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BEGIN:VEVENT
SUMMARY:Netta Engelhardt (Massachusetts Institute of Technology)
DTSTART:20201207T150000Z
DTEND:20201207T160000Z
DTSTAMP:20260422T212829Z
UID:IASQubit2020/1
DESCRIPTION:Title: Free Energy from Replica Wormholes\nby Netta Engelhardt (Massachu
setts Institute of Technology) as part of Online Workshop on Qubits and Bl
ack Holes\n\n\nAbstract\nI will discuss progress towards understanding the
relationship between the gravitational path integral and the partition fu
nction via the gravitational free energy (more generally the generating fu
nctional). A proper computation of the free energy requires a replica tric
k distinct from the usual one used to compute the entropy. I will show tha
t in JT gravity there is a regime where the free energy computed without r
eplica wormholes is pathological. Interestingly\, the naive inclusion of r
eplica wormholes is not quite sufficient to resolve the pathology: an alte
rnative analytic continuation is required. I will discuss the implications
of this for various interpretations of the gravitational path integral (e
.g. as computing an ensemble average) and also mention some parallels with
spin glasses.\n
LOCATION:https://researchseminars.org/talk/IASQubit2020/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alex May (University of British Columbia)
DTSTART:20201207T160000Z
DTEND:20201207T170000Z
DTSTAMP:20260422T212829Z
UID:IASQubit2020/2
DESCRIPTION:Title: Quantum Tasks Require Islands on the Brane\nby Alex May (Universi
ty of British Columbia) as part of Online Workshop on Qubits and Black Hol
es\n\n\nAbstract\nIn recent work\, it was argued that quantum computations
with inputs and outputs distributed in spacetime\, or quantum tasks\, imp
ose constraints on entanglement in holographic theories. The resulting con
straint was named the connected wedge theorem and can verified by a direct
bulk proof using focusing arguments in general relativity. In this talk w
e extend this work to the context of AdS/BCFT\, where an end-of-the-world
brane is present in the bulk. By considering quantum tasks which exploit i
nformation localized to the brane\, we find a new connected wedge theorem.
We apply this theorem to brane models of black holes\, where it relates t
he formation of Islands in the Ryu-Takayanagi formula to causal features o
f the ambient spacetime. In particular we find that in simple models Islan
ds on the brane are causally connected to their corresponding radiation sy
stems.\n
LOCATION:https://researchseminars.org/talk/IASQubit2020/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mukund Rangamani (University of California\, Davis)
DTSTART:20201207T180000Z
DTEND:20201207T190000Z
DTSTAMP:20260422T212829Z
UID:IASQubit2020/3
DESCRIPTION:Title: Real-Time Gravitational Replicas\nby Mukund Rangamani (University
of California\, Davis) as part of Online Workshop on Qubits and Black Hol
es\n\n\nAbstract\nI will discuss real-time path integrals in gravitational
theories. As applications we will describe the general structure of repli
ca wormhole saddles and the effective dynamics of open quantum systems wit
h long-term memory.\n
LOCATION:https://researchseminars.org/talk/IASQubit2020/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Adam Bouland (University of California\, Berkeley)
DTSTART:20201207T190000Z
DTEND:20201207T200000Z
DTSTAMP:20260422T212829Z
UID:IASQubit2020/4
DESCRIPTION:Title: Pseudorandomness and the AdS/CFT Correspondence\nby Adam Bouland
(University of California\, Berkeley) as part of Online Workshop on Qubits
and Black Holes\n\n\nAbstract\nCould quantum circuit complexity have phys
ical ramifications? In the context of AdS/CFT\, Susskind has suggested tha
t it might\, as circuit complexity could be the CFT dual to AdS wormhole v
olume. Here we explore this proposal using cryptographic techniques. We fi
rst show how to create pseudorandom quantum states in the CFT\, thereby ar
guing that their quantum circuit complexity is not "feelable"\, in the sen
se that it cannot be approximated by any efficient experiment. By contrast
we argue that the wormhole volume is "feelable" in some general but non-p
hysical sense. The duality between a "feelable" quantity and an "unfeelabl
e" quantity implies that some aspect of this duality -- either the AdS/CFT
dictionary\, or else the dynamics of quantum gravity -- must have exponen
