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VERSION:2.0
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BEGIN:VEVENT
SUMMARY:Latent variable justifies the stronger instrumental variable bound
s
DTSTART;VALUE=DATE-TIME:20230419T203000Z
DTEND;VALUE=DATE-TIME:20230419T210000Z
DTSTAMP;VALUE=DATE-TIME:20230608T105531Z
UID:indico-contribution-38-592@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Richard Guo (University of Cambridge)\nFor binary i
nstrumental variable models\, there seems to be a long-standing gap betwee
n two sets of bounds on the average treatment effect: the stronger Balke
–Pearl ("sharp") bounds versus the weaker Robins–Manski ("natural") bo
unds. In the literature\, the Balke–Pearl bounds are typically derived u
nder stronger assumptions\, i.e.\, either individual exclusion or joint ex
ogeneity\, which are untestable cross-world statements\, while the natural
bounds only require testable assumptions. In this talk\, I show that the
stronger bounds are justified by the existence of a latent confounder. In
fact\, the Balke–Pearl bounds are sharp under latent confounding and sto
chastic exclusion. The "secret sauce" that closes this gap is a set of CHS
H-type inequalities that generalize Bell's (1964) inequality.\n\nhttps://e
vents.perimeterinstitute.ca/event/38/contributions/592/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/38/contributions/592/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Quantum causal inference in the presence of hidden common causes:
An entropic approach
DTSTART;VALUE=DATE-TIME:20230418T183000Z
DTEND;VALUE=DATE-TIME:20230418T190000Z
DTSTAMP;VALUE=DATE-TIME:20230608T105531Z
UID:indico-contribution-38-601@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Mohammad Ali Javidian (Appalachian State University)
\nQuantum causality is an emerging field of study which has the potential
to greatly advance our understanding of quantum systems. In this paper\, w
e put forth a theoretical framework for merging quantum information scienc
e and causal inference by exploiting entropic principles. For this purpose
\, we leverage the tradeoff between the entropy of hidden cause and the co
nditional mutual information of observed variables to develop a scalable a
lgorithmic approach for inferring causality in the presence of latent conf
ounders (common causes) in quantum systems. As an application\, we conside
r a system of three entangled qubits and transmit the second and third qub
its over separate noisy quantum channels. In this model\, we validate that
the first qubit is a latent confounder and the common cause of the second
and third qubits. In contrast\, when two entangled qubits are prepared an
d one of them is sent over a noisy channel\, there is no common confounder
. We also demonstrate that the proposed approach outperforms the results o
f classical causal inference for the Tubingen database when the variables
are classical by exploiting quantum dependence between variables through d
ensity matrices rather than joint probability distributions.\n\nhttps://ev
ents.perimeterinstitute.ca/event/38/contributions/601/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/38/contributions/601/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Certifying long-range quantum correlations through routed Bell exp
eriments
DTSTART;VALUE=DATE-TIME:20230420T180000Z
DTEND;VALUE=DATE-TIME:20230420T183000Z
DTSTAMP;VALUE=DATE-TIME:20230608T105531Z
UID:indico-contribution-38-595@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Stefano Pironio (Université Libre de Bruxelles)\nI
n a recent paper\, Chaturvedi et al considered the interesting idea of rou
ted Bell experiments. These are Bell experiments where Bob can measure his
quantum particles at two distinct locations\, one close to the source and
another far away. This can be accomplished in the lab by using a switch t
hat directs Bob's quantum particle either to the nearby measurement device
or to the distant one\, depending on a classical input chosen by Bob. Cha
turvedi et al argue that there exists in such experiments a tradeoff betwe
en short-range and long-range correlations and that high-quality CHSH test
s close to the source (which are achievable with current technology) lower
the requirements for witnessing nonlocality faraway from the source\, and
in particular increase their tolerance to particle losses. We critically
review their results and present a simple counterexample to it. We then in
troduce a class of hybrid quantum-classical models\, which we refer to as
"short-range quantum models". These models suitably capture the tradeoff b
etween short-range and long-range correlations in routed Bell experiments.
