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BEGIN:VEVENT
SUMMARY:Ling-Yan (Janet) Hung (Fudan University)
DTSTART:20211206T140000Z
DTEND:20211206T144500Z
DTSTAMP:20260404T094338Z
UID:IASQubit2021/1
DESCRIPTION:Title: Bending the Padic Tensor Network and Emergent Einstein Equatio
n\nby Ling-Yan (Janet) Hung (Fudan University) as part of Workshop on
Quantum Information and Spacetime\n\nLecture held in Wolfensohn Hall.\n\nA
bstract\nWe take the tensor network describing explicit p-adic CFT partiti
on functions proposed in 1902.01411\, and consider boundary conditions of
the network describing a deformed Bruhat-Tits (BT) tree geometry. We demon
strate that this geometry satisfies an emergent graph Einstein equation in
a unique way that is consistent with the bulk effective matter action enc
oding the same correlation function as the tensor network\, at least in th
e perturbative limit order by order away from the pure BT tree. Moreover\,
the (perturbative) definition of the graph curvature in the Mathematics l
iterature naturally emerges from the consistency requirements of the emerg
ent Einstein equation. The emergent "metric" in the tenor network can be i
nterpreted as a Fisher information between states.\n
LOCATION:https://stable.researchseminars.org/talk/IASQubit2021/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jordan Cotler (Harvard University)
DTSTART:20211206T144500Z
DTEND:20211206T153000Z
DTSTAMP:20260404T094338Z
UID:IASQubit2021/2
DESCRIPTION:Title: Quantum Complexity of Experiments\nby Jordan Cotler (Harva
rd University) as part of Workshop on Quantum Information and Spacetime\n\
nLecture held in Wolfensohn Hall.\n\nAbstract\nWe introduce a theoretical
framework to study experimental physics using quantum complexity theory. T
his allows us to address: what is the computational complexity of an exper
iment? For several 'model' experiments\, we prove that there is an exponen
tial savings in resources if the experimentalist can entangle apparatuses
with experimental samples. A novel example is the experimental task of det
ermining the symmetry class of a time evolution operator for a quantum man
y-body system. Some of our complexity advantages have been realized on Goo
gle's Sycamore processor\, demonstrating a real-world advantage for learni
ng algorithms with a quantum memory.\n
LOCATION:https://stable.researchseminars.org/talk/IASQubit2021/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nicole Yunger Halpern (NIST & University of Maryland)
DTSTART:20211206T161500Z
DTEND:20211206T170000Z
DTSTAMP:20260404T094338Z
UID:IASQubit2021/3
DESCRIPTION:Title: Proofs of Two Brown-and-Susskind Complexity Conjectures\nb
y Nicole Yunger Halpern (NIST & University of Maryland) as part of Worksho
p on Quantum Information and Spacetime\n\nLecture held in Wolfensohn Hall.
\n\nAbstract\nIn 2017\, Adam Brown and Lenny Susskind posed two conjecture
s about quantum complexity\, the difficulty of preparing a desired many-bo
dy state from a simple tensor product: (1) Under chaotic evolutions\, comp
lexity grows linearly for a time exponential in the system size. (2) A res
ource theory for uncomplexity can be defined. (Resource theories are simpl
e models\, developed in quantum information theory\, for situations in whi
ch constraints restrict the operations one can perform. Uncomplexity is a
lack of complexity\, useful in inputs to quantum computations.) We prove b
oth conjectures correct\, using tools from quantum information theory\, al
gebraic geometry\, and differential topology.\nReferences:\n1) Haferkamp\,
Faist\, Kothakonda\, Eisert\, and NYH\, arXiv:2106.05305 (2021).\n2) NYH\
, Kothakonda\, Haferkamp\, Munson\, Faist\, and Eisert\, arXiv:2110.11371
(2021).\n
LOCATION:https://stable.researchseminars.org/talk/IASQubit2021/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Andru Gheorghiu (ETH Zurich)
DTSTART:20211206T170000Z
DTEND:20211206T174500Z
DTSTAMP:20260404T094338Z
UID:IASQubit2021/4
DESCRIPTION:Title: On Estimating the Entropy of Shallow Circuit Outputs\nby A
