part of UC Berkeley - BCTP string seminar\n\n\nAbstract
\nThe talk will focus on the spectrum of near-extremal black holes in grav
ity and near-BPS black holes in supergravity. For concreteness\, we will s
tudy cases in asymptotically four-dimensional flat space and three-dimensi
onal Anti-de Sitter. This will be done by analyzing quantum effects near t
he horizon captured by an emergent Jackiw-Teitelboim mode at low temperatu
res. This will allow us to systematically study questions such as the extr
emal degeneracy and the size of the gap in the black hole spectrum\, which
can be compared to some string theory constructions.\n
LOCATION:https://researchseminars.org/talk/BCTP_string/22/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Andreas Blommaert (Stanford)
DTSTART;VALUE=DATE-TIME:20210126T234000Z
DTEND;VALUE=DATE-TIME:20210127T004000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/23
DESCRIPTION:Title: Wormholes\, eigenbranes and ensembles\nby Andreas Blommaert (Stan
ford) as part of UC Berkeley - BCTP string seminar\n\n\nAbstract\nWe discu
ss the role of wormholes and eigenbranes in reconciling geometry with quan
tum mechanics\, working within two dimensional dilaton gravity. First\, we
review how wormholes enable geometry to accurate capture averaged propert
ies of late time correlators of chaotic quantum systems. Because these are
averaged properties\, naively\, wormholes in gravitational theories sugge
st some ensemble interpretation of those gravitational theories\, here emb
odied by some matrix integral. We then explain that the geometrical descri
ption of individual draws of this ensemble means considering the same grav
itational theory on specific background spacetime branes. These eigenbrane
s deform the gravity theory precisely like in open closed string duality a
nd collapse the ensemble to one quantum system.\n
LOCATION:https://researchseminars.org/talk/BCTP_string/23/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tadashi Takayanagi (YITP\, Kyoto)
DTSTART;VALUE=DATE-TIME:20210309T234000Z
DTEND;VALUE=DATE-TIME:20210310T004000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
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 string sem
inar\n\n\nAbstract\nPseudo-entropy is an interesting quantity with a simpl
e gravity dual\, \nwhich generalizes entanglement entropy such that it dep
ends on \nboth an initial and a final state. In this talk we start with an
\nintroduction of this new quantity explaining its basic properties.\nNex
t we will study its gravity dual. Finally\, we will present recent\nnumeri
cal 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 \nquantum orde
r parameter. This talk is based on \narXiv:2005.13801 and arXiv:2011.09648
.\n
LOCATION:https://researchseminars.org/talk/BCTP_string/25/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tom Hartman (Cornell)
DTSTART;VALUE=DATE-TIME:20210316T224000Z
DTEND;VALUE=DATE-TIME:20210316T234000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/26
DESCRIPTION:Title: Islands in Cosmology\nby Tom Hartman (Cornell) as part of UC Berk
eley - BCTP string seminar\n\n\nAbstract\nBlack hole interiors share some
features with cosmology: both have time dependence\, singularities\, horiz
ons\, and very large entropy density. In this talk I will discuss whether
recent progress on understanding the black hole interior and the Page curv
e\, based on quantum extremal islands\, gives new insight into quantum cos
mology.\n
LOCATION:https://researchseminars.org/talk/BCTP_string/26/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Netta Engelhardt (MIT)
DTSTART;VALUE=DATE-TIME:20210323T224000Z
DTEND;VALUE=DATE-TIME:20210323T234000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/27
DESCRIPTION:Title: Cosmic Censorship in AdS/CFT\nby Netta Engelhardt (MIT) as part o
f UC Berkeley - BCTP string seminar\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/BCTP_string/27/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alex May (UBC)
DTSTART;VALUE=DATE-TIME:20210504T224000Z
DTEND;VALUE=DATE-TIME:20210504T234000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/28
DESCRIPTION:Title: Quantum tasks require islands on the brane\nby Alex May (UBC) as
part of UC Berkeley - BCTP string seminar\n\n\nAbstract\nIn recent work\,
it was argued that quantum computations with inputs and outputs distribute
d in spacetime\, or quantum tasks\, impose constraints on entanglement in
holographic theories. The resulting constraint was named the connected wed
ge theorem and can be verified by a direct bulk proof using focusing argum
ents in general relativity. In this article we extend this work to the con
text of AdS/BCFT\, where an end-of-the-world brane is present in the bulk.
By considering quantum tasks which exploit information localized to the b
rane\, we find a new connected wedge theorem. We apply this theorem to bra
ne models of black holes\, where it relates the formation of islands in th
e Ryu-Takayanagi formula to causal features of the ambient spacetime. In p
articular\, we find that if the black hole interior is causally connected
to the radiation system through the ambient spacetime\, then an island for
ms. For constant tension branes in pure AdS the converse also holds.\n
LOCATION:https://researchseminars.org/talk/BCTP_string/28/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Henry Maxfield (UCSB)
DTSTART;VALUE=DATE-TIME:20210330T224000Z
DTEND;VALUE=DATE-TIME:20210330T234000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/29
DESCRIPTION:Title: Baby Universes and Worldline Field Theories\nby Henry Maxfield (U
CSB) as part of UC Berkeley - BCTP string seminar\n\n\nAbstract\nTopology
changing processes have played a central role in recent developments in qu
antum gravity\, and have been argued to lead to an abelian algebra of supe
rselected observables. I will discuss one-dimensional theories of quantum
gravity in this context. This invites comparison with a worldline formalis
m of QFT\, with its non-abelian algebra of quantum fields. This apparent t
ension is resolved by considering the different choices to be made when co
nstructing Hilbert spaces for quantum gravity and QFT.\n
LOCATION:https://researchseminars.org/talk/BCTP_string/29/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Petr Horava (UC Berkeley)
DTSTART;VALUE=DATE-TIME:20210420T224000Z
DTEND;VALUE=DATE-TIME:20210420T234000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/30
DESCRIPTION:Title: Large N Expansion and String Theory Out of Equilibrium\nby Petr H
orava (UC Berkeley) as part of UC Berkeley - BCTP string seminar\n\nAbstra
ct: TBA\n
LOCATION:https://researchseminars.org/talk/BCTP_string/30/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Simeon Hellerman (IPMU)
DTSTART;VALUE=DATE-TIME:20210406T224000Z
DTEND;VALUE=DATE-TIME:20210406T234000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/31
DESCRIPTION:Title: Quantum Information Theory of the Gravitational Anomaly\nby Simeo
n Hellerman (IPMU) as part of UC Berkeley - BCTP string seminar\n\n\nAbstr
act\nI will show that the notion of quantum entanglement is not\ndefined f
or gravitationally anomalous two-dimensional theories\,\nbecause they do n
ot admit a local tensor factorization of the Hilbert\nspace into local Hil
bert spaces. Qualitatively\, the modular flow\ncannot act consistently and
unitarily in a finite region\, if there are\ndifferent numbers of states
with a given energy traveling in the two\nopposite directions. I will make
this precise by decomposing it into\ntwo observations: First\, a two-dime
nsional conformal field theory\nadmits a consistent quantization on a spac
e with boundary only if it\nis not anomalous. Second\, a local tensor fact
orization always leads to\na definition of consistent\, unitary\, energy-p
reserving boundary\ncondition. As a corollary I will establish a generaliz
ation of the\nNielsen–Ninomiya theorem to all two-dimensional unitary lo
cal quantum\nfield theories: No continuum quantum field theory in two dime
nsions\ncan admit a lattice regulator unless its gravitational anomaly\nva
nishes. I will advocate that these points be used to reinterpret the\ngrav
itational anomaly quantum-information-theoretically\, as a\nfundamental ob
struction to the localization of quantum information.\n
LOCATION:https://researchseminars.org/talk/BCTP_string/31/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gary Horowitz (UCSB)
DTSTART;VALUE=DATE-TIME:20210413T224000Z
DTEND;VALUE=DATE-TIME:20210413T234000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/32
DESCRIPTION:Title: Boundary Causality Violating Metrics in Holography\nby Gary Horow
itz (UCSB) as part of UC Berkeley - BCTP string seminar\n\n\nAbstract\nThe
full bulk path integral in a Lorentzian formulation of holography include
s metrics that violate boundary causality. This leads to the following puz
zle: The commutator of two field theory operators at spacelike-separated p
oints on the boundary must vanish. However\, if these points are causally
related in a bulk metric\, then the bulk calculation of the commutator wil
l be nonzero. It would appear that the integral over all metrics of this c
ommutator must vanish exactly for holography to hold. This is puzzling sin
ce it must also be true if the commutator is multiplied by any other opera
tor. We give a prescription for the bulk path integral in which resolves t
his puzzle. In this approach\, the bulk dual of the boundary commutator is
not the limit of the naive bulk commutator.\n
LOCATION:https://researchseminars.org/talk/BCTP_string/32/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Herman Verlinde (Princeton)
DTSTART;VALUE=DATE-TIME:20210427T224000Z
DTEND;VALUE=DATE-TIME:20210427T234000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/33
DESCRIPTION:Title: Towards a string dual of SYK\nby Herman Verlinde (Princeton) as p
art of UC Berkeley - BCTP string seminar\n\n\nAbstract\nI present a propos
al for how the SYK model can be realized within string theory. Starting fr
om the matrix model description of the minimal string\, I show that the pa
rtition function on a configuration of Q FZZT branes takes the form of a m
atrix version of the SYK model. The SYK fermions arise from open strings
on brane intersections. I describe how time emerges upon taking the contin
uum limit and comment on the role of ensemble averaging in low dimensional
holography.\n
LOCATION:https://researchseminars.org/talk/BCTP_string/33/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ben Freivogel (University of Amsterdam)
DTSTART;VALUE=DATE-TIME:20210510T173000Z
DTEND;VALUE=DATE-TIME:20210510T183000Z
DTSTAMP;VALUE=DATE-TIME:20210514T204408Z
UID:BCTP_string/34
DESCRIPTION:Title: Wormholes calculate averages over states\nby Ben Freivogel (Unive
rsity of Amsterdam) as part of UC Berkeley - BCTP string seminar\n\n\nAbst
ract\nI will show that wormholes naturally arise as the gravity dual of an
average over different states within a single conformal field theory. The
se wormholes give a simple way to diagnose how typical pure states differ
from the thermal density matrix. Based on work to appear with D. Nikolakop
oulou and A. Rotundo.\n
LOCATION:https://researchseminars.org/talk/BCTP_string/34/
END:VEVENT
END:VCALENDAR