Using our definition\, we explore new nonlocal tests in which high-qualit
y short-range correlations lead to weakened conditions for long-range test
s. Although we do find improvements\, they are significantly smaller than
those claimed by CVP.\n\nhttps://events.perimeterinstitute.ca/event/38/con
tributions/595/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/38/contributions/595/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Causal-model approach to extended contextuality
DTSTART;VALUE=DATE-TIME:20230420T183000Z
DTEND;VALUE=DATE-TIME:20230420T190000Z
DTSTAMP;VALUE=DATE-TIME:20230608T105531Z
UID:indico-contribution-38-600@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Matt Jones (University of Colorado)\nThere has been
recent interest in extending the concept of contextuality to cases of dist
urbance or inconsistent connectedness. This talk will describe an approach
using probabilistic causal models\, which generalize the hidden-variables
models of Bell and Kochen & Specker\, following recent work by Cavalcanti
. I first prove an equivalence between three conditions on an arbitrary me
asurement system: (1) existence of a model minimizing all causal influence
s of context upon measurement outcomes\, (2) prohibition of a form of "hid
den" causal influence\, and (3) noncontextuality as defined in the Context
uality-by-Default (CbD) theory of Dzhafarov and Kujala. The no-hidden-infl
uence principle thus confers a physical interpretation to CbD-contextualit
y\, paralleling Bell's local causality and Kochen & Specker's classical em
beddability. I then extend this analysis to other causal graph topologies\
, showing that different graphs yield different notions of contextuality\,
but only the one corresponding to CbD agrees with traditional contextuali
ty when restricted to non-disturbing systems.\n\nhttps://events.perimeteri
nstitute.ca/event/38/contributions/600/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/38/contributions/600/
END:VEVENT
BEGIN:VEVENT
SUMMARY:SDP approaches for quantum polynomial optimization
DTSTART;VALUE=DATE-TIME:20230420T140000Z
DTEND;VALUE=DATE-TIME:20230420T143000Z
DTSTAMP;VALUE=DATE-TIME:20230608T105531Z
UID:indico-contribution-38-594@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Laurens Ligthart (University of Cologne)\n"Many rele
vant tasks in Quantum Information processing can be expressed as polynomia
l optimization problems over states and operators. In the earlier talk by
David\, we saw that this is also the case for certain (quantum) causal com
patibility and causal optimization problems.\nThis talk will focus on seve
ral closely related semidefinite programming (SDP) hierarchies that have r
ecently been shown to be complete for such polynomial optimization problem
s [arxiv:2110.14659\, 2212.11299\, 2301.12513]. We give a high-level overv
iew of the techniques and mathematics that are needed for proving such sta
tements. In particular\, we will see a version of a Quantum De Finetti the
orem\, as well as a sketch of a constructive proof of convergence for the
SDP hierarchies. Afterwards\, these results are linked back to the causal
compatibility problem to conclude that such SDP hierarchies are complete f
or a certain type of causal structures known as tree networks."\n\nhttps:/
/events.perimeterinstitute.ca/event/38/contributions/594/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/38/contributions/594/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Is causal optimization polynomial optimization?
DTSTART;VALUE=DATE-TIME:20230420T133000Z
DTEND;VALUE=DATE-TIME:20230420T140000Z
DTSTAMP;VALUE=DATE-TIME:20230608T105531Z
UID:indico-contribution-38-593@events.perimeterinstitute.ca
DESCRIPTION:Speakers: David Gross (University of Cologne)\n"Is there a co
mplete semi-definite programming hierarchy for quantum causal problems? We
divide the question into two parts. First: Can quantum causal problems be
expressed as polynomial optimization problems (this talk). Second: Can th
is class of polynomial optimizations be solved by means of SDPs (Laurens'
talk). The optimizations we consider here are ""polynomial"" in two ways.
They are over the unknown observable algebra of the hidden systems\, which
are specified by non-commutative polynomials in a set of generators. But
they also involve independence constraints\, which are commutative polynom
ials in the state. A hierarchy\nof such polynomial tests is complete if on
e can construct a quantum model for any observed distribution that passes
all of them. We've recently had some success in finding such constructions
\, but also ran into problems in the general case [1\, 2]. I give a high-l
evel presentation of the state of the play.\n\n[1] https://arxiv.org/abs/2
110.14659\n[2] https://arxiv.org/abs/2212.11299"\n\nhttps://events.perimet
erinstitute.ca/event/38/contributions/593/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/38/contributions/593/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Conditional Independence - Revisited
DTSTART;VALUE=DATE-TIME:20230419T140000Z
DTEND;VALUE=DATE-TIME:20230419T143000Z
DTSTAMP;VALUE=DATE-TIME:20230608T105531Z
UID:indico-contribution-38-588@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Patrick Forre (Universiteit van Amsterdam)\n"Many re
lationships in causality\, statistics or probability theory can be express
ed as conditional independence relations between the occurring random vari
ables. Since the invention of the notion of conditional independence one a
im was to be able to also express such relationship between random and non
-random variables\, like the parameters of a stochastic model\, the input
variables of a probabilistic program or intervention variables in a causal
model. Over time several different versions of such extended conditional
independence notion have been proposed\, each coming with their own advant
ages and disadvantages\, oftentimes limited to certain subclasses of rando
m variables like discrete variables or ones with densities.\nIn this talk
we present another such notion of conditional independence\, which can eas
ily be expressed in measure-theoretic generality and even in categorical p
robability. We will study its expressivity\, present its (convenient) prop
erties\, and relate it to other notions of conditional independence."\n\nh
ttps://events.perimeterinstitute.ca/event/38/contributions/588/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/38/contributions/588/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Towards standard imsets for maximal ancestral graphs
DTSTART;VALUE=DATE-TIME:20230417T160000Z
DTEND;VALUE=DATE-TIME:20230417T163000Z
DTSTAMP;VALUE=DATE-TIME:20230608T105531Z
UID:indico-contribution-38-577@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Robin Evans (University of Oxford)\n"Imsets\, intro
duced by Studený (see Studený\, 2005 for details)\, are an algebraic met
hod for representing conditional independence models. They have many attra
ctive properties when applied to such models\, and they are particularly n
ice when applied to directed acyclic graph (DAG) models. In particular\, t
he standard imset for a DAG is in one-to-one correspondence with the indep
endence model it induces\, and hence is a label for its Markov equivalence
class. We present a proposed extension to standard imsets for maximal anc
estral graph (MAG) models\, which have directed and bidirected edges\, usi
ng the parameterizing set representation of Hu and Evans (2020). By constr
uction\, our imset also represents the Markov equivalence class of the MAG
. \n\nWe show that for many such graphs our proposed imset defines the mod
el\, though there is a subclass of graphs for which the representation doe
s not. We prove that it does work for MAGs that include models with no adj
acent bidirected edges\, as well as for a large class of purely bidirected
models. If there is time\, we will also discuss applications of imsets to
structure learning in MAGs. \n\nThis is joint work with Zhongyi Hu (Oxfor
d).\n\nReferences \n\nZ. Hu and R.J. Evans\, Faster algorithms for Markov
equivalence\, In Proceedings for the 36th Conference on Uncertainty in Art
ificial Intelligence (UAI-2020)\, 2020. \n\nM. Studený\, Probabilistic Co
nditional Independence Structures\, Springer-Verlag\, 2005."\n\nhttps://ev
ents.perimeterinstitute.ca/event/38/contributions/577/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/38/contributions/577/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Panel Discussion
DTSTART;VALUE=DATE-TIME:20230421T180000Z
DTEND;VALUE=DATE-TIME:20230421T190000Z
DTSTAMP;VALUE=DATE-TIME:20230608T105531Z
UID:indico-contribution-38-598@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Sonia Markes (University of Toronto)\nhttps://events
.perimeterinstitute.ca/event/38/contributions/598/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/38/contributions/598/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Some applications of Causal Inference in the real world
DTSTART;VALUE=DATE-TIME:20230421T140000Z
DTEND;VALUE=DATE-TIME:20230421T143000Z
DTSTAMP;VALUE=DATE-TIME:20230608T105531Z
UID:indico-contribution-38-597@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Ciaran Gilligan-Lee (Spotify and University College
London)\nCausal reasoning is vital for effective reasoning in many domains
\, from healthcare to economics. In medical diagnosis\, for example\, a do
ctor aims to explain a patient’s symptoms by determining the diseases ca
using them. This is because causal relations\, unlike correlations\, allow
one to reason about the consequences of possible treatments and to answer
counterfactual queries. In this talk I will present two recent causal inf
erence projects done with my collaborators deriving new algorithms to solv
e problems that arise when applying causal inference in the real world.\n\
nhttps://events.perimeterinstitute.ca/event/38/contributions/597/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/38/contributions/597/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Half-Trek Criterion for Identifiability of Latent Variable Models
DTSTART;VALUE=DATE-TIME:20230421T133000Z
DTEND;VALUE=DATE-TIME:20230421T140000Z
DTSTAMP;VALUE=DATE-TIME:20230608T105531Z
UID:indico-contribution-38-596@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Mathias Drton (Technical University Munich)\n"Linear
structural equation models relate random variables of interest via a line
ar equation system that features stochastic noise. The models are natural
ly represented by directed graphs whose edges indicate non-zero coefficien
ts in the linear equations. In this talk I will report on progress on com
binatorial conditions for parameter identifiability in models with latent
(i.e.\, unobserved) variables. Identifiability holds if the coefficients
associated with the edges of the graph can be uniquely recovered from the
covariance matrix they define.\n\nPaper: \nhttps://doi.org/10.1214/22-AOS
2221 or\nhttps://arxiv.org/abs/2201.04457"\n\nhttps://events.perimeterinst
itute.ca/event/38/contributions/596/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/38/contributions/596/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Quantum entropic causal inference
DTSTART;VALUE=DATE-TIME:20230419T200000Z
DTEND;VALUE=DATE-TIME:20230419T203000Z
DTSTAMP;VALUE=DATE-TIME:20230608T105531Z
UID:indico-contribution-38-591@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Vaneet Aggarwal (Purdue University)\, Zubin Jacob (P
urdue University)\nThe class of problems in causal inference which seeks t
o isolate causal correlations solely from observational data even without
interventions has come to the forefront of machine learning\, neuroscience
and social sciences. As new large scale quantum systems go online\, it op
ens interesting questions of whether a quantum framework exists on isolati
ng causal correlations without any interventions on a quantum system. We p
ut forth a theoretical framework for merging quantum information science a
nd causal inference by exploiting entropic principles. At the root of our
approach is the proposition that the true causal direction minimizes the e
ntropy of exogenous variables in a non-local hidden variable theory. The p
roposed framework uses a quantum causal structural equation model to build
the connection between two fields: entropic causal inference and the quan
tum marginal problem. First\, inspired by the definition of geometric quan
tum discord\, we fill the gap between classical and quantum conditional de
nsity matrices to define quantum causal models. Subsequently\, using a gre
edy approach\, we develop a scalable algorithm for quantum entropic causal
inference unifying classical and quantum causality in a principled way. W
e apply our proposed algorithm to an experimentally relevant scenario of i
dentifying the subsystem impacted by noise starting from an entangled stat
e. This successful inference on a synthetic quantum dataset can have pract
ical applications in identifying originators of malicious activity on futu
re multi-node quantum networks as well as quantum error correction. As qua
ntum datasets and systems grow in complexity\, our framework can play a fo
undational role in bringing observational causal inference from the classi
cal to the quantum domain.\n\nhttps://events.perimeterinstitute.ca/event/3
8/contributions/591/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/38/contributions/591/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Bounding counterfactual distributions in discrete structural causa
l models
DTSTART;VALUE=DATE-TIME:20230419T193000Z
DTEND;VALUE=DATE-TIME:20230419T200000Z
DTSTAMP;VALUE=DATE-TIME:20230608T105531Z
UID:indico-contribution-38-590@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Jin Tian (Iowa State University)\nWe investigate the
problem of bounding counterfactual queries from an arbitrary collection o
f observational and experimental distributions and qualitative knowledge a
bout the underlying data-generating model represented in the form of a cau
sal diagram. We show that all counterfactual distributions in an arbitrary
structural causal model (SCM) with finite discrete endogenous variables c
ould be generated by a family of SCMs with the same causal diagram where u
nobserved (exogenous) variables are discrete with a finite domain. Utilizi
ng this family of SCMs\, we translate the problem of bounding counterfactu
als into that of polynomial programming whose solution provides optimal bo
unds for the counterfactual query.\n\nhttps://events.perimeterinstitute.ca
/event/38/contributions/590/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/38/contributions/590/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A quantum tale of causes and effects
DTSTART;VALUE=DATE-TIME:20230419T180000Z
DTEND;VALUE=DATE-TIME:20230419T190000Z
DTSTAMP;VALUE=DATE-TIME:20230608T105531Z
UID:indico-contribution-38-589@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Rafael Chaves (Federal University of Rio Grande do
Norte)\nExplaining the natural world through cause-and-effect relations is
the fundamental principle of science. Although a classical theory of caus
ality has been recently introduced\, enabling us to model causation across
diverse research fields\, it is crucial to examine which aspects of it re
quire modification or abandonment to also comprehend causality in the quan
tum world. To address this question\, we will investigate paradigmatic sce
narios\, including the double slit\, Bell's theorem and generalizations to
quantum networks\, also exploring recent experimental advancements.\n\nht
tps://events.perimeterinstitute.ca/event/38/contributions/589/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/38/contributions/589/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A Hierarchy of Multi-Party Nonlocal Effects
DTSTART;VALUE=DATE-TIME:20230419T133000Z
DTEND;VALUE=DATE-TIME:20230419T140000Z
DTSTAMP;VALUE=DATE-TIME:20230608T105531Z
UID:indico-contribution-38-587@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Peter Bierhorst (University of New Orleans)\nAccordi
ng to recent new definitions\, a multi-party behavior is genuinely multipa
rtite nonlocal (GMNL) if it cannot be modeled by measurements on an underl
ying network of bipartite-only nonlocal resources\, possibly supplemented
with local (classical) resources shared by all parties. Three experimental
results published in 2022 provide initial evidence\, subject to postselec
tion-related assumptions\, for the existence of behaviors meeting these de
finitions of GMNL. The new definitions of GMNL differ on whether to allow
entangled measurements upon\, and/or superquantum behaviors among\, the un
derlying bipartite resources when classifying behaviors asonly bipartit
e nonlocal. I will discuss the interrelationships of these choices in thre
e-party quantum networks\, and present a behavior in the simplest nontrivi
al multi-partite measurement scenario (3 parties\, 2 measurement settings\
, and 2 outcomes) that (A) cannot be simulated in a bipartite network proh
ibiting both entangled measurements and superquantum resources\, (B) can b
e simulated with bipartite-only quantum states allowing for an entangled q
uantum measurement (indicating an approach to device independent certifica
tion of entangled measurements with fewer settings than in previous protoc
ols)\, and surprisingly (C) can be simulated with bipartite-only superquan
tum states (Popescu-Rohrlich boxes) while maintaining a prohibition on ent
angled measurements. It turns out that other behaviors previously studied
as device-independent witnesses of entangled measurements can also be simu
lated in the manner of (C)\, posing a challenge to a theory-independent un
derstanding of entangled measurements as an observable phenomenon distinct
from bipartite nonlocality.\n\nhttps://events.perimeterinstitute.ca/event
/38/contributions/587/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/38/contributions/587/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Causal Discovery via Common Entropy
DTSTART;VALUE=DATE-TIME:20230418T180000Z
DTEND;VALUE=DATE-TIME:20230418T183000Z
DTSTAMP;VALUE=DATE-TIME:20230608T105531Z
UID:indico-contribution-38-585@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Murat Kocaoglu (Purdue University)\nDistinguishing c
ausation from correlation from observational data requires assumptions. We
consider the setting where the unobserved confounder between two observed
variables is simple in an information-theoretic sense\, captured by its e
ntropy. When the observed dependence is not due to causation\, there exist
s a small-entropy variable that can make the observed variables conditiona
lly independent. The smallest such entropy is known as common entropy in i
nformation theory. We extend this notion to Renyi common entropy by minimi
zing the Renyi entropy of the latent variable. We establish identifiabilit
y results with Renyi-0 common entropy\, and a special case of (binary) Ren
yi-1 common entropy. To efficiently compute common entropy\, we propose an
iterative algorithm that can be used to discover the trade-off between th
e entropy of the latent variable and the conditional mutual information of
the observed variables. We show that our algorithm can be used to disting
uish causation from correlation in such simple two-variable systems. Addit
ionally\, we show that common entropy can be used to improve constraint-ba
sed methods such as the PC algorithm in the small-sample regime\, where su
ch methods are known to struggle. We propose modifying these constraint-ba
sed methods to assess if a separating set found by these algorithms is val
id using common entropy. We finally evaluate our algorithms on synthetic a
nd real data to establish their performance.\n\nhttps://events.perimeterin
stitute.ca/event/38/contributions/585/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/38/contributions/585/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Causal Scenarios: the Interesting\, the Boring and the Elusive
DTSTART;VALUE=DATE-TIME:20230418T150000Z
DTEND;VALUE=DATE-TIME:20230418T153000Z
DTSTAMP;VALUE=DATE-TIME:20230608T105531Z
UID:indico-contribution-38-584@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Matthew Pusey (University of York)\nI will sketch t
he current state of play with classifying causal scenarios (aka DAGs with
latent variables). Some are interesting: the classical correlations are co
nstrained by non-trivial inequalities such as Bell’s. Some are boring: t
he classical correlations are constrained only by observable conditional i
ndependencies. Some we still don’t know. Along the way I will mention jo
int work with Joe Henson\, Ray Lal\, Shashaank Khanna\, Marina Ansanelli a
nd Elie Wolfe\, and disjoint work by Robin Evans.\n\nhttps://events.perime
terinstitute.ca/event/38/contributions/584/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/38/contributions/584/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Separation of quantum\, spatial quantum and approximate quantum co
rrelations
DTSTART;VALUE=DATE-TIME:20230418T140000Z
DTEND;VALUE=DATE-TIME:20230418T143000Z
DTSTAMP;VALUE=DATE-TIME:20230608T105531Z
UID:indico-contribution-38-583@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Salman Beigi (Institute for Research in Fundamental
Sciences)\nQuantum nonlocal correlations are generated by implementation o
f local quantum measurements on spatially separated quantum subsystems. De
pending on the underlying mathematical model and the dimension of the unde
rlying Hilbert spaces\, various notions of sets of quantum correlations ca
n be defined. This talk is devoted to the separations of some of these set
s via simple ideas in quantum information theory\, namely self-testing and
entanglement embezzlement.\n\nhttps://events.perimeterinstitute.ca/event/
38/contributions/583/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/38/contributions/583/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Communication Genuine Multipartite Nonlocality as a benchmark for
large nonclassicality
DTSTART;VALUE=DATE-TIME:20230418T133000Z
DTEND;VALUE=DATE-TIME:20230418T140000Z
DTSTAMP;VALUE=DATE-TIME:20230608T105531Z
UID:indico-contribution-38-582@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Marc-Olivier Renou (Institute of Photonic Sciences)
\n"Quantum computing requires the ability to manipulate large nonclassical
quantum systems. As we are far from any useful quantum computing advantag
e\, certifying this ability is an important benchmark to assess progress t
oward this goal. This can be done using the nonlocal nature of quantum cor
relations\, which allows to certify a non-trusted experimental apparatus f
rom its input/output behaviour in a device independent way. It first requi
res to introduce the concept of Genuine Multipartite Nonlocality (GMNL) of
size n\, which designate systems which nonlocality cannot be understood a
n obtained from many states composed of n − 1 (or less) constituents.\n\
nThe first historical definition of GMNL\, proposed by Svetlichny\, is ill
-defined when used to assess the large nonclassical nature of quantum syst
ems\, as it predicts that maximal GMNL states can be obtain from bipartite
sources only. A more appropriate re-definition of that concept\, called L
OSR-GMNL\, was proposed recently [arXiv:2105.09381]. However\, it is not s
atisfactory in all experimental situations\, as it cannot (by design) capt
ure potential communications between the systems which could occur in some
realistic experimental systems (e.g.\, many-body systems) – which Svetl
ichny definition captures in a naïve way.\n\nIn this talk\, I will propos
e a new alternative re-definition solving this issue\, called Communicatio
n-Genuine Multipartite Nonlocality of length t (C-GMNL). It is based on a
model inspired from synchronous distributed computing\, that involves t co
mmunications steps along a graph.\n\nI will show that (i) the GHZ state is
maximally nonlocal according to this C-GMNL definition\, (ii) the cluster
state is trivial in this C-GMNL definition but that (iii) the cluster sta
te is maximally difficult in the LOSR-GMNL definition. Hence\, some compli
cated LOSR-GMNL states become trivial when a small amount of communication
is allowed.\n\nBased on a joint work in preparation with Xavier Coiteux-R
oy\, Owidiusz Makuta\, Fionnuala Curran\, Remigiusz Augusiak."\n\nhttps://
events.perimeterinstitute.ca/event/38/contributions/582/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/38/contributions/582/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Entropic Inequality Constraints from e-separation Relations in Dir
ected Acyclic Graphs with Hidden Variables
DTSTART;VALUE=DATE-TIME:20230417T203000Z
DTEND;VALUE=DATE-TIME:20230417T210000Z
DTSTAMP;VALUE=DATE-TIME:20230608T105531Z
UID:indico-contribution-38-581@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Beata Zjawin (Gdansk University)\nWhen some variable
s in a directed acyclic graph (DAG) are hidden\, a notoriously complicated
set of constraints on the distribution of observed variables is implied.
In this talk\, we present inequality constraints implied by graphical crit
eria in hidden variable DAGs. The constraints can intuitively be understoo
d to follow from the fact that the capacity of variables along a causal pa
thway to convey information is restricted by their entropy. For DAGs that
exhibit e-separation relations\, we present entropic inequality constraint
s and we show how they can be used to learn about the true causal model fr
om an observed data distribution (arXiv:2107.07087).\n\nhttps://events.per
imeterinstitute.ca/event/38/contributions/581/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/38/contributions/581/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Observational Equivalences Between Causal Structures with Latent V
ariables
DTSTART;VALUE=DATE-TIME:20230417T200000Z
DTEND;VALUE=DATE-TIME:20230417T203000Z
DTSTAMP;VALUE=DATE-TIME:20230608T105531Z
UID:indico-contribution-38-580@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Marina Maciel Ansanelli (Perimeter Institute)\n"If
one only performs experiments involving passive observations\, in general
there are multiple causal structures that can explain the same set of dist
ributions over the observed variables. In this case\, we say that these ca
usal structures are observationally equivalent. In this work\, we explore
all the known techniques for proving observational equivalence or inequiva
lence\, as well as some original ones. \nEven if the existing rules are no
t enough to achieve the full classification of the causal structures with
four observed variables\, our results get close to such classification and
show that admitting inequality constraints is a generic feature among str
uctures with four observed variables."\n\nhttps://events.perimeterinstitut
e.ca/event/38/contributions/580/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/38/contributions/580/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Correlations from joint measurements in boxworld and applications
to information processing
DTSTART;VALUE=DATE-TIME:20230417T193000Z
DTEND;VALUE=DATE-TIME:20230417T200000Z
DTSTAMP;VALUE=DATE-TIME:20230608T105531Z
UID:indico-contribution-38-579@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Mirjam Weilenmann (Institute for Quantum Optics and
Quantum Information)\nQuantum measurements have been a central topic of r
esearch in quantum theory for many years. In the context of causal structu
res and communication over networks\, we are often particularly interested
in local measurements of subsystems of a multi-partite system and classic
al processing of their inputs and outcomes. Formally\, this processing can
often be described by means of maps that are known as wirings. These wiri
ngs are furthermore interesting for the analysis of generalized probabilis
tic theories\, as they are shared by all of them. In this work\, we explic
itly characterise all possible mulitpartite measurements in the generalise
d probabilistic theory box-world for various numbers of parties n with sys
tems characterised by n_i fiducial measurements (which can be thought of a
s inputs here) and n_o outcomes\, for small n\, n_i\, n_o. This includes
all n-party n_i-input\, n_o-outcome wirings. For n > 2\, we further classi
fy these measurements into three classes: wirings\, deterministic non-wiri
ng type and non-deterministic non-wiring type measurements. We explore adv
antages of these different types of measurements over previous protocols i
n the context of non-locality distillation and state-distingishability. We
further find examples of non-locality without entanglement (contrary to p
revious claims) and a relation of these measurements to classical process
matrices.\n\nhttps://events.perimeterinstitute.ca/event/38/contributions/5
79/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/38/contributions/579/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tutorial 2
DTSTART;VALUE=DATE-TIME:20230417T180000Z
DTEND;VALUE=DATE-TIME:20230417T190000Z
DTSTAMP;VALUE=DATE-TIME:20230608T105531Z
UID:indico-contribution-38-578@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Ilya Shpitser (Johns Hopkins University)\nhttps://ev
ents.perimeterinstitute.ca/event/38/contributions/578/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/38/contributions/578/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Graphical models: fundamentals\, origins\, and beyond
DTSTART;VALUE=DATE-TIME:20230417T153000Z
DTEND;VALUE=DATE-TIME:20230417T160000Z
DTSTAMP;VALUE=DATE-TIME:20230608T105531Z
UID:indico-contribution-38-576@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Steffen Lauritzen (University of Copenhagen)\nThe le
cture will give a brief introduction to graphical models\, their origins i
n Physics\, Genetics\, and Econometrics\, their modern usages\, and some f
uture perspectives.\n\nhttps://events.perimeterinstitute.ca/event/38/contr
ibutions/576/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/38/contributions/576/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tutorial 1
DTSTART;VALUE=DATE-TIME:20230417T140000Z
DTEND;VALUE=DATE-TIME:20230417T150000Z
DTSTAMP;VALUE=DATE-TIME:20230608T105531Z
UID:indico-contribution-38-575@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Robert Spekkens (Perimeter Institute)\nhttps://event
s.perimeterinstitute.ca/event/38/contributions/575/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/38/contributions/575/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Welcome and Opening Remarks
DTSTART;VALUE=DATE-TIME:20230417T133000Z
DTEND;VALUE=DATE-TIME:20230417T140000Z
DTSTAMP;VALUE=DATE-TIME:20230608T105531Z
UID:indico-contribution-38-574@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Elie Wolfe (Perimeter Institute)\nhttps://events.per
imeterinstitute.ca/event/38/contributions/574/
LOCATION:Perimeter Institute for Theoretical Physics PI/4-405 - Bob Room
URL:https://events.perimeterinstitute.ca/event/38/contributions/574/
END:VEVENT
END:VCALENDAR