June 2 Fundamental Physics from
Galaxy Surveys
Speaker: Mikhail Ivanov,
Institute for Advanced Study

The distribution of galaxies on
large scales is a sensitive
probe of cosmological physics.
In particular, the structure of
this distribution depends on
properties of dark matter and
the dynamics of the early
universe. Understanding this
dependence, however, is a
challenging task because the
observed galaxy distribution is
modulated by a variety of
non-linear effects. I will
present innovative theoretical
tools that have allowed for a
systematic analytic description
of these effects. These tools
play a central role in a new
program of extracting
cosmological information from
galaxy surveys. I will share
some results of this program
from my independent analysis of
the public data from the Baryon
acoustic Oscillation
Spectroscopic Survey. These
results include the measurement
of the Hubble constant as well
as constraints on new physics
and the early Universe. Finally,
I will discuss the main
challenges of this program and
possible synergies with machine
learning.
Watch the lecture.

June 9 Accelerating
first-principles calculations
of the structure of matter
with machine learning
Speaker: Phiala Shanahan, MIT

Our
understanding of the structure
of matter, encapsulated in the
Standard Model of particle
physics, is that protons,
neutrons, and nuclei emerge
dynamically from the
interactions of underlying quark
and gluon degrees of freedom. I
will describe recent progress in
first-principles studies of the
Standard Model, highlighting
first direct studies of nuclear
structure and interactions,
including calculations relevant
to the interpretation of dark
matter direct detection
experiments. Motivated by the
extreme computational demands of
such studies at the nuclear
scale, I will discuss
opportunities for acceleration
through provably-exact machine
learning algorithms.
Watch the lecture.

June 16 Machine learning for
biological sequence design
with therapeutic applications
Speaker: Lucy Colwell, Cambridge
University

Prediction
of protein function from
sequence is a central challenge
that allows us to discover new
proteins with specific
functional properties.
Experimental and computational
labels can be used to train and
validate machine learning models
that predict protein function
directly from sequence. I will
present deep learning models
that accurately predict the
presence and location of
functional domains within
protein sequences, adding
hundreds of millions of
annotations to public databases.
Furthermore, experimental
breakthroughs enable data on the
relationship between sequence
and function to be rapidly
acquired. However, the cost and
latency of wet-lab experiments
require methods that find good
sequences in few experimental
rounds, where each round
contains large batches of
sequence designs. In this
setting, I will discuss
model-based optimization
approaches that take advantage
of sample inefficient methods to
find diverse sequence candidates
for experimental evaluation. The
potential of this approach is
illustrated through the design
and experimental validation of
proteins and peptides for
therapeutic applications.
Watch the lecture.

June 23 LIGO: a 1/10 scale model of
Cosmic Explorer
Speaker: David Shoemaker,
MIT Kavli Institute

The field of
gravitational-wave astronomy has
demonstrated its ability to
provide insights into
gravitation in the extremes of
nature, as well as its ability
to complement photon and
particle astronomy and
astrophysics. With roughly 100
events since the first
observation in 2015, the
approach to the instrumentation
and its ability to deliver more
science when upgraded even
incrementally is demonstrated.
The field is
now formulating observatory
concepts for a significant step
in sensitivity – ten times that
of the current instruments. This
will bring to the order of 103
more sources into reach, in
addition to improving the
resolution for nearby sources
and increasing the sensitive
range in frequency and thus
variety of sources.
We will
describe the US vision for the
next generation
gravitational-wave observatory,
Cosmic Explorer, and call on the
experience to date with LIGO to
provide a sense of the
feasibility and the path to
realization for this major
undertaking.
Watch the lecture.

June 30 How Materials Can
Learn How to Function
Speaker: Andrea Liu,
University of Pennsylvania

Artificial
neural networks learn via
optimization where a loss
function is minimized by a
computer to achieve the desired
result. But physical networks,
such as mechanical spring
networks or flow networks, have
no attached processors to
perform the optimization, so
they cannot minimize such a loss
function. What such systems do
automatically minimize is their
elastic energy (mechanical
networks) or the dissipated
power (flow network). I will
describe how these natural
physical processes can be
harnessed to teach systems how
to perform machine learning
tasks such as classification, as
well as functions inspired by
biology. For example, the
ability of proteins (e.g.
hemoglobin) to change their
conformations upon binding of an
atom (oxygen) or molecule, or
the ability of the brain’s
vascular network to send
enhanced blood flow and oxygen
to specific areas of the brain
associated with a given task.
This learning strategy has
recently been implemented in
electrical circuits.

July 7 New Rules: Quantum
Circuits, Cellular
Automata, Complexity and
Chaos
Speaker: Austen Lamacraft,
University of Cambridge

Many of you
will have played with cellular
automata such as Conway's Game
of Life. These are model systems
in which complex and chaotic
behaviors emerge from simple
dynamical rules.

Motivated by quantum
computation, physicists have in
recent years begun to study
quantum circuits, which are in
some way a quantum analogue of
cellular automata. In this talk,
I'll discuss some of the
similarities and differences
between these two classes of
systems, and what they can teach
us about classical and quantum
dynamics more generally.

July 14 Monitoring Quantum
Dynamics
Speaker: Matthew P.A.
Fisher, University of
California Santa Barbara

When a
quantum system is coupled
to a dissipative
environment an initially
pure state becomes rapidly
mixed as information is
lost, and classical
behavior invariably
follows. Recently, another
type of open system
dynamics has been
explored, when a quantum
system is continuously
\mon-
itored" by an observer,
making a sequence of
measurements, and a pure
quantum state remains
pure. The resulting
quantum trajectories
constitute an ensemble of
pure states, which can (in
principle) be
experimentally accessed in
digital quantum
simulators. In the
many-body context, these
quantum trajectories can
have a rich entanglement
structure, exhibiting -
for example - dynamical
phase transitions between
volume law and area law
entanglement, and between
phases with or without
symmetry breaking and/or
topological order. For
mixed initial density
matrices, monitoring can
lead to a plethora of
purication transitions,
and reveals underlying
connections with quantum
encoding. Accessing such
physics in the lab is
challenged by the need for
post-selection, which
might be circumnavigated
by decoding using active
error correction. In this
talk I will try to give an
overview of some topics in
such monitored quantum
dynamics.

July 21 Using the Solar Wind as a
Natural Laboratory to Study
Space Plasma Turbulence
Speaker: Kristopher Klein,
University of Arizona

Turbulent
magnetic and velocity
fluctuations are responsible for
the transport of mass, momentum,
and energy in a variety of
plasma systems throughout the
solar system and universe. In
this talk, I discuss recent
advances in our understanding of
the role that turbulence plays
in weakly collisional plasma
systems drawn from in situ
measurements of electromagnetic
fields and charged particle
velocity distributions from the
Sun's extended atmosphere, made
over the last half-century,
including most recently by
Parker Solar Probe and MMS.
Changes in the nature of the
turbulence with varying distance
from the Sun's surface, as well
as a function of key
dimensionless system parameters,
are discussed. We conclude with
open questions regarding the
three-dimensional structure and
dynamics of plasma turbulence
that will be addressed over this
next decade by multi-point,
multi-scale missions such as the
recently selected HelioSwarm
Observatory.

July 28 Probing Dense Matter with
Neutron Star Mergers
Speaker: Carolyn Raithel, Institute
for Advanced Study

Neutron stars provide a unique
laboratory for studying the properties
and interactions of ultra-dense
matter. With the recent advent of
gravitational wave astronomy, we have
gained a new window into the extreme
conditions that characterize the
neutron star interior. In this
talk, I will discuss what we have
learned so far about the dense-matter
equation of state (EOS) from the first
observations of inspiraling neutron
stars. I will then present
a set of numerical merger
simulations that use a
phenomenological framework to study
new parts of the EOS parameter space.
Using these simulations, I
will discuss the additional
physics that we might be able to probe
with a future measurement of
post-merger gravitational waves, which
are emitted by the hot and massive
neutron star remnant that forms
following the merger. The conditions
of the post-merger phase differ
significantly from the inspiral,
providing the possibility of
constraining the EOS across a range of
densities and temperatures.

August 4 Strong Electronic
Correlations, Topological Phases
and Unconventional
Superconductivity in Magical
Flatbands
Speaker: Ali Yazdani, Princeton
University

One the exciting new material
platforms for exploring properties
of highly interacting electrons is
the newly discovered bilayers of
graphene twisted to a magic angle. I
will describe how using high
resolution experiments with the
scanning tunneling microscope, we
can explore the remarkably complex
physics of this novel system. I will
show how we characterize strong
electronic correlations, how
correlations in this system created
novel topological phases and
describe how we probe the nature of
superconductivity that emerges in
this material in the presence of
strong electronic correlation. I
will show the remarkable similarity
in the properties of the
superconducting phase in this
material and that which occurs in
high-Tc cuprate superconductors.