ndru Gheorghiu (ETH Zurich) as part of Workshop on Quantum Information and
Spacetime\n\nLecture held in Wolfensohn Hall.\n\nAbstract\nComputing the
entropy of probability distributions and quantum states is a fundamental t
ask in information processing. In this talk I'll discuss recent work with
Matty Hoban (arXiv:2002.12814) in which we show that estimating the entrop
y of quantum states (or probability distributions) produced by shallow qua
ntum circuits is at least as hard as the Learning-With-Errors problem\, an
d thus believed to be intractable for efficient quantum computation. This
shows that circuits do not need to be complex to render the computation of
entropy a difficult task. We also give complexity-theoretic evidence that
the problem is not as hard as its counterpart with general polynomial-siz
e circuits\, seemingly occupying an intermediate hardness regime. As a pot
ential application to quantum gravity research\, we relate these results t
o the complexity of the bulk-to-boundary dictionary of AdS/CFT.\n
LOCATION:https://stable.researchseminars.org/talk/IASQubit2021/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:ChunJun (Charles) Cao (University of Maryland)
DTSTART:20211206T194500Z
DTEND:20211206T203000Z
DTSTAMP:20260404T094338Z
UID:IASQubit2021/5
DESCRIPTION:Title: Tensor Network and Approximate Holographic Codes\nby ChunJ
un (Charles) Cao (University of Maryland) as part of Workshop on Quantum I
nformation and Spacetime\n\nLecture held in Wolfensohn Hall.\n\nAbstract\n
Although it is known that AdS/CFT as a quantum erasure correction code is
only approximate\, there is still much to learn about the precise bulk phy
sical consequences of deviating from exact erasure correction codes. In th
is talk\, I will take initial steps in addressing this gap of knowledge an
d discuss an intuitive tensor network model that corresponds to a tunable
class of approximate holographic codes. We find that features analogous to
gravity can emerge when "quantum noise" is injected into such holographic
stabilizer codes.\n
LOCATION:https://stable.researchseminars.org/talk/IASQubit2021/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Juan Pedraza (University of Barcelona)
DTSTART:20211206T213000Z
DTEND:20211206T221500Z
DTSTAMP:20260404T094338Z
UID:IASQubit2021/6
DESCRIPTION:Title: Lorentzian Threads and Holographic Complexity\nby Juan Ped
raza (University of Barcelona) as part of Workshop on Quantum Information
and Spacetime\n\nLecture held in Wolfensohn Hall.\n\nAbstract\nThe continu
ous min flow-max cut principle is used to reformulate the 'complexity=volu
me' conjecture using Lorentzian flows. Conceptually\, discretized flows ar
e interpreted in terms of `gatelines'\, one-dimensional time-like curves t
hat connect layers of a tensor network grid in the bulk spacetime. We imag
ine each gateline represents a unitary operation such that the bulk calcul
ation for complexity matches its information-theoretic definition. The bul
k symplectic potential provides a 'canonical' flow configuration character
izing perturbations around arbitrary CFT states. Its consistency requires
the bulk to obey linearized Einstein's equations\, which are shown to be e
quivalent to the holographic first law of complexity\, thereby advocating
a notion of 'spacetime complexity'. Finally\, we explain the need for a mo
re general measure of complexity that captures the role of suboptimal flow
s or tensor network configurations. Based on 2105.12735 and 2106.12585.\n
LOCATION:https://stable.researchseminars.org/talk/IASQubit2021/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Felix M. Haehl (Institute for Advanced Study)
DTSTART:20211206T221500Z
DTEND:20211206T230000Z
DTSTAMP:20260404T094338Z
UID:IASQubit2021/7
DESCRIPTION:Title: Spin Glasses and Holography\nby Felix M. Haehl (Institute
for Advanced Study) as part of Workshop on Quantum Information and Spaceti
me\n\nLecture held in Wolfensohn Hall.\n\nAbstract\nThe connections betwee
n disordered quantum systems (specifically the SYK model)\, ensemble avera
ging\, and two-dimensional dilaton gravity underlie much of the recent pro
gress on holography and quantum gravity. I will discuss simple disordered
systems\, which exhibit spin glass order and allow for an analytical treat
ment in certain limits. I will focus on some of their properties that are
of interest from a gravitational point of view (such as thermodynamics and
quantum chaos) and propose a holographic interpretation.\n
LOCATION:https://stable.researchseminars.org/talk/IASQubit2021/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tatsuma Nishioka (Yukawa Institute for Theoretical Physics\, Kyoto
University)
DTSTART:20211207T140000Z
DTEND:20211207T144500Z
DTSTAMP:20260404T094338Z
UID:IASQubit2021/8
DESCRIPTION:Title: Topological Pseudo Entropy\nby Tatsuma Nishioka (Yukawa In
stitute for Theoretical Physics\, Kyoto University) as part of Workshop on
Quantum Information and Spacetime\n\nLecture held in Wolfensohn Hall.\n\n
Abstract\nRecently\, a new quantum information measure called pseudo entro
py was introduced as a generalization of entanglement entropy to quantify
quantum correlation between initial and final states in a time-dependent s
ystem. In this talk\, I will examine some aspects of pseudo entropy in top
ological field theory and conformal field theory (CFT). In three-dimension
al Chern-Simons theory\, pseudo entropy can be given by a partition functi
on on a three-sphere with Wilson loops in a similar manner to topological
entanglement entropy. I will also show that the pseudo entropy in a certai
n setup is equivalent to the interface entropy in two-dimensional CFTs\, a
nd leverage the equivalence to calculate the pseudo entropies in particula
r examples. Furthermore\, I will define a pseudo entropy extension of the
left-right entanglement entropy in two-dimensional boundary CFTs and deriv
e a universal formula for a pair of arbitrary boundary states.\n
LOCATION:https://stable.researchseminars.org/talk/IASQubit2021/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Pengfei Zhang (Caltech)
DTSTART:20211207T144500Z
DTEND:20211207T153000Z
DTSTAMP:20260404T094338Z
UID:IASQubit2021/9
DESCRIPTION:Title: Branching Time in SYK-like Models\nby Pengfei Zhang (Calte
ch) as part of Workshop on Quantum Information and Spacetime\n\nLecture he
ld in Wolfensohn Hall.\n\nAbstract\nThe branching time in SYK-like models
is defined as the average time separation of rungs when computing the out-
of-time-order correlator. We argue that a parametrically large branching t
ime is necessary to obtain holographic models with non-trivial bulk dynami
cs. 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 also derive a relation between the branching time\, the Lyapunov expo
nent\, and the quasiparticle lifetime in the weak coupling limit.\n
LOCATION:https://stable.researchseminars.org/talk/IASQubit2021/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ying Zhao (University of California\, Santa Barbara)
DTSTART:20211207T161500Z
DTEND:20211207T170000Z
DTSTAMP:20260404T094338Z
UID:IASQubit2021/10
DESCRIPTION:Title: Quantum Circuit and Collisions in the Black Hole Interior
\nby Ying Zhao (University of California\, Santa Barbara) as part of Works
hop on Quantum Information and Spacetime\n\nLecture held in Wolfensohn Hal
l.\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/IASQubit2021/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Shaokai Jian (Brandeis University)
DTSTART:20211207T170000Z
DTEND:20211207T174500Z
DTSTAMP:20260404T094338Z
UID:IASQubit2021/11
DESCRIPTION:Title: Late Time von Neumann Entropy and Measurement-induced Phase T
ransition\nby Shaokai Jian (Brandeis University) as part of Workshop o
n Quantum Information and Spacetime\n\nLecture held in Wolfensohn Hall.\n\
nAbstract\nWe present our studies on the late-time von Neumann entropy and
its transition in Brownian SYK models. Without measurement\, we show that
the correlations between different replicas account for the Page curve at
late time\, and a permutation group structure emerges in the calculation.
In the presence of measurements\, we show that a continuous von Neumann e
ntropy transition from volume-law to area-law occurs at the point of repli
ca symmetry breaking.\n
LOCATION:https://stable.researchseminars.org/talk/IASQubit2021/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Phil Saad (Institute for Advanced Study)
DTSTART:20211207T194500Z
DTEND:20211207T203000Z
DTSTAMP:20260404T094338Z
UID:IASQubit2021/12
DESCRIPTION:Title: Comments on Wormholes and Factorization\nby Phil Saad (In
stitute for Advanced Study) as part of Workshop on Quantum Information and
Spacetime\n\nLecture held in Wolfensohn Hall.\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/IASQubit2021/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jorrit Kruthoff (Stanford University)
DTSTART:20211207T213000Z
DTEND:20211207T221500Z
DTSTAMP:20260404T094338Z
UID:IASQubit2021/13
DESCRIPTION:Title: Gravity Factorized\nby Jorrit Kruthoff (Stanford Universi
ty) as part of Workshop on Quantum Information and Spacetime\n\nLecture he
ld in Wolfensohn Hall.\n\nAbstract\nIn this talk I will discuss models of
two-dimensional gravity that resolve the factorization puzzle and have a d
iscrete spectrum\, whilst retaining a semiclassical description. A novelty
of these models is that they contain non-trivially correlated spacetime b
ranes or\, equivalently\, nonlocal interactions in their action. Demanding
factorization fixes almost all brane correlators\, and the exact geometri
c expansion of the partition function collapses to only two terms: the bla
ck hole saddle and a subleading "half-wormhole" geometry\, whose sum yield
s the desired discrete spectrum. Non-perturbatively\, the correlated brane
s are a certain multitrace interaction and I will show how it results in a
factorizing theory with discrete spectrum. I will end with a few comments
on the relevance of wormholes and higher dimensions.\n
LOCATION:https://stable.researchseminars.org/talk/IASQubit2021/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Luca Iliesiu (Stanford University)
DTSTART:20211207T221500Z
DTEND:20211207T230000Z
DTSTAMP:20260404T094338Z
UID:IASQubit2021/14
DESCRIPTION:Title: The Volume of the Black Hole Interior at Late Times\nby L
uca Iliesiu (Stanford University) as part of Workshop on Quantum Informati
on and Spacetime\n\nLecture held in Wolfensohn Hall.\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/IASQubit2021/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Suvrat Raju (International Centre for Theoretical Sciences\, Benga
luru)
DTSTART:20211208T140000Z
DTEND:20211208T144500Z
DTSTAMP:20260404T094338Z
UID:IASQubit2021/15
DESCRIPTION:Title: Failure of the Split Property in Gravity and the Information
Paradox\nby Suvrat Raju (International Centre for Theoretical Sciences
\, Bengaluru) as part of Workshop on Quantum Information and Spacetime\n\n
Lecture held in Wolfensohn Hall.\n\nAbstract\nIn an ordinary quantum field
theory\, the "split property" implies that the state of a system can be s
pecified independently on a bounded subregion of a Cauchy slice and its co
mplement. This property does not hold for theories of gravity. It can be s
hown in specific examples that observables near the boundary of a Cauchy s
lice uniquely fix the state on the entire slice. The original formulation
of the information paradox explicitly assumed the split property and we fo
llow this assumption to isolate the precise error in Hawking's argument. A
similar assumption also underpins the monogamy paradox of Mathur and AMPS
. Finally the same assumption is used to support the common idea that the
entanglement entropy of the region outside a black hole should follow a Pa
ge curve. It is for this reason that recent computations of the Page curve
have been performed only in nonstandard theories of gravity\, which inclu
de a nongravitational bath and massive gravitons. We discuss possibilities
for coarse graining that might lead to a Page curve in standard theories
of gravity.\n
LOCATION:https://stable.researchseminars.org/talk/IASQubit2021/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Thomas Hertog (Katholieke Universiteit\, Leuven)
DTSTART:20211208T144500Z
DTEND:20211208T153000Z
DTSTAMP:20260404T094338Z
UID:IASQubit2021/16
DESCRIPTION:Title: A Page-like Transition in Quantum Cosmology\nby Thomas He
rtog (Katholieke Universiteit\, Leuven) as part of Workshop on Quantum Inf
ormation and Spacetime\n\nLecture held in Wolfensohn Hall.\nAbstract: TBA\
n
LOCATION:https://stable.researchseminars.org/talk/IASQubit2021/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Arvin Shahbazi-Moghaddam (Stanford University)
DTSTART:20211208T161500Z
DTEND:20211208T170000Z
DTSTAMP:20260404T094338Z
UID:IASQubit2021/17
DESCRIPTION:Title: Island Finder and Singularity Theorem\nby Arvin Shahbazi-
Moghaddam (Stanford University) as part of Workshop on Quantum Information
and Spacetime\n\nLecture held in Wolfensohn Hall.\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/IASQubit2021/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Adam Levine (Institute for Advanced Study)
DTSTART:20211208T170000Z
DTEND:20211208T174500Z
DTSTAMP:20260404T094338Z
UID:IASQubit2021/18
DESCRIPTION:Title: Scattering Strings Off Quantum Extremal Surfaces\nby Adam
Levine (Institute for Advanced Study) as part of Workshop on Quantum Info
rmation and Spacetime\n\nLecture held in Wolfensohn Hall.\n\nAbstract\nI w
ill discuss recent work on a Hayden & Preskill like setup for both maximal
ly chaotic and sub- maximally chaotic quantum field theories. I will discu
ss computations of various quantum information measures on the boundary th
at tell us when a particle has left the entanglement wedge of a given regi
on. In a maximally chaotic theory\, these measures indicate a sharp transi
tion where the particle enters the wedge exactly when the insertion is nul
l separated from the quantum extremal surface for r. For sub-maximally cha
otic theories\, we find a smoothed crossover at a delayed time given in te
rms of the smaller Lyapunov exponent and dependent on the time-smearing sc
ale of the probe excitation. I will speculate on the extent to which our r
esults reveal properties of the target of the probe excitation as a “str
ingy quantum extremal surface” or simply quantify the probe itself thus
giving a new approach to studying the notion of longitudinal string spread
ing.\n
LOCATION:https://stable.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:20260404T094338Z
UID:IASQubit2021/19
DESCRIPTION:Title: One-Shot Holography\nby Geoffrey Pennington (University o
f California\, Berkeley & Institute for Advanced Study) as part of Worksho
p on Quantum Information and Spacetime\n\nLecture held in Wolfensohn Hall.
\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/IASQubit2021/19/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alexey Milekhin (University of California\, Santa Barbara)
DTSTART:20211208T194500Z
DTEND:20211208T203000Z
DTSTAMP:20260404T094338Z
UID:IASQubit2021/20
DESCRIPTION:Title: Charge Fluctuation Entropy of Hawking Radiation: A Replica-fr
ee Way to Find Large Entropy\nby Alexey Milekhin (University of Califo
rnia\, Santa Barbara) as part of Workshop on Quantum Information and Space
time\n\nLecture held in Wolfensohn Hall.\n\nAbstract\nWe study the fluctua
tion entropy for two-dimensional matter systems with an internal symmetry
coupled to Jackiw--Teitelboim(JT) gravity joined to a Minkowski region. Th
e fluctuation entropy is the Shannon entropy associated with probabilities
of finding a particular charge in a region. We first consider a case wher
e the matter has a global symmetry. We find that the fluctuation entropy o
f Hawking radiation shows an unbounded growth and exceeds the entanglement
entropy in the presence of islands. This indicates that the global symmet
ry is violated. We then discuss the fluctuation entropy for matter coupled
to a two-dimensional gauge field. We find a lower bound on the gauge coup
ling g_0 in order to avoid a similar issue. Also\, we point out a few puzz
les related to the island prescription in presence of a gauge symmetry.\nB
ased on: https://arxiv.org/abs/2109.03841 in collaboration with Amirhossei
n Tajdini\n
LOCATION:https://stable.researchseminars.org/talk/IASQubit2021/20/
END:VEVENT
END:VCALENDAR