Spring/Summer 2019

January 28, 2019

Prof.
Peter D
Drummond
Swinburne
University of
Technology,
Melbourne,
Australia

Fundamental
tests of
physics and
simulations of
exponentially
complex
manybody
systems

(Host:
Jin Wang)


The physical universe is
not an
assembly of
mechanical
parts, as
envisaged
classically.
Instead,
quantum
mechanics
tells us that
the universe
is a manybody
state,
described by
an
exponentially
large Hilbert
space of
enormous size.
The standard
model
indicates what
the components
are: but what
emerges when
they evolve,
dynamically,
in time? In
this
colloquium, I
will give
results of
firstprinciples
quantum
simulations of
manybody
systems and
relate these
to fundamental
tests.
These will
include
accurate,
experimentally
tested quantum
dynamical
simulations of
the world's
most coherent
BoseEinstein
atom
interferometer.
These
simulations
are fully
quantum
mechanical.
They include
both thermal
and quantum
noise, as well
as linear and
nonlinear
collisional
losses, in
one, two and
three space
dimensions.
Experiments
that verify
the theory
were carried
out at
Swinburne
University.
Evidence is
obtained for
genuine
entanglement
and steering
of up to
40,000 atoms.
Methods to
simulate novel
technologies
will include:
optomechanical
entanglement,
quantum
memories for
'ondemand'
Schrodinger
Cats, and
mesoscopic
bright
solitons in
ultracold
gases.
Entanglement
predictions
were confirmed
in
electrooptic
experiments at
JILA. The
soliton
experiments
are underway
at Rice
University
using 7
Li. I will
also treat a
proposal to
simulate the
early universe
using an
ultracold
atomic
laboratory
model of the
quantum
fluctuations
in the 'Big
Bang'.
Who
needs a ship
in a bottle,
when you can
have a
universe on a
table top?
True
vacuum bubbles
forming in an
early universe
simulation.




February
25, 2019 [Wang
Center,
8:00am5:00pm]


SBUBNL Quantum Immersion
Workshop



The
goal of this
Quantum
Immersion
Workshop is to
build a
Quantum
Information
Science (QIS)
community of
researchers
between Stony
Brook
University,
Brookhaven
National
Laboratory,
and other
partners. This
workshop will
showcase state
of the art
research in
QIS and
provide a
forum to
discuss
opportunities
to engage in
QIS research.
Featuring four
sessions on:
Quantum
Networking and
Cryptography,
Quantum
Algorithms and
Programming
Environment,
Analog Quantum
Simulation,
Quantum
Devices and
Quantum
Materials.
Provost
Lecture:
"Building a
Quantum
Computer" by
Dr. Barry
Sanders,
Director of
the Institute
for Quantum
Science and
Technology at
the University
of Calgary.
Provost
Lecture:
"Quantum
Machine
Learning" by
Dr. Seth
Lloyd,
Professor of
engineering,
MIT




April 8, 2019

Xinjue
Zhong
Columbia
University

Probing
the Electronic
Properties of
Superatomic
Van der Waals
Semiconductors

(Host:
Tom Allison)


Twodimensional van der
Waals
materials
built from
clusters
featuring
atomic
precision
instead of
simple atoms
have attracted
great
attention due
to their
unique
collective
physical
properties and
tunable
structures and
functions. In
this talk, I
will describe
two van der
Waals
materials
derived from
the Chevrel
phases. The
strong
inplane
covalent
bonding and
weak
interlayer
interactions
allow
exfoliating
them down to
few layers.
The electronic
properties are
characterized
by using
scanning
tunneling
microscopy/spectroscopy,
photoluminescence,
polarization
dependent
Raman
spectroscopy
and first
principles
calculations.
In Re6Se8Cl2,
I determine
the electronic
bandgap,
optical
bandgap and
thus the
exciton
binding
energy. The
latter is as
large as 100
meV, which is
consistent
with the
partially 2D
nature of the
exciton. In
Mo6S3Br6, I
determine its
robust 2D
semiconducting
character and
strong
inplane
electronic
anisotropy.
The complex,
hierarchical
structures
with 2D
characters in
these two
materials
suggest an
exciting new
strategy to
design 2D
materials with
multifunctionality
and desired
electronic
properties.




April 15, 2019

Albert
Liu
University of
Michigan

Novel Electronic and
Vibrational
Properties of
Colloidal
Nanocrystals

(Host:
Tom Allison)


Colloidal nanocrystals
(CNCs) are
nanometer
sized crystals
grown in
solution. Due
to their
sizetunable
optical
properties,
CNCs have
emerged as a
novel material
platform for
numerous
applications
such as
displays,
photovoltaics,
and biological
tagging.
However, the
colloidal
growth process
results in an
unavoidable
distribution
of CNC size
that
inhomogeneously
broadens
optical
absorption/luminescence
lineshapes.
2D
spectroscopy
is a technique
capable of
circumventing
inhomogeneous
broadening by
correlating
absorption and
emission
dynamics. In
this talk I
will present
our results
from applying
2D
spectroscopy
to CNCs at
cryogenic
temperatures.
I will first
discuss our
experiments on
conventional
CdSe CNCs, in
which we have
simultaneously
observed both
bulklike
acoustic
phonons and
acoustic
vibrations
discretized by
the
nanocrystal
geometry for
the first
time. We also
find evidence
of highly
anharmonic
coupling to
longitudinal
optical
phonons. Next,
I discuss our
experiments on
perovskite
CNCs, which
are a new
class of
materials
first
synthesized in
2015. We
demonstrate
that by
coupling to
discrete
vibrational
modes, quantum
superpositions
of states
(coherences)
are insulated
from the
dominant
dephasing by
acoustic
vibrations and
are
â€œprotectedâ€.
Finally, I
discuss our
observations
of coherences
between
socalled
brighttriplet
exciton
states, which
are robust at
high
temperatures
and
polarizationselective.
These
intertriplet
coherences
offer a
potential
nanocrystal
analogue of
"valleytronics"
in 2D
materials




April 22, 2019

Prof.
Phillip L.
Gould
University of
Connecticut

Binding
Ultracold
Atoms into
Molecules
Using
FrