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BEGIN:VEVENT
SUMMARY:Ling-Yan (Janet) Hung (Fudan University)
DTSTART:20211206T140000Z
DTEND:20211206T144500Z
DTSTAMP:20260422T212830Z
UID:IASQubit2021/1
DESCRIPTION:Title: Bending the Padic Tensor Network and Emergent Einstein Equation\n
by Ling-Yan (Janet) Hung (Fudan University) as part of Workshop on Quantum
Information and Spacetime\n\nLecture held in Wolfensohn Hall.\n\nAbstract
\nWe take the tensor network describing explicit p-adic CFT partition func
tions proposed in 1902.01411\, and consider boundary conditions of the net
work describing a deformed Bruhat-Tits (BT) tree geometry. We demonstrate
that this geometry satisfies an emergent graph Einstein equation in a uniq
ue way that is consistent with the bulk effective matter action encoding t
he same correlation function as the tensor network\, at least in the pertu
rbative limit order by order away from the pure BT tree. Moreover\, the (p
erturbative) definition of the graph curvature in the Mathematics literatu
re naturally emerges from the consistency requirements of the emergent Ein
stein equation. The emergent "metric" in the tenor network can be interpre
ted as a Fisher information between states.\n
LOCATION:https://researchseminars.org/talk/IASQubit2021/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jordan Cotler (Harvard University)
DTSTART:20211206T144500Z
DTEND:20211206T153000Z
DTSTAMP:20260422T212830Z
UID:IASQubit2021/2
DESCRIPTION:Title: Quantum Complexity of Experiments\nby Jordan Cotler (Harvard Univ
ersity) as part of Workshop on Quantum Information and Spacetime\n\nLectur
e held in Wolfensohn Hall.\n\nAbstract\nWe introduce a theoretical framewo
rk to study experimental physics using quantum complexity theory. This all
ows us to address: what is the computational complexity of an experiment?
For several 'model' experiments\, we prove that there is an exponential sa
vings in resources if the experimentalist can entangle apparatuses with ex
perimental samples. A novel example is the experimental task of determinin
g the symmetry class of a time evolution operator for a quantum many-body
system. Some of our complexity advantages have been realized on Google's S
ycamore processor\, demonstrating a real-world advantage for learning algo
rithms with a quantum memory.\n
LOCATION:https://researchseminars.org/talk/IASQubit2021/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nicole Yunger Halpern (NIST & University of Maryland)
DTSTART:20211206T161500Z
DTEND:20211206T170000Z
DTSTAMP:20260422T212830Z
UID:IASQubit2021/3
DESCRIPTION:Title: Proofs of Two Brown-and-Susskind Complexity Conjectures\nby Nicol
e Yunger Halpern (NIST & University of Maryland) as part of Workshop on Qu
antum Information and Spacetime\n\nLecture held in Wolfensohn Hall.\n\nAbs
tract\nIn 2017\, Adam Brown and Lenny Susskind posed two conjectures about
quantum complexity\, the difficulty of preparing a desired many-body stat
e from a simple tensor product: (1) Under chaotic evolutions\, complexity
grows linearly for a time exponential in the system size. (2) A resource t
heory for uncomplexity can be defined. (Resource theories are simple model
s\, developed in quantum information theory\, for situations in which cons
traints restrict the operations one can perform. Uncomplexity is a lack of
complexity\, useful in inputs to quantum computations.) We prove both con
jectures correct\, using tools from quantum information theory\, algebraic
geometry\, and differential topology.\nReferences:\n1) Haferkamp\, Faist\
, Kothakonda\, Eisert\, and NYH\, arXiv:2106.05305 (2021).\n2) NYH\, Kotha
konda\, Haferkamp\, Munson\, Faist\, and Eisert\, arXiv:2110.11371 (2021).
\n
LOCATION:https://researchseminars.org/talk/IASQubit2021/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Andru Gheorghiu (ETH Zurich)
DTSTART:20211206T170000Z
DTEND:20211206T174500Z
DTSTAMP:20260422T212830Z
UID:IASQubit2021/4
DESCRIPTION:Title: On Estimating the Entropy of Shallow Circuit Outputs\nby Andru Gh
eorghiu (ETH Zurich) as part of Workshop on Quantum Information and Spacet
ime\n\nLecture held in Wolfensohn Hall.\n\nAbstract\nComputing the entropy
of probability distributions and quantum states is a fundamental task in
information processing. In this talk I'll discuss recent work with Matty H
oban (arXiv:2002.12814) in which we show that estimating the entropy of qu
antum states (or probability distributions) produced by shallow quantum ci
rcuits is at least as hard as the Learning-With-Errors problem\, and thus
believed to be intractable for efficient quantum computation. This shows t
hat circuits do not need to be complex to render the computation of entrop
y a difficult task. We also give complexity-theoretic evidence that the pr
oblem is not as hard as its counterpart with general polynomial-size circu
its\, seemingly occupying an intermediate hardness regime. As a potential
application to quantum gravity research\, we relate these results to the c
omplexity of the bulk-to-boundary dictionary of AdS/CFT.\n
LOCATION:https://researchseminars.org/talk/IASQubit2021/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:ChunJun (Charles) Cao (University of Maryland)
DTSTART:20211206T194500Z
DTEND:20211206T203000Z
DTSTAMP:20260422T212830Z
UID:IASQubit2021/5
DESCRIPTION:Title: Tensor Network and Approximate Holographic Codes\nby ChunJun (Cha
rles) Cao (University of Maryland) as part of Workshop on Quantum Informat
ion and Spacetime\n\nLecture held in Wolfensohn Hall.\n\nAbstract\nAlthoug
h it is known that AdS/CFT as a quantum erasure correction code is only ap
proximate\, there is still much to learn about the precise bulk physical c
onsequences of deviating from exact erasure correction codes. In this talk
\, I will take initial steps in addressing this gap of knowledge and discu
ss an intuitive tensor network model that corresponds to a tunable class o
f approximate holographic codes. We find that features analogous to gravit
y can emerge when "quantum noise" is injected into such holographic stabil
izer codes.\n
LOCATION:https://researchseminars.org/talk/IASQubit2021/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Juan Pedraza (University of Barcelona)
DTSTART:20211206T213000Z
DTEND:20211206T221500Z
DTSTAMP:20260422T212830Z
UID:IASQubit2021/6
DESCRIPTION:Title: Lorentzian Threads and Holographic Complexity\nby Juan Pedraza (U
niversity of Barcelona) as part of Workshop on Quantum Information and Spa
cetime\n\nLecture held in Wolfensohn Hall.\n\nAbstract\nThe continuous min
flow-max cut principle is used to reformulate the 'complexity=volume' con
jecture using Lorentzian flows. Conceptually\, discretized flows are inter
preted in terms of `gatelines'\, one-dimensional time-like curves that con
nect layers of a tensor network grid in the bulk spacetime. We imagine eac
h gateline represents a unitary operation such that the bulk calculation f
or complexity matches its information-theoretic definition. The bulk sympl
ectic potential provides a 'canonical' flow configuration characterizing p
erturbations around arbitrary CFT states. Its consistency requires the bul
k to obey linearized Einstein's equations\, which are shown to be equivale
nt to the holographic first law of complexity\, thereby advocating a notio
n of 'spacetime complexity'. Finally\, we explain the need for a more gene
ral measure of complexity that captures the role of suboptimal flows or te
nsor network configurations. Based on 2105.12735 and 2106.12585.\n
LOCATION:https://researchseminars.org/talk/IASQubit2021/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Felix M. Haehl (Institute for Advanced Study)
DTSTART:20211206T221500Z
DTEND:20211206T230000Z
DTSTAMP:20260422T212830Z
UID:IASQubit2021/7
DESCRIPTION:Title: Spin Glasses and Holography\nby Felix M. Haehl (Institute for Adv
anced Study) as part of Workshop on Quantum Information and Spacetime\n\nL
ecture held in Wolfensohn Hall.\n\nAbstract\nThe connections between disor
dered quantum systems (specifically the SYK model)\, ensemble averaging\,
and two-dimensional dilaton gravity underlie much of the recent progress o
n holography and quantum gravity. I will discuss simple disordered systems
\, which exhibit spin glass order and allow for an analytical treatment in
certain limits. I will focus on some of their properties that are of inte
rest from a gravitational point of view (such as thermodynamics and quantu
m chaos) and propose a holographic interpretation.\n
LOCATION:https://researchseminars.org/talk/IASQubit2021/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tatsuma Nishioka (Yukawa Institute for Theoretical Physics\, Kyoto
University)
DTSTART:20211207T140000Z
DTEND:20211207T144500Z
DTSTAMP:20260422T212830Z
UID:IASQubit2021/8
DESCRIPTION:Title: Topological Pseudo Entropy\nby Tatsuma Nishioka (Yukawa Institute
for Theoretical Physics\, Kyoto University) as part of Workshop on Quantu
m Information and Spacetime\n\nLecture held in Wolfensohn Hall.\n\nAbstrac
t\nRecently\, a new quantum information measure called pseudo entropy was
introduced as a generalization of entanglement entropy to quantify quantum
correlation between initial and final states in a time-dependent system.
In this talk\, I will examine some aspects of pseudo entropy in topologica
l field theory and conformal field theory (CFT). In three-dimensional Cher
n-Simons theory\, pseudo entropy can be given by a partition function on a
three-sphere with Wilson loops in a similar manner to topological entangl
ement entropy. I will also show that the pseudo entropy in a certain setup
is equivalent to the interface entropy in two-dimensional CFTs\, and leve
rage the equivalence to calculate the pseudo entropies in particular examp
les. Furthermore\, I will define a pseudo entropy extension of the left-ri
ght entanglement entropy in two-dimensional boundary CFTs and derive a uni
versal formula for a pair of arbitrary boundary states.\n
LOCATION:https://researchseminars.org/talk/IASQubit2021/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Pengfei Zhang (Caltech)
DTSTART:20211207T144500Z
DTEND:20211207T153000Z
DTSTAMP:20260422T212830Z
UID:IASQubit2021/9
DESCRIPTION:Title: Branching Time in SYK-like Models\nby Pengfei Zhang (Caltech) as
part of Workshop on Quantum Information and Spacetime\n\nLecture held in W
olfensohn Hall.\n\nAbstract\nThe branching time in SYK-like models is defi
ned as the average time separation of rungs when computing the out-of-time
-order correlator. We argue that a parametrically large branching time is
necessary to obtain holographic models with non-trivial bulk dynamics. In
this work\, we establish a bound on the branching time for SYK-like models
. Thus\, such models are unlikely candidates for sub-AdS holography. We al
so derive a relation between the branching time\, the Lyapunov exponent\,
and the quasiparticle lifetime in the weak coupling limit.\n
LOCATION:https://researchseminars.org/talk/IASQubit2021/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ying Zhao (University of California\, Santa Barbara)
DTSTART:20211207T161500Z
DTEND:20211207T170000Z
DTSTAMP:20260422T212830Z
UID:IASQubit2021/10
DESCRIPTION:Title: Quantum Circuit and Collisions in the Black Hole Interior\nby Yi
ng Zhao (University of California\, Santa Barbara) as part of Workshop on
Quantum Information and Spacetime\n\nLecture held in Wolfensohn Hall.\nAbs
tract: TBA\n
LOCATION:https://researchseminars.org/talk/IASQubit2021/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Shaokai Jian (Brandeis University)
DTSTART:20211207T170000Z
DTEND:20211207T174500Z
DTSTAMP:20260422T212830Z
UID:IASQubit2021/11
DESCRIPTION:Title: Late Time von Neumann Entropy and Measurement-induced Phase Transiti
on\nby Shaokai Jian (Brandeis University) as part of Workshop on Quant
um Information and Spacetime\n\nLecture held in Wolfensohn Hall.\n\nAbstra
ct\nWe present our studies on the late-time von Neumann entropy and its tr
ansition in Brownian SYK models. Without measurement\, we show that the co
rrelations between different replicas account for the Page curve at late t
ime\, and a permutation group structure emerges in the calculation. In the
presence of measurements\, we show that a continuous von Neumann entropy
transition from volume-law to area-law occurs at the point of replica symm
etry breaking.\n
LOCATION:https://researchseminars.org/talk/IASQubit2021/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Phil Saad (Institute for Advanced Study)
DTSTART:20211207T194500Z
DTEND:20211207T203000Z
DTSTAMP:20260422T212830Z
UID:IASQubit2021/12
DESCRIPTION:Title: Comments on Wormholes and Factorization\nby Phil Saad (Institute
for Advanced Study) as part of Workshop on Quantum Information and Spacet
ime\n\nLecture held in Wolfensohn Hall.\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/IASQubit2021/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jorrit Kruthoff (Stanford University)
DTSTART:20211207T213000Z
DTEND:20211207T221500Z
DTSTAMP:20260422T212830Z
UID:IASQubit2021/13
DESCRIPTION:Title: Gravity Factorized\nby Jorrit Kruthoff (Stanford University) as
part of Workshop on Quantum Information and Spacetime\n\nLecture held in W
olfensohn Hall.\n\nAbstract\nIn this talk I will discuss models of two-dim
ensional gravity that resolve the factorization puzzle and have a discrete
spectrum\, whilst retaining a semiclassical description. A novelty of the
se models is that they contain non-trivially correlated spacetime branes o
r\, equivalently\, nonlocal interactions in their action. Demanding factor
ization fixes almost all brane correlators\, and the exact geometric expan
sion of the partition function collapses to only two terms: the black hole
saddle and a subleading "half-wormhole" geometry\, whose sum yields the d
esired discrete spectrum. Non-perturbatively\, the correlated branes are a
certain multitrace interaction and I will show how it results in a factor
izing theory with discrete spectrum. I will end with a few comments on the
relevance of wormholes and higher dimensions.\n
LOCATION:https://researchseminars.org/talk/IASQubit2021/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Luca Iliesiu (Stanford University)
DTSTART:20211207T221500Z
DTEND:20211207T230000Z
DTSTAMP:20260422T212830Z
UID:IASQubit2021/14
DESCRIPTION:Title: The Volume of the Black Hole Interior at Late Times\nby Luca Ili
esiu (Stanford University) as part of Workshop on Quantum Information and
Spacetime\n\nLecture held in Wolfensohn Hall.\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/IASQubit2021/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Suvrat Raju (International Centre for Theoretical Sciences\, Benga
luru)
DTSTART:20211208T140000Z
DTEND:20211208T144500Z
DTSTAMP:20260422T212830Z
UID:IASQubit2021/15
DESCRIPTION:Title: Failure of the Split Property in Gravity and the Information Paradox
\nby Suvrat Raju (International Centre for Theoretical Sciences\, Beng
aluru) as part of Workshop on Quantum Information and Spacetime\n\nLecture
held in Wolfensohn Hall.\n\nAbstract\nIn an ordinary quantum field theory
\, the "split property" implies that the state of a system can be specifie
d independently on a bounded subregion of a Cauchy slice and its complemen
t. This property does not hold for theories of gravity. It can be shown in
specific examples that observables near the boundary of a Cauchy slice un
iquely fix the state on the entire slice. The original formulation of the
information paradox explicitly assumed the split property and we follow th
is assumption to isolate the precise error in Hawking's argument. A simila
r assumption also underpins the monogamy paradox of Mathur and AMPS. Final
ly the same assumption is used to support the common idea that the entangl
ement entropy of the region outside a black hole should follow a Page curv
e. It is for this reason that recent computations of the Page curve have b
een performed only in nonstandard theories of gravity\, which include a no
ngravitational bath and massive gravitons. We discuss possibilities for co
arse graining that might lead to a Page curve in standard theories of grav
ity.\n
LOCATION:https://researchseminars.org/talk/IASQubit2021/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Thomas Hertog (Katholieke Universiteit\, Leuven)
DTSTART:20211208T144500Z
DTEND:20211208T153000Z
DTSTAMP:20260422T212830Z
UID:IASQubit2021/16
DESCRIPTION:Title: A Page-like Transition in Quantum Cosmology\nby Thomas Hertog (K
atholieke Universiteit\, Leuven) as part of Workshop on Quantum Informatio
n and Spacetime\n\nLecture held in Wolfensohn Hall.\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/IASQubit2021/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Arvin Shahbazi-Moghaddam (Stanford University)
DTSTART:20211208T161500Z
DTEND:20211208T170000Z
