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Seminars
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Seminars
will be held in room S-141 in the Physics and
Astronomy Department building on Mondays at 4:00 PM, unless noted
otherwise. When necessary, virtual seminar
Zoom login instructions will be sent out via
email.
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Spring/Summer
2024
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March
18, 2024
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Dr.
Thomas Pattard
Editor,
Physical Review
A
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How
(not) to get your
paper published in a
physics journal
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(Host:
Jesús Pérez Ríos)
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Have
you done some
amazing
research, but
are unsure how
to communicate
the results?
Have you ever
wondered how the
process of
scientific
publishing and
peer review
works, and what
goes on in the
mind of an
editor (or if
they even have
one)? In this
talk, I will try
to give some
insight into the
process of
publishing in a
scientific
journal from the
perspective of
an editor. After
a very brief
introduction to
the world of
physics
publishing, I
will discuss how
to write a
scientific
paper, and what
to keep in mind
while doing so.
In the last part
of the talk, I
will give a
short overview
of the peer
review process
and the workflow
associated with
the
consideration of
a typical
manuscript, and
give some
pointers on how
to successfully
navigate the
process as an
author.
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April
5, 2024, 12:00 PM
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Prof.
Alexander
Lvovsky
Department of
Physics,
Oxford
University
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Optical
neural networks for
faster AI and
superresolution
imaging
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(Host:
Eden
Figueroa)
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Although
machine intelligence
is taking over the
world, its current
digital electronic
platform is very
inefficient in terms
of energy
consumption.
Switching to
analogue
computation, which
function more like
human brains than
digital computers,
will allow enhancing
the energy
efficiency by
several orders of
magnitude. Optics
presents a
particularly
promising platform
for analogue AI;
however, significant
challenges –
particularly in the
domain of neural
network training –
must be overcome
before it can
compete with its
digital counterpart.
A likely upcoming
range of
applications of
optical neuron
networks is in
computer vision, as
they will allow
eliminating the
bottleneck
associated with
back-and-forth
conversion of data
between optical and
electronic formats.
A further benefit of
optical processing
is enhancing the
quality of imaging.
For example, it
allows reaching the
quantum frontier of
imaging resolution
beyond Rayleigh’s
diffractive limit
which applies to
most of the modern
classical imaging
technology.
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April
8, 2024
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Dr.
Angela Pizzuto
Raytheon
Technologies
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Linear
and Nonlinear
Terahertz Near-Field
Microscopy for
Characterizing
Electronic Systems
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(Host:
Harold
Metcalf)
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Terahertz
scattering scanning
near field optical
microscopy (THz
s-SNOM) has become
an active research
topic for its
effectiveness in
characterizing
electronic behavior
in many materials
with nanoscale
resolution.
Motivated by a
desire to understand
the current
techniques more
deeply and to expand
upon them, here we
present novel
methods for
characterizing
metals and
semiconductors with
THz s-SNOM.
First, we
demonstrate the
first “nonlocal”
near-field optical
pump-terahertz probe
experiments, in
which we photoexcite
bulk undoped GaAs
and use a THz probe
pulse to observe the
change in reflection
at an area laterally
displaced from our
pump. We demonstrate
that this technique
can be used to
reveal anisotropy in
a sample by
highlighting
directions of
preferred carrier
motion. Next, we
expand this
technique to
nonlocal laser
terahertz emission
nanoscopy (LTEN), in
which we detect THz
emission from bulk
InAs at a location
displaced from our
pump area. We
determine that both
techniques can
reveal properties
related to carrier
motion, but the
latter can also
illustrate
mechanisms of THz
generation which are
poorly understood in
certain materials.
Finally, we
demonstrate the
first instance of
blue light LTEN. We
show that inducing
THz emission in
semiconductors via
high-energy pumping
can reveal
properties of charge
carriers in higher
bands not observable
with conventional
near-infrared
pumping. We create
the first near-field
THz emission image
of bulk Si and
provide a novel
framework for
correlating the
emission strength to
the Si doping
profile.
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April
15, 2024
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Prof.
David J.
Wineland
Nobel
Laureate,
Physics (2012)
University of
Oregon
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Atomic
Clocks
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(Host:
Harold
Metcalf)
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April
22, 2024
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Debadarshini
Mishra
UConn, Berrah
Lab
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Imaging
time-resolved dynamics
in molecular systems
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(Host:
Tom
Weinacht)
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Imaging
electronic and
molecular dynamics
at the attosecond
and femtosecond
timescales is
crucial for
understanding the
mechanisms of
chemical reactions,
a fundamental aspect
in fields ranging
from materials
science to
biochemistry. This
in-depth
understanding of
chemical processes
may allow for
precise control over
reaction dynamics,
thereby paving the
way for advancements
in technology and
medicine, for
example, by guiding
the development of
efficient catalysis,
innovative
materials, and
targeted drugs. In
this talk, I will
describe our work on
imaging
time-resolved
molecular dynamics
using two distinct
and complementary
techniques.
In the first part of
my talk, I will
discuss the use of
coincident Coulomb
explosion imaging
for the direct
visualization of
roaming reactions.
These reactions
represent
unconventional
pathways that allow
fragments to remain
weakly bonded,
leading to the
formation of
unexpected final
products. Typically,
the neutral
character of the
roaming fragment and
its indeterminate
trajectory make
direct experimental
identification
challenging.
However, I will
demonstrate that by
leveraging the power
of coincidence
imaging, we can
reconstruct the
momentum vector of
the neutral roamer
and thus identify an
unambiguous
signature for
roaming.
In the second part
of my talk, I will
discuss the imaging
of UV-induced
ring-opening and
dissociation
dynamics using
ultrafast electron
diffraction. I will
demonstrate that by
harnessing the
superior temporal
and structural
resolution of this
technique, we can
explore the
competition among
different molecular
pathways as well as
their
wavelength-dependent
behavior.
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June
17, 2024
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Dr.
Federico
Roccati
Columbia
University
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Quantum
optics in
(non-)Hermitian
topological photonic
reservoirs
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(Host:
Dominik
Schneble)
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Topology and
quantum optics are
two fields whose
interplay can give
rise to new physics
[1]. By properly
designing a photonic
lattice (i.e., the
structured
reservoir), it is
possible to engineer
photon-mediated spin
Hamiltonians between
quantum emitters
coupled to it. In
particular, it is
possible to endow
photonic structures
with Hermitian or
non-Hermitian
topological
properties, the
latter being typical
of dissipative
lattices [2]. In my
talk, I will cover
the recent
advancements in the
field, the current
experimental
implementations of
such setups, and our
recent results.
Specifically, I will
describe how,
engineering
dissipation (i.e.,
non-Hermiticity) in
a photonic lattice,
exotic interactions
can be mediated
between quantum
emitters,
unachievable in the
Hermitian case [3].
Finally, I will
illustrate the
topological
correspondence that
exists between the
topology of a
photonic lattice and
the topology of the
photon-mediated
interactions [4].
[1] M. Bello,
G. Platero, J. I.
Cirac, A.
González-Tudela.
Sci. Adv. 5,
eaaw0297 (2019).
[2] T. Ozawa et al.
Rev. Mod. Phys. 91,
015006 (2019).
[3] F. Roccati, S.
Lorenzo, G. Calajò,
G. M. Palma, A.
Carollo, F.
Ciccarello. Optica
9, 565-571 (2022).
[4] F. Roccati, M.
Bello, Z. Gong, M.
Ueda, F. Ciccarello,
A. Chenu, A.
Carollo. Nat Commun
15, 2400 (2024)
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