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BEGIN:VEVENT
SUMMARY:Holographic Quantum Simulation with Atoms and Photons
DTSTART:20230801T170000Z
DTEND:20230801T174500Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-792@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Monika Schleier-Smith (Stanford University)\n\nhttps
://events.perimeterinstitute.ca/event/43/contributions/792/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/792/
END:VEVENT
BEGIN:VEVENT
SUMMARY:It from Qubit: The Game Show
DTSTART:20230804T174500Z
DTEND:20230804T183000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-816@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Patrick Hayden (Stanford University)\n\nhttps://even
ts.perimeterinstitute.ca/event/43/contributions/816/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/816/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Euclidean Wormholes and Gravity as an Average
DTSTART:20230802T170000Z
DTEND:20230802T174500Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-798@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Alexander Maloney (McGill University)\n\nhttps://eve
nts.perimeterinstitute.ca/event/43/contributions/798/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/798/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Talk 33 - Microscopic origin of the entropy of black holes
DTSTART:20230803T140000Z
DTEND:20230803T143000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-804@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Javier Magan (Instituto Balseiro)\n\nWe present a c
onstruction in which the origin of black hole entropy gets clarified. We s
tart by building an infinite family of geometric microstates for black hol
es in general relativity. This construction naively overcounts the Bekenst
ein-Hawking entropy. We then describe how wormholes in the Euclidean path
integral for gravity cause these states to have exponentially small\, but
universal\, overlaps. These overlaps recontextualize the Gibbons-Hawking t
hermal partition function. We finally show how these results imply that th
e microstates span a Hilbert space of log dimension equal to the Bekenstei
n-Hawking entropy\, and how they clarify the nature of the volumes of Eisn
tein-Rosen bridges.\n\nhttps://events.perimeterinstitute.ca/event/43/contr
ibutions/804/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/804/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sparse random Hamiltonians are quantumly easy
DTSTART:20230802T174500Z
DTEND:20230802T183000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-799@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Chi-Fang (Anthony) Chen (Caltech)\n\nhttps://events.
perimeterinstitute.ca/event/43/contributions/799/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/799/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Complexity = (almost) anything
DTSTART:20230801T174500Z
DTEND:20230801T183000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-789@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Robert Myers (Perimeter Institute)\n\nhttps://events
.perimeterinstitute.ca/event/43/contributions/789/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/789/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Talk 74 - The Riemann Zeta Function\, Poincare Recurrence\, and th
e Spectral Form Factor
DTSTART:20230803T150000Z
DTEND:20230803T153000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-806@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Michael Winer (University of Maryland)\n\nThe Spectr
al Form Factor is an important diagnostic of level repulsion Random Matrix
Theory (RMT) and quantum chaos. The short-time behavior of the SFF as it
approaches the RMT result acts as a diagnostic of the ergodicity of the sy
stem as it approaches the thermal state. In this work we observe that for
systems without time-reversal symmetry\, there is a second break from the
RMT result at late times: specifically at the Heisenberg Time $T_H=2\\pi \
\rho$. That is to say that after agreeing with the RMT result to exponenti
al precision for an amount of time exponential in the system size\, the sp
ectral form factor of a large system will very briefly deviate in a way ex
actly determined by its early time thermalization properties. The conceptu
al reason for this is the Riemann-Siegel Lookalike formula\, a resummed ex
pression for the spectral determinant relating late time behavior to early
time spectral statistics. We use the lookalike formula to derive a precis
e expression for the late time SFF for semiclassical systems\, and then co
nfirm our results numerically. We find that at late times\, the various mo
des act on the SFF via repeated\, which may give hints as to the analogous
behavior for systems with time-reversal symmetry.\n\nhttps://events.perim
eterinstitute.ca/event/43/contributions/806/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/806/
END:VEVENT
BEGIN:VEVENT
SUMMARY:An SYK model with a scaling similarity.
DTSTART:20230731T170000Z
DTEND:20230731T174500Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-782@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Juan Maldacena (Institute for Advanced Study)\n\nWe
describe supersymmetric SYK models which display a scaling similarity at l
ow temperatures\, rather than the usual conformal behavior. We discuss the
large N equations\, which were studied previously as uncontrolled approxi
mations to other models. We also present a picture for the physics of the
model which suggest that the relevant low energy degrees of freedom are al
most free. We also searched for a spin glass phase but we found no replica
symmetry breaking solutions.\n\nhttps://events.perimeterinstitute.ca/even
t/43/contributions/782/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/782/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A symmetry algebra in double-scaled SYK
DTSTART:20230803T170000Z
DTEND:20230803T174500Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-807@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Douglas Stanford (Stanford University)\n\nhttps://ev
ents.perimeterinstitute.ca/event/43/contributions/807/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/807/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Type I Von Neumann algebras from bulk path integrals: RT as entrop
y without AdS/CFT
DTSTART:20230802T213000Z
DTEND:20230802T221500Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-808@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Donald Marolf (University of California\, Santa Barb
ara)\n\nhttps://events.perimeterinstitute.ca/event/43/contributions/808/
URL:https://events.perimeterinstitute.ca/event/43/contributions/808/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Supersymmetry in quantum complexity: clique homology is QMA_1-hard
DTSTART:20230804T170000Z
DTEND:20230804T174500Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-815@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Tamara Kohler (Instituto de Ciencias Matemáticas)\n
\nIn this talk I will present recent results about the computational compl
exity of determining homology groups of simplicial complexes\, a fundament
al task in computational topology. In arXiv:2209.11793 we showed that this
decision problem is QMA1-hard. Moreover\, we showed that a version of the
problem satisfying a suitable promise is contained in QMA. This suggests
that the seemingly classical problem may in fact be quantum mechanical. I
n fact\, we were able to significantly strengthen this by showing that the
problem remains QMA1-hard in the case of clique complexes\, a family of s
implicial complexes specified by a graph which is relevant to the problem
of topological data analysis. The proof combines a number of techniques fr
om Hamiltonian complexity and homological algebra\, and is inspired by a l
ink with supersymmetric quantum mechanics. In this talk I will focus on ho
w the link with supersymmetry inspired the result\, and explain the intuit
ion behind the proof.\n\nhttps://events.perimeterinstitute.ca/event/43/con
tributions/815/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/815/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Talk 124 - von Neumann algebras in JT gravity with matter
DTSTART:20230731T143000Z
DTEND:20230731T150000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-780@events.perimeterinstitute.ca
DESCRIPTION:Speakers: David Kolchmeyer (Massachusetts Institute of Technol
ogy)\n\nWe quantize JT gravity with matter on the spatial interval with tw
o asymptotically AdS boundaries. We consider the von Neumann algebra gener
ated by the right Hamiltonian and the gravitationally dressed matter opera
tors on the right boundary. We prove that the commutant of this algebra is
the analogously defined left boundary algebra and that both algebras are
type II infinity factors. These algebras provide a precise notion of the e
ntanglement wedge away from the semiclassical limit.\n\nhttps://events.per
imeterinstitute.ca/event/43/contributions/780/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/780/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Talk 106 - Holographic Codes from Hyperinvariant Tensor Networks
DTSTART:20230801T140000Z
DTEND:20230801T143000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-786@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Alexander Jahn (Free University of Berlin)\n\nHologr
aphic quantum-error correcting codes are models of bulk/boundary dualities
such as the anti-de Sitter/conformal field theory (AdS/CFT) correspondenc
e\, where a higher-dimensional bulk geometry is associated with the code's
logical degrees of freedom. Previous discrete holographic codes based on
tensor networks have reproduced the general code properties expected from
continuum AdS/CFT\, such as complementary recovery. However\, the boundary
states of such tensor networks typically do not exhibit the expected corr
elation functions of CFT boundary states. \nIn this work\, we show that a
new class of exact holographic codes\, extending the previously proposed h
yperinvariant tensor networks into quantum codes\, produce the correct bou
ndary correlation functions. This approach yields a dictionary between log
ical states in the bulk and the critical renormalization group flow of bou
ndary states. Furthermore\, these codes exhibit a state-dependent breakdow
n of complementary recovery as expected from AdS/CFT under small quantum g
ravity corrections.\n\nhttps://events.perimeterinstitute.ca/event/43/contr
ibutions/786/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/786/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Talk 2 - Large N Matrix Quantum Mechanics as a Quantum Memory
DTSTART:20230804T133000Z
DTEND:20230804T140000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-811@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Gong Cheng (University of Maryland)\n\nIn this paper
\, we explore the possibility of building a quantum memory that is robust
to thermal noise using large N matrix quantum mechanics models. First\, we
investigate the gauged SU(N) matrix harmonic oscillator and different way
s to encode quantum information in it. By calculating the mutual informati
on between the system and a reference which purifies the encoded informati
on\, we identify a transition temperature\, Tc\, below which the encoded q
uantum information is protected from thermal noise for a memory time scali
ng as N^2. Conversely\, for temperatures higher than T_c\, the information
is quickly destroyed by thermal noise. Second\, we relax the requirement
of gauge invariance and study a matrix harmonic oscillator model with only
global symmetry. Finally\, we further relax even the symmetry requirement
and propose a model that consists of a large number N^2 of qubits\, with
interactions derived from an approximate SU(N) symmetry. In both ungauged
models\, we find that the effects of gauging can be mimicked using an ener
gy penalty to give a similar result for the memory time. The final qubit m
odel also has the potential to be realized in the laboratory.\n\nhttps://e
vents.perimeterinstitute.ca/event/43/contributions/811/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/811/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Talk 10 - Constraints on physical computers in holographic spaceti
mes
DTSTART:20230801T203000Z
DTEND:20230801T210000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-791@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Alex May (Perimeter Institute)\n\nWithin the setting
of the AdS/CFT correspondence\, we ask about the power of computers in th
e presence of gravity. We show that there are computations on $n$ qubits w
hich cannot be implemented inside of black holes with entropy less than $O
(2^n)$. To establish our claim\, we argue computations happening inside th
e black hole must be implementable in a programmable quantum processor\, s
o long as the inputs and description of the unitary to be run are not too
large. We then prove a bound on quantum processors which shows many unitar
ies cannot be implemented inside the black hole\, and further show some of
these have short descriptions and act on small systems. These unitaries w
ith short descriptions must be computationally forbidden from happening in
side the black hole.\n\nhttps://events.perimeterinstitute.ca/event/43/cont
ributions/791/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/791/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Talk 16 - Toward random tensor networks and holographic codes in C
FT
DTSTART:20230801T150000Z
DTEND:20230801T153000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-788@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Jeevan Chandra Namburi (Cornell University)\n\nIn ho
lographic CFTs satisfying eigenstate thermalization\, there is a regime wh
ere the operator product expansion can be approximated by a random tensor
network. The geometry of the tensor network corresponds to a spatial slice
in the holographic dual\, with the tensors discretizing the radial direct
ion. In spherically symmetric states in any dimension and more general sta
tes in 2d CFT\, this leads to a holographic error-correcting code\, define
d in terms of OPE data\, that can be systematically corrected beyond the r
andom tensor approximation. The code is shown to be isometric for light op
erators outside the horizon\, and non-isometric inside\, as expected from
general arguments about bulk reconstruction. The transition at the horizon
occurs due to a subtle breakdown of the Virasoro identity block approxima
tion in states with a complex interior.\n\nhttps://events.perimeterinstitu
te.ca/event/43/contributions/788/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/788/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Talk 44 - Large N von Neumann Algebras and the renormalization of
Newton's constant
DTSTART:20230731T133000Z
DTEND:20230731T140000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-778@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Elliot Gesteau (Caltech)\n\nIn holography\, the quan
tum extremal surface formula relates the entropy of a boundary state to th
e sum of two terms: the area term and the entropy of bulk fields inside th
e entanglement wedge. As the bulk effective field theory suffers from UV d
ivergences\, the second term must be regularized. It has been conjectured
since the work of Susskind and Uglum that the renormalization of Newton’
s constant in the area term exactly cancels the difference between differe
nt choices of regularization for bulk entropy. In this talk\, I will expla
in how the recent developments on von Neumann algebras appearing in the la
rge N limit of holography allow to prove this claim within the framework o
f holographic quantum error correction\, and to reinterpret it as an insta
nce of the ER=EPR paradigm. This talk is based on the paper arXiv:2302.019
38.\n\nhttps://events.perimeterinstitute.ca/event/43/contributions/778/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/778/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Talk 17 - Channeling quantum criticality
DTSTART:20230802T150000Z
DTEND:20230802T153000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-797@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Yijian Zou (Stanford University)\n\nWe analyze the e
ffect of decoherence\, modelled by local quantum channels\, on quantum cri
tical states and we find universal properties of the resulting mixed state
's entanglement\, both between system and environment and within the syste
m. Renyi entropies exhibit volume law scaling with a subleading constant g
overned by a "g-function" in conformal field theory (CFT)\, allowing us to
define a notion of renormalization group (RG) flow (or "phase transitions
") between quantum channels. We also find that the entropy of a subsystem
in the decohered state has a subleading logarithmic scaling with subsystem
size\, and we relate it to correlation functions of boundary condition ch
anging operators in the CFT. Finally\, we find that the subsystem entangle
ment negativity\, a measure of quantum correlations within mixed states\,
can exhibit log scaling or area law based on the RG flow. When the channel
corresponds to a marginal perturbation\, the coefficient of the log scali
ng can change continuously with decoherence strength. We illustrate all th
ese possibilities for the critical ground state of the transverse-field Is
ing model\, in which we identify four RG fixed points of dephasing channel
s and verify the RG flow numerically. Our results are relevant to quantum
critical states realized on noisy quantum simulators\, in which our predic
ted entanglement scaling can be probed via shadow tomography methods.\n\nh
ttps://events.perimeterinstitute.ca/event/43/contributions/797/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/797/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Talk 22 - Microstates of a 2d Black Hole in string theory
DTSTART:20230803T133000Z
DTEND:20230803T140000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-803@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Panos Betzios (University of British Columbia)\n\nWe
analyse models of Matrix Quantum Mechanics in the double scaling limit th
at contain non-singlet states. The finite temperature partition function o
f such systems contains non-trivial winding modes (vortices) and is expres
sed in terms of a group theoretic sum over representations. We then focus
on the model of Kazakov-Kostov-Kutasov when the first winding mode is domi
nant. In the limit of large representations (continuous Young diagrams)\,
and depending on the values of the parameters of the model such as the com
pactification radius and the string coupling\, the dual geometric backgrou
nd corresponds either to that of a long string (winding mode) condensate o
r a 2d (non-supersymmetric) semi-classical Black Hole competing with the t
hermal linear dilaton background. In the matrix model we are free to tune
these parameters and explore various regimes of this phase diagram. Our co
nstruction allows us to identify the origin of the microstates of the long
string condensate/2d Black Hole arising from the non trivial representati
ons.\n\nhttps://events.perimeterinstitute.ca/event/43/contributions/803/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/803/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Talk 29 - Any consistent coupling between classical gravity and q
uantum matter is fundamentally irreversible
DTSTART:20230802T200000Z
DTEND:20230802T203000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-800@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Flaminia Giacomini (ETH Zurich)\n\nWhen gravity is s
ourced by a quantum system\, there is tension between its role as the medi
ator of a fundamental interaction\, which is expected to acquire nonclassi
cal features\, and its role in determining the properties of spacetime\, w
hich is inherently classical. Fundamentally\, this tension should result i
n breaking one of the fundamental principles of quantum theory or general
relativity\, but it is usually hard to assess which one without resorting
to a specific model. Here\, we answer this question in a theory-independen
t way using General Probabilistic Theories (GPTs). We consider the interac
tions of the gravitational field with a single matter system\, and derive
a no-go theorem showing that when gravity is classical at least one of the
following assumptions needs to be violated: (i) Matter degrees of freedom
are described by fully non-classical degrees of freedom\; (ii) Interactio
ns between matter degrees of freedom and the gravitational field are rever
sible\; (iii) Matter degrees of freedom back-react on the gravitational fi
eld. We argue that this implies that theories of classical gravity and qua
ntum matter must be fundamentally irreversible\, as is the case in the rec
ent model of Oppenheim et al. Conversely if we require that the interactio
n between quantum matter and the gravitational field are reversible\, then
the gravitational field must be non-classical.\n\nhttps://events.perimete
rinstitute.ca/event/43/contributions/800/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/800/
END:VEVENT
BEGIN:VEVENT
SUMMARY:talk 30 - Measurement-based quantum simulation of Abelian lattice
gauge theories
DTSTART:20230802T133000Z
DTEND:20230802T140000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-794@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Hiroki Sukeno (Stony Brook University)\n\nQuantum si
mulation of lattice gauge theory is expected to become a major application
of near-term quantum devices. In this presentation\, I will talk about a
quantum simulation scheme for lattice gauge theories motivated by Measurem
ent-Based Quantum Computation [1]\, which we call Measurement-Based Quantu
m Simulation (MBQS). In MBQS\, we consider preparing a resource state whos
e entanglement structure reflects the spacetime structure of the simulated
gauge theory. We then consider sequentially measuring qubits in the resou
rce state in a certain adaptive manner\, which drives the time evolution i
n the Hamiltonian lattice gauge theory. It turns out that the resource sta
tes we use for MBQS of Wegner’s models possess topological order protect
ed by higher-form symmetries. These higher-form symmetries are also practi
cally useful for error correction to suppress contributions that violate g
auge symmetries. We also discuss the relation between the resource state a
nd the partition function of Wegner’s model. This presentation is based
on my work with Takuya Okuda [2]. \n\n[1] R. Raussendorf and H. J. Briegel
\, A One-Way Quantum Computer\, Phys. Rev. Lett. 86\, 5188 (2001)\n[2] H.
Sukeno and T. Okuda\, Measurement-based quantum simulation of Abelian latt
ice gauge theories\, arXiv:2210.10908\n\nhttps://events.perimeterinstitute
.ca/event/43/contributions/794/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/794/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Talk 41 - Mutual Information of Holographic Generalized Free Field
s
DTSTART:20230731T203000Z
DTEND:20230731T210000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-784@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Pedro Jorge Martinez (Instituto Balseiro)\n\nWe stud
y Generalized Free Fields (GFF) from the point of view of information meas
ures. We begin by reviewing conformal GFF\, their holographic representati
on\, and the multiple possible assignations of algebras to a single spacet
ime region that arise in these theories. We will focus on manifestations o
f these features present in the Mutual Information (MI) of holographic GFF
. First\, we show that the MI can be expected to be finite even if the AdS
dual space is of infinite volume. Then\, we present the long-distance lim
it of the MI for regions with arbitrary boundaries in the light cone for t
he causal and entanglement wedge algebras. The pinching limit of these sur
faces shows the GFF behaves as an interacting model from the MI point of v
iew. The entanglement wedge algebra choice allows these models to ``fake''
causality\, giving results consistent with their role in the description
of large N models. Finally\, we explore the short distance limit of the MI
. Interestingly\, we find that the GFF has a leading volume term rather th
an an area term and a logarithmic term in any dimension rather than only f
or even dimensions as in ordinary CFTs. We also find the dependence of som
e subleading terms on the conformal dimension of the GFF.\n\nhttps://event
s.perimeterinstitute.ca/event/43/contributions/784/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/784/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Talk 61 - Horizons are Watching You
DTSTART:20230731T150000Z
DTEND:20230731T153000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-781@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Gautam Satishchandran (Princeton University)\n\nWe s
how that if a massive (or charged) body is put in a quantum superposition
of spatially separated states in the vicinity of any (Killing) horizon\, t
he mere presence of the horizon will eventually destroy the coherence of t
he superposition in a finite time. This occurs because\, in effect\, the l
ong-range fields sourced by the superposition register on the black hole h
orizon which forces the emission of entangling “soft gravitons/photons
” through the horizon. This enables the horizon to harvest “which path
” information about the superposition. We provide estimates of the decoh
erence time for such quantum superpositions in the presence of a black hol
e and cosmological horizon. Finally\, we further sharpen and generalize th
is mechanism by recasting the gedankenexperiment in the language of (appro
ximate) quantum error correction. This yields a complementary picture wher
e the decoherence is due to an “eavesdropper” (Eve) in the black hole
attempting to obtain "which path" information by measuring the long-range
fields of the superposed body. We explicitly compute the quantum fidelity
to determine the amount of information such an Eve can obtain and show\, b
y the information-disturbance tradeoff\, a direct relationship between the
information gained by Eve and the decoherence of the superposition in the
exterior. In particular\, we show that the decoherence of the superpositi
on corresponds to the "optimal" measurement made by Eve in the black hole
interior.\n\nhttps://events.perimeterinstitute.ca/event/43/contributions/7
81/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/781/
END:VEVENT
BEGIN:VEVENT
SUMMARY:(VIRTUAL) Talk 63 - Measurement-induced phase transition in telepo
rtation and wormholes
DTSTART:20230802T140000Z
DTEND:20230802T143000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-795@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Alexey Milekhin (University of California\, Santa Ba
rbara)\n\nWe demonstrate that some quantum teleportation protocols exhibit
measurement induced phase transitions in Sachdev-Ye-Kitaev model. Namely\
, Kitaev-Yoshida and Gao-Jafferis-Wall protocols have a phase transition i
f we apply them at a large projection rate or at a large coupling rate res
pectively. It is well-known that at small rates they allow teleportation t
o happen only within a small time-window. We show that at large rates\, th
e system goes into a new steady state\, where the teleportation can be per
formed at any moment. In dual Jackiw-Teitelboim gravity these phase transi
tions correspond to the formation of an eternal traversable wormhole. In t
he Kitaev-Yoshida case this novel type of wormhole is supported by continu
ous projections. Based on https://arxiv.org/abs/2210.03083\n\nhttps://even
ts.perimeterinstitute.ca/event/43/contributions/795/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/795/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Merged talks - An effective field theory for non-maximal quantum c
haos\; 66- Effective description of sub-maximal chaos: stringy effects for
SYK scrambling
DTSTART:20230803T174500Z
DTEND:20230803T183000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-810@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Felix Haehl (University of Southampton)\, Ping Gao (
Massachusetts Institute of Technology)\n\n66 - It has been proposed that t
he exponential decay and subsequent power law saturation of out-of-time-or
der correlation functions can be universally described by collective 'scra
mblon' modes. We develop this idea from a path integral perspective in sev
eral examples\, thereby establishing a general formalism. After reformulat
ing previous work on the Schwarzian theory and identity conformal blocks i
n two-dimensional CFTs relevant for systems in the infinite coupling limit
with maximal quantum Lyapunov exponent\, we focus on theories with sub-ma
ximal chaos: we study the large-q limit of the SYK quantum dot and chain\,
both of which are amenable to analytical treatment at finite coupling. In
both cases we identify the relevant scramblon modes\, derive their effect
ive action\, and find bilocal vertex functions\, thus constructing an effe
ctive description of chaos. The final results can be matched in detail to
stringy corrections to the gravitational eikonal S-matrix in holographic C
FTs\, including a stringy Regge trajectory\, bulk to boundary propagators\
, and multi-string effects that are unexplored holographically.\n\nhttps:/
/events.perimeterinstitute.ca/event/43/contributions/810/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/810/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Talk 67 - Irreversibility\, QNEC\, and defects
DTSTART:20230731T200000Z
DTEND:20230731T203000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-783@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Gonzalo Torroba (Centro Atomico Bariloche\, Argentin
a)\n\nIn this talk\, we will first present an analysis of infinitesimal nu
ll deformations for the entanglement entropy\, which leads to a major simp
lification of the proof of the C\, F and A-theorems in quantum field theor
y. Next\, we will discuss the quantum null energy condition (QNEC) on the
light-cone. Finally\, we combine these tools in order to establish the irr
eversibility of renormalization group flows on planar d-dimensional defect
s\, embedded in D-dimensional conformal field theories. This proof complet
es and unifies all known defect irreversibility theorems for defect dimens
ions below d=5. The F-theorem on defects (d=3) is a new result using infor
mation-theoretic methods. The geometric construction connects the proof of
irreversibility with and without defects through the QNEC inequality in t
he bulk\, and makes contact with the proof of strong subadditivity of holo
graphic entropy taking into account quantum corrections.\n\nhttps://events
.perimeterinstitute.ca/event/43/contributions/783/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/783/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Talk 71 - Topological Toy Models for the Emergence of Spacetime.
DTSTART:20230801T143000Z
DTEND:20230801T150000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-787@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Annie Wei (Massachusetts Institute of Technology)\n\
nWe study entanglement entropy in (2+1)-dimensional gravity as a window in
to larger open questions regarding entanglement entropy in gravity. (2+1)-
dimensional gravity can be rewritten as a topological field theory\, which
makes it a more tractable model to study. In these topological theories\,
there remain key questions which we seek to answer in this work\, such as
the questions 1) What is the entropy of the physical algebra of observabl
es in a subregion\, 2) How do we define a factorization map such that the
entropy of the resulting factors agrees with this algebraic entropy\, and
3) Can we use these insights to build a tensor network that exhibits non-c
ommuting areas? We investigate non-Abelian toric codes / Levin-Wen models
as a toy model for black hole entropy in Chern Simons theory. These differ
from the usual model in that the stabilizers are implemented as constrain
ts. By enforcing constraints for both Gauss' Law and the flatness of the g
auge field\, we obtain a choice of algebra that contains only topological
operators. The desirable properties of this model are twofold: first\, we
produce the finiteness of black hole entropy described in previous literat
ure while providing a natural algebraic motivation for this result. Second
ly\, we obtain non-commuting area operators on a toy model with the topolo
gy of a torus.\n\nhttps://events.perimeterinstitute.ca/event/43/contributi
ons/787/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/787/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Talk 79 - Measurements in holographic systems: current status and
future directions
DTSTART:20230802T143000Z
DTEND:20230802T150000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-796@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Grado-White Brianna (Brandeis University)\n\nHologra
phy has taught us that spacetime is emergent and its properties depend on
the entanglement structure of the dual boundary theory. At the same time\,
we know that local projective measurements tend to destroy entanglement.
This leads to a natural question: what happens to the holographic bulk spa
cetime if we perform strong local projective measurements on a subsystem $
A$ of the boundary? In particular\, I will explain the effect of measureme
nts performed both on subsystems of a single CFT in its vacuum state\, whi
ch is dual to pure AdS spacetime\, and on various subsystems of two copies
of a CFT in the thermofield double state\, which is dual to a double-side
d AdS black hole. The post-measurement bulk is cut off by end-of-the-world
branes and is dual to the complementary unmeasured subsystem $A^c$. The m
easurement triggers an entangling/disentangling phase transition in the bo
undary theory\, corresponding to a connected/disconnected phase transition
in the bulk dual geometry. Interestingly\, the post-measurement bulk incl
udes regions that were part of the entanglement wedge of $A$ before the me
asurement\, signaling a transfer of information from the measured to the u
nmeasured subsystem analogous to quantum teleportation. Finally\, I will d
iscuss open questions and future directions related to our work\, with a p
articular focus on its consequences for the complexity of bulk reconstruct
ion.\n\nhttps://events.perimeterinstitute.ca/event/43/contributions/796/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/796/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Talk 81 - Testing the quantumness of gravity without entanglement
DTSTART:20230802T203000Z
DTEND:20230802T210000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-801@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Ludovico Lami (University of Amsterdam)\n\nWe propos
e a conceptually new class of dynamical experiments whose goal is to falsi
fy the hypothesis that an interaction between quantum systems is mediated
by a purely local classical field. The systems we study implement a dynami
cs that cannot be simulated by means of local operations and classical com
munication (LOCC)\, even when no entanglement is ever generated at any poi
nt in the process. Using tools from quantum information theory\, we estima
te the maximal fidelity of simulation that a local classical interaction c
ould attain while employing only LOCC. Under our assumptions\, if an exper
iment detects a fidelity larger than that calculated threshold\, then a lo
cal classical description of the interaction is no longer possible. As a p
rominent application of this scheme\, we study a general system of quantum
harmonic oscillators initialised in normally distributed coherent states
and interacting via Newtonian gravity\, and discuss a possible physical im
plementation with torsion pendula. One of our main technical contributions
is the calculation of the above bound on the maximal LOCC simulation fide
lity for this family of systems. As opposed to existing tests based on the
detection of gravitationally mediated entanglement\, our proposal works w
ith coherent states alone\, and thus it does not require the generation of
largely delocalised states of motion nor the detection of entanglement.\n
\nhttps://events.perimeterinstitute.ca/event/43/contributions/801/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/801/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Talk 120 - Security of position-based cryptography limits Hamilto
nian simulation via holography
DTSTART:20230801T200000Z
DTEND:20230801T203000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-790@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Harriet Apel (University College London)\n\nWe inves
tigate the link between position-based quantum cryptography (PBQC) and hol
ography established in [May19] using holographic quantum error correcting
codes as toy models. If the "temporal" scaling of the AdS metric is insert
ed by hand into the toy model via the bulk Hamiltonian interaction strengt
h we recover a toy model with consistent causality structure. This leads t
o an interesting implication between two topics in quantum information: if
position-based cryptography is secure against attacks with small entangle
ment then there are new fundamental lower bounds for resources required fo
r one Hamiltonian to simulate another.\n\nhttps://events.perimeterinstitut
e.ca/event/43/contributions/790/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/790/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Talk 84 - Complementarity and the unitarity of the black hole S-ma
trix
DTSTART:20230804T150000Z
DTEND:20230804T153000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-814@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Isaac Kim (University of California\, Davis)\n\nRece
ntly\, Akers et al. proposed a non-isometric holographic map from the inte
rior of a black hole to its exterior. Within this model\, we study propert
ies of the black hole S-matrix\, which are in principle accessible to obse
rvers who stay outside the black hole. Specifically\, we investigate a sce
nario in which an infalling agent interacts with radiation both outside an
d inside the black hole. Because the holographic map involves postselectio
n\, the unitarity of the S-matrix is not guaranteed in this scenario\, but
we find that unitarity is satisfied to very high precision if suitable co
nditions are met. If the internal black hole dynamics is described by a ps
eudorandom unitary transformation\, and if the operations performed by the
infaller have computational complexity scaling polynomially with the blac
k hole entropy\, then the S-matrix is unitary up to corrections that are s
uperpolynomially small in the black hole entropy. Furthermore\, while in p
rinciple quantum computation assisted by postselection can be very powerfu
l\, we find under similar assumptions that the S-matrix of an evaporating
black hole has polynomial computational complexity.\n\nhttps://events.peri
meterinstitute.ca/event/43/contributions/814/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/814/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Talk 88 - Type II_1 algebras for local subregions in quantum gravi
ty
DTSTART:20230731T140000Z
DTEND:20230731T143000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-779@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Antony Speranza (University of Illinois\, Urbana-Cha
mpaign)\n\nWe argue that generic local subregions in semiclassical quantum
gravity are associated with von Neumann algebras of type II_1\, extending
recent work by Chandrasekaran et.al. beyond subregions bounded by Killing
horizons. The subregion algebra arises as a crossed product of the type I
II_1 algebra of quantum fields in the subregion by the flow generated by a
gravitational constraint operator. We conjecture that this flow agrees wi
th the vacuum modular flow sufficiently well to conclude that the resultin
g algebra is type II_\\infty\, which projects to a type II_1 algebra after
imposing a positive energy condition. The entropy of semiclassical states
on this algebra can be computed and shown to agree with the generalized e
ntropy by appealing to a first law of local subregions. The existence of a
maximal entropy state for the type II_1 algebra is further shown to imply
a version of Jacobson’s entanglement equilibrium hypothesis. We discuss
other applications of this construction to quantum gravity and holography
\, including the quantum extremal surface prescription and the quantum foc
using conjecture.\n\nhttps://events.perimeterinstitute.ca/event/43/contrib
utions/779/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/779/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Talk 95 - A Large Holographic Code and its Geometric Flows
DTSTART:20230804T143000Z
DTEND:20230804T150000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-813@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Xi Dong (University of California\, Santa Barbara)\n
\nThe JLMS formula is a cornerstone in our understanding of bulk reconstru
ction in holographic theories of quantum gravity\, best interpreted as a q
uantum error-correcting code. Moreover\, recent work has highlighted the i
mportance of understanding holography as an approximate and perhaps non-is
ometric code. In this work\, we construct an enlarged code subspace for th
e bulk theory that contains multiple non-perturbatively different backgrou
nd geometries. In such a large holographic code\, we carefully derive an a
pproximate version of the JLMS formula from an approximate FLM formula for
a class of nice states. We do not assume that the code is isometric\, but
interestingly find that approximate FLM forces the code to be approximate
ly isometric. Furthermore\, we show that the bulk modular Hamiltonian of t
he entanglement wedge makes important contributions to the JLMS formula an
d cannot in general be neglected even when the bulk state is semiclassical
. Nevertheless\, when acting on states with the same background geometry\,
we find that the modular flow is well approximated by the area flow which
takes the geometric form of a boundary-condition-preserving kink transfor
m. We also generalize the results to higher derivative gravity\, where are
a is replaced by the geometric entropy. We conjecture that a Lorentzian de
finition of the geometric entropy is equivalent to its original\, Euclidea
n definition\, and we verify this conjecture in a dilaton theory with high
er derivative couplings. Thus we find that the flow generated by the geome
tric entropy takes the universal form of a boundary-condition-preserving k
ink transform.\n\nhttps://events.perimeterinstitute.ca/event/43/contributi
ons/813/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/813/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Talk 110 - NoRA: A Tensor Network Ansatz for Volume-Law Entangled
Equilibrium States of Highly Connected Hamiltonians
DTSTART:20230801T133000Z
DTEND:20230801T140000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-785@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Valérie Bettaque (Brandeis University)\n\nMotivated
by the ground state structure of quantum models with all-to-all interacti
ons such as mean-field quantum spin glass models and the Sachdev-Ye-Kitaev
(SYK) model\, we propose a tensor network architecture which can accomoda
te volume law entanglement and a large ground state degeneracy. We call th
is architecture the non-local renormalization ansatz (NoRA) because it can
be viewed as a generalization of MERA\, DMERA\, and branching MERA networ
ks with the constraints of spatial locality removed. We argue that the arc
hitecture is potentially expressive enough to capture the entanglement and
complexity of the ground space of the SYK model\, thus making it a suitab
le variational ansatz\, but we leave a detailed study of SYK to future wor
k. We further explore the architecture in the special case in which the te
nsors are random Clifford gates. Here the architecture can be viewed as th
e encoding map of a random stabilizer code. We introduce a family of codes
inspired by the SYK model which can be chosen to have constant rate and l
inear distance at the cost of some high weight stabilizers. We also commen
t on potential similarities between this code family and the approximate c
ode formed from the SYK ground space.\n\nhttps://events.perimeterinstitute
.ca/event/43/contributions/785/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/785/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Talk 118 - Overlapping qubits from non-isometric maps and de Sitte
r tensor networks
DTSTART:20230804T140000Z
DTEND:20230804T143000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-812@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Alexander Jahn (Free University of Berlin)\n\nWe con
struct approximately local observables\, or "overlapping qubits"\, using n
on-isometric maps and show that processes in local effective theories can
be spoofed with a quantum system with fewer degrees of freedom\, similar t
o our expectation in holography. Furthermore\, the spoofed system naturall
y deviates from an actual local theory in ways that can be identified with
features in quantum gravity. For a concrete example\, we construct two ME
RA toy models of de Sitter space-time and explain how the exponential expa
nsion in global de Sitter can be spoofed with many fewer quantum degrees o
f freedom and that local physics may be approximately preserved for an exc
eedingly long time before breaking down. Conceptually\, we comment on how
approximate overlapping qubits connect Hilbert space dimension verificatio
n\, degree-of-freedom counting in black holes and holography\, approximate
locality in quantum gravity\, non-isometric codes\, and circuit complexit
y.\n\nhttps://events.perimeterinstitute.ca/event/43/contributions/812/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/812/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Talk 125 - Partition function of a volume of space
DTSTART:20230803T143000Z
DTEND:20230803T150000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-805@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Manus Visser (University of Cambridge)\n\nWe conside
r the quantum gravity partition function that counts the dimension of the
Hilbert space of a spatial region with topology of a ball and fixed proper
volume\, and evaluate it in the leading order saddle point approximation.
The result is the exponential of the Bekenstein-Hawking entropy associate
d with the area of the saddle ball boundary\, and is reliable within effec
tive field theory provided the mild curvature singularity at the ball boun
dary is regulated by higher curvature terms. This generalizes the classic
Gibbons-Hawking computation of the de Sitter entropy for the case of posit
ive cosmological constant and unconstrained volume\, and hence exhibits th
e holographic nature of nonperturbative quantum gravity in generic finite
volumes of space.\n\nhttps://events.perimeterinstitute.ca/event/43/contrib
utions/805/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/805/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Talk 135 - Spectral properties of the sparse SYK model\, with anal
ysis of recent experimental simulation of holography
DTSTART:20230803T183000Z
DTEND:20230803T190000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-809@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Patrick Orman (Caltech)\n\nThe Sachdev-Ye-Kitaev (SY
K) model is a simple toy model of holography that has seen widespread stud
y in the area of quantum gravity. It is particularly notable for its feasi
bility of simulation on near-term quantum devices. Recently\, Swingle et a
l. introduced a sparsified version of the SYK model and analyzed its holog
raphic properties\, which are remarkably robust to deletion of Majorana in
teraction terms. Here we analyze its spectral and quantum chaotic properti
es as they pertain to holography as well as how they scale with sparsity a
nd system size through large scale numerics. We identify at least two tran
sition points at which features of chaos and holography are lost as the mo
del is sparsified\, and above which all important features are preserved\,
which may serve as guidelines for future experiments to simulate quantum
gravity. Additionally\, we apply these analyses to the SYK model that was
recently experimentally simulated on the Google Sycamore quantum processor
\, which itself was a highly sparsified SYK model obtained through a machi
ne learning algorithm incorporating mutual information signatures of a tra
versable wormhole.\n\nhttps://events.perimeterinstitute.ca/event/43/contri
butions/809/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/809/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Petz recovery from subsystems in conformal field theory
DTSTART:20230731T174500Z
DTEND:20230731T183000Z
DTSTAMP:20231209T191000Z
UID:indico-contribution-793@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Shreya Vardhan (Stanford University)\n\nWe probe the
multipartite entanglement structure of the vacuum state of a CFT in 1+1 d
imensions\, using recovery operations that attempt to reconstruct the dens
ity matrix in some region from its reduced density matrices on smaller sub
regions. We use an explicit recovery channel known as the twirled Petz map
\, and study distance measures such as the fidelity\, relative entropy\, a
nd trace distance between the original state and the recovered state. One
setup we study in detail involves three contiguous intervals A\, B and C o
n a spatial slice\, where we can view these quantities as measuring correl
ations between A and C that are not mediated by the region B that lies bet
ween them. We show that each of the distance measures is both UV finite an
d independent of the operator content of the CFT\, and hence depends only
on the central charge and the cross-ratio of the intervals. We evaluate th
ese universal quantities numerically using lattice simulations in critical
spin chain models\, and derive their analytic forms in the limit where A
and C are close using the OPE expansion. We also compare the mutual inform
ation between various subsystems in the original and recovered states\, wh
ich leads to a more qualitative understanding of the differences between t
hem. Further\, we introduce generalizations of the recovery operation to m
ore than three adjacent intervals\, for which the fidelity is again univer
sal with respect to the operator content.\n\nhttps://events.perimeterinsti
tute.ca/event/43/contributions/793/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/43/contributions/793/
END:VEVENT
END:VCALENDAR