tial complexity. While at first sight this might seem to justify the disco
mfort of complexity theorists with equating complexity with a physical qua
ntity\, a further examination of our arguments shows that these conclusion
s are an inevitable consequence of the "wormhole growth paradox" which ins
pired this proposal in the first place. Based largely on https://arxiv.org
/abs/1910.14646\n
LOCATION:https://researchseminars.org/talk/IASQubit2020/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Thomas Mertens (Ghent University)
DTSTART:20201208T150000Z
DTEND:20201208T160000Z
DTSTAMP:20260422T212829Z
UID:IASQubit2020/5
DESCRIPTION:Title: Liouville and JT Quantum Gravity - Holography and Matrix Models\n
by Thomas Mertens (Ghent University) as part of Online Workshop on Qubits
and Black Holes\n\n\nAbstract\nI will discuss recent progress in understan
ding quantum gravity amplitudes (partition function\, boundary correlation
functions and multiboundary amplitudes) in Liouville gravity\, and how th
ey limit to Jackiw-Teitelboim (JT) amplitudes. I will provide two perspect
ives on the results: the Liouville gravity answers look like q-deformation
s of the JT answers\, and Liouville gravity can be related to a 2d dilaton
gravity with a sinh dilaton potential. Based largely on arXiv:2006.07072
and 2007.00998.\n
LOCATION:https://researchseminars.org/talk/IASQubit2020/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Javier Magan (Instituto Balseiro\, Centro Atómico de Bariloche)
DTSTART:20201208T160000Z
DTEND:20201208T170000Z
DTSTAMP:20260422T212829Z
UID:IASQubit2020/6
DESCRIPTION:Title: Entropic Order Parameters for the Phases of QFT\nby Javier Magan
(Instituto Balseiro\, Centro Atómico de Bariloche) as part of Online Work
shop on Qubits and Black Holes\n\n\nAbstract\nWe start by describing how g
eneralized symmetries in QFT arise in the violation of elementary properti
es that appear when we associate algebras to regions in QFT. This observat
ion provides a new perspective/proof of the abelian nature of generalized
symmetries. Further\, the algebra of order/disorder parameters is fixed an
d can be deduced without the explicit construction of the non-local operat
ors. In these scenarios\, there are two natural algebras associated with r
egions of specific topologies\, suggesting a simple geometrical order para
meter defined as a relative entropy. These relative entropies satisfy a
“certainty relation” connecting the statistics of the order and disord
er parameters. We describe old and new aspects of the phases of QFT’s wi
th generalized symmetries from this perspective. In particular\, the certa
inty relation makes transparent the duality between constant and area law
behaviors in symmetry-breaking scenarios\, and in CFT’s there are relati
ve entropies exactly computable.\n
LOCATION:https://researchseminars.org/talk/IASQubit2020/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Monika Schleier-Smith (Stanford University)
DTSTART:20201208T180000Z
DTEND:20201208T190000Z
DTSTAMP:20260422T212829Z
UID:IASQubit2020/7
DESCRIPTION:Title: Programmable Non-Local Interactions: Towards Fast Scrambling with Col
d Atoms\nby Monika Schleier-Smith (Stanford University) as part of Onl
ine Workshop on Qubits and Black Holes\n\n\nAbstract\nThe quest to build a
nd probe toy models of quantum gravity in table-top experiments presents a
new frontier for the field of quantum simulation. One challenge is to sim
ulate fast scrambling of quantum information in black holes\, for which a
key requirement is to engineer a quantum system with a non-local graph of
interactions. I will report on advances in control of non-local interactio
ns in experiments with cold atoms. By coupling the atoms to light in an op
tical resonator\, we generate tunable non-local Heisenberg interactions\,
which we characterize by imaging the resulting phases and dynamics. Notabl
e observations include interaction-based protection of spin coherence and
photon-mediated spin-mixing\, a mechanism for generating correlated atom p
airs. I will present recent results on optically programming the distance-
dependence of the spin-spin couplings\, with prospects for studying fast s
crambling and for accessing treelike (p-adic) geometries akin to hyperboli
c space.\n
LOCATION:https://researchseminars.org/talk/IASQubit2020/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Douglas Stanford (Stanford University)
DTSTART:20201208T190000Z
DTEND:20201208T200000Z