August 11 Exotic Superconductivity in
Graphene Multilayers
Speaker: Erez Berg, Weizmann
Institute of Science

Recently,
graphene multilayers have
emerged as a rich platform to
study quantum many-body
physics. I will describe
recent experiments on a stack
of three layers of graphene,
where superconductivity was
recently discovered at the
boundary between states with
different broken symmetries.
Experiments hint to an
unconventional mechanism for
superconductivity, where
counterintuitively, the
binding of electrons into
pairs originates from the
repulsive Coulomb interaction
between them. Even more
interestingly, one of the
superconducting phases in
trilayer graphene seems to be
an unusual fully spin
polarized triplet state. The
topology of its order
parameter space, that
intertwines the phase of the
superconducting condensate
with the spin polarization,
can lead to unusual phenomena,
such as anomalous supercurrent
dissipation and a
fractional-period ac
Josephson effect.

August 18 The Central Dogma of
Black Holes
Speaker: Ahmed Almheiri,
Institute for Advanced Study

Research
over the past few decades has
uncovered an intimate
connection between gravity and
quantum information and has
led to surprising conclusions
about the nature of black
holes. In particular, it
supports the so-called central
dogma of black holes, the idea
that a black hole behaves like
a quantum system with a finite
number of degrees of freedom
that evolves under unitary but
chaotic time evolution. I will
motivate this picture of black
holes and discuss how it
follows from the path integral
of gravity. Furthermore, I
will highlight its
implications on the
information paradox regarding
the fate of information that
falls into a black hole, and
on the more recent firewall
paradox that puts into
question the very existence of
the black hole interior. We
will see that progress on
these questions is only
possible because the path
integral of gravity implements
a quantum error correcting
code.

August 25 Looking Beyond the Dark
Matter in Axion Haloscopes
Speaker: Nicholas Rodd, CERN

The coming decade
will bring dramatic improvement
in the axion dark-matter program
as new experimental designs move
beyond the proof of principle
stage. In this talk I will
outline two signals beyond dark
matter that these instruments
could discover. The first is a
population of relativistic
axions that were produced in the
early universe and persist as a
residual Cosmic axion Background
(CaB). The second is
high-frequency gravitational
waves; I will outline how
exploiting an analogy between
axion and gravitational-wave
electrodynamics allows for axion
haloscopes to be converted into
gravitational-wave telescopes.

September 1 Electroweak Baryogenesis
and the LHC
Speaker: Marcela Carena,
Fermilab

With Run 3 of the LHC starting
this summer, it is timely to
take a fresh look at the
question of whether the
electroweak phase transition
could have been the source of
the observed matter-antimatter
asymmetry of our universe. Such
a process, known as electroweak
baryogenesis, requires the
existence of new particles
related to the Higgs boson, new
sources of CP violation, and
possibly new forces, all
manifesting during the
electroweak phase transition in
the early universe. I will
discuss three examples of
plausible scenarios, two focused
on the problem of preserving an
asymmetry once created, and the
third exhibiting a new mechanism
where the source of both CP
violation and the resulting
asymmetry comes from the dark
matter sector.

September 8 Anderson Transitions and
(Lost) Conformal Invariance
Speaker: Ilya Gruzberg, Ohio State
University

Anderson
transitions (ATs) between metals
and insulators or between
topologically distinct
insulators, share common
features with conventional
second-order phase transitions,
such as the critical point of
the Ising model for a magnet.
However, ATs also exhibit many
unusual features including the
multifractal scaling of the
critical wave functions.
Conventional critical points
possess conformal invariance
which constrain their properties
to the extent that they can be
obtained exactly in two
dimensions and to very high
precision in three dimensions.
Until recently, researchers
assumed that Anderson
transitions also possess
conformal invariance and can be
described by conformal field
theories (CFTs). I will review
recent progress in understanding
the relation between conformal
invariance and multifractal wave
functions. The emerging picture
puts serious doubt on the
ability of CFTs to properly
describe multifractality at ATs
in both two and three
dimensions.

September 15 QFT Aspects of Symmetry
Speaker: Ken Intriligator,
University of California San
Diego

Everything in the
Universe, including the photons that
we see and the quarks and electrons
in our bodies, are actually ripples
of quantum fields. Quantum field
theory (QFT) is the underlying
framework and examples include the
most precisely tested theory in
science, and also theories that
remain full of mysteries. QFT
also describes condensed matter
systems, connects (e.g. via AdS/CFT)
to string theory and quantum
gravity, describes inflationary
cosmology, and has fruitful
interconnections with
mathematics. Symmetry has deep
and powerful realizations and
implications throughout physics, and
this is especially so for the study
of QFT and its renormalization group
flows (zooming out). Topological
QFTs (TQFTs) have been under intense
study, including in the context of
condensed matter systems and also
mathematics, and also play roles in
non-topological QFTs. There
has been great recent synergy and
progress in generalized notions of
symmetries and applications to QFT;
our current Aspen workshop is
devoted to these topics. I will try
to provide an accessible,
colloquium-level introduction to
aspects of symmetries and QFT, both
old and new.