DTSTAMP:20260422T212830Z
UID:IASQubit2021/17
DESCRIPTION:Title: Island Finder and Singularity Theorem\nby Arvin Shahbazi-Moghadd
am (Stanford University) as part of Workshop on Quantum Information and Sp
acetime\n\nLecture held in Wolfensohn Hall.\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/IASQubit2021/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Adam Levine (Institute for Advanced Study)
DTSTART:20211208T170000Z
DTEND:20211208T174500Z
DTSTAMP:20260422T212830Z
UID:IASQubit2021/18
DESCRIPTION:Title: Scattering Strings Off Quantum Extremal Surfaces\nby Adam Levine
(Institute for Advanced Study) as part of Workshop on Quantum Information
and Spacetime\n\nLecture held in Wolfensohn Hall.\n\nAbstract\nI will dis
cuss recent work on a Hayden & Preskill like setup for both maximally chao
tic and sub- maximally chaotic quantum field theories. I will discuss comp
utations of various quantum information measures on the boundary that tell
us when a particle has left the entanglement wedge of a given region. In
a maximally chaotic theory\, these measures indicate a sharp transition wh
ere the particle enters the wedge exactly when the insertion is null separ
ated from the quantum extremal surface for r. For sub-maximally chaotic th
eories\, we find a smoothed crossover at a delayed time given in terms of
the smaller Lyapunov exponent and dependent on the time-smearing scale of
the probe excitation. I will speculate on the extent to which our results
reveal properties of the target of the probe excitation as a “stringy qu
antum extremal surface” or simply quantify the probe itself thus giving
a new approach to studying the notion of longitudinal string spreading.\n
LOCATION:https://researchseminars.org/talk/IASQubit2021/18/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Geoffrey Pennington (University of California\, Berkeley & Institu
te for Advanced Study)
DTSTART:20211208T190000Z
DTEND:20211208T194500Z
DTSTAMP:20260422T212830Z
UID:IASQubit2021/19
DESCRIPTION:Title: One-Shot Holography\nby Geoffrey Pennington (University of Calif
ornia\, Berkeley & Institute for Advanced Study) as part of Workshop on Qu
antum Information and Spacetime\n\nLecture held in Wolfensohn Hall.\nAbstr
act: TBA\n
LOCATION:https://researchseminars.org/talk/IASQubit2021/19/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alexey Milekhin (University of California\, Santa Barbara)
DTSTART:20211208T194500Z
DTEND:20211208T203000Z
DTSTAMP:20260422T212830Z
UID:IASQubit2021/20
DESCRIPTION:Title: Charge Fluctuation Entropy of Hawking Radiation: A Replica-free Way
to Find Large Entropy\nby Alexey Milekhin (University of California\,
Santa Barbara) as part of Workshop on Quantum Information and Spacetime\n\
nLecture held in Wolfensohn Hall.\n\nAbstract\nWe study the fluctuation en
tropy for two-dimensional matter systems with an internal symmetry coupled
to Jackiw--Teitelboim(JT) gravity joined to a Minkowski region. The fluct
uation entropy is the Shannon entropy associated with probabilities of fin
ding a particular charge in a region. We first consider a case where the m
atter has a global symmetry. We find that the fluctuation entropy of Hawki
ng radiation shows an unbounded growth and exceeds the entanglement entrop
y in the presence of islands. This indicates that the global symmetry is v
iolated. We then discuss the fluctuation entropy for matter coupled to a t
wo-dimensional gauge field. We find a lower bound on the gauge coupling g_
0 in order to avoid a similar issue. Also\, we point out a few puzzles rel
ated to the island prescription in presence of a gauge symmetry.\nBased on
: https://arxiv.org/abs/2109.03841 in collaboration with Amirhossein Tajdi
ni\n
LOCATION:https://researchseminars.org/talk/IASQubit2021/20/
END:VEVENT
END:VCALENDAR