DTSTAMP:20260422T212829Z
UID:IASQubit2020/8
DESCRIPTION:Title: Comments about Wormholes and Quantum Noise\nby Douglas Stanford (
Stanford University) as part of Online Workshop on Qubits and Black Holes\
n\n\nAbstract\nWe will comment on wormholes for the off-diagonal component
s of the density matrix of Hawking radiation. Then we will discuss work in
progress on a simple model in which small effects associated with unitari
ty of time evolution may be related to further topologies.\n
LOCATION:https://researchseminars.org/talk/IASQubit2020/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Edward Witten (Institute for Advanced Study)
DTSTART:20201209T150000Z
DTEND:20201209T160000Z
DTSTAMP:20260422T212829Z
UID:IASQubit2020/9
DESCRIPTION:Title: Some Comments on Energy Inequalities\nby Edward Witten (Institute
for Advanced Study) as part of Online Workshop on Qubits and Black Holes\
n\n\nAbstract\nThe talk will consist of some general observations about en
ergy inequalities\, such as the statement that the energy density averaged
over a time-like curve is bounded below and the statement that the averag
ed null energy on a null geodesic in Minkowski space is nonnegative.\n
LOCATION:https://researchseminars.org/talk/IASQubit2020/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lampros Lamprou (Massachusetts Institute of Technology)
DTSTART:20201209T160000Z
DTEND:20201209T170000Z
DTSTAMP:20260422T212829Z
UID:IASQubit2020/10
DESCRIPTION:Title: Inside the Hologram: The Bulk Observer's Experience\nby Lampros
Lamprou (Massachusetts Institute of Technology) as part of Online Workshop
on Qubits and Black Holes\n\n\nAbstract\nI will present a holographic fra
mework for reconstructing the experience of bulk observers in AdS/CFT. In
particular\, I will show how to recover the proper time and energy distrib
ution measured along bulk worldlines\, directly in the CFT via a universal
\, background-independent prescription. For an observer falling into an et
ernal AdS black hole\, the proposal resolves a conceptual puzzle raised by
Marolf and Wall. It suffers\, however\, from the "frozen vacuum" problem
for which I will offer some preliminary comments. Notably\, the approach d
oes not depend crucially on the asymptotic Hamiltonian and it outlines a g
eneral framework for the emergence of time.\n
LOCATION:https://researchseminars.org/talk/IASQubit2020/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Chris Akers (Massachusetts Institute of Technology)
DTSTART:20201209T180000Z
DTEND:20201209T190000Z
DTSTAMP:20260422T212829Z
UID:IASQubit2020/11
DESCRIPTION:Title: Quantum Minimal Surfaces in Quantum Error-Correction\nby Chris A
kers (Massachusetts Institute of Technology) as part of Online Workshop on
Qubits and Black Holes\n\n\nAbstract\nWhat is the role of quantum extrema
l surfaces (QES) in general quantum error-correcting codes? I will present
preliminary results starting to answer this question\, expanding on the p
revious work of Harlow\, providing necessary and sufficient conditions for
a general code to satisfy a quantum minimal surface prescription.\n
LOCATION:https://researchseminars.org/talk/IASQubit2020/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Geoffrey Penington (University of California\, Berkeley)
DTSTART:20201209T190000Z
DTEND:20201209T200000Z
DTSTAMP:20260422T212829Z
UID:IASQubit2020/12
DESCRIPTION:Title: Life without Pythons would be so Simple\nby Geoffrey Penington (
University of California\, Berkeley) as part of Online Workshop on Qubits
and Black Holes\n\n\nAbstract\nReconstruction of bulk operators within the
causal wedge is simple to achieve using Lorentzian causal bulk dynamics.
In contrast\, the only known methods for reconstructing arbitrary operator
s in the full entanglement wedge (the Petz map\, modular flow etc.) are hi
ghly complex from a boundary perspective. It was previously argued based o
n intuition from tensor networks that this complexity is necessary if the
bulk operator hidden behind an extremal surface (in a ‘python’s lunch
’). However in general there may be operators which are not in a lunch\,
but are also not in the causal wedge. I will argue that such operators ca
n also be simply\, and causally\, reconstructed by gradually expanding the
causal wedge using time folds with different boundary conditions.\n
LOCATION:https://researchseminars.org/talk/IASQubit2020/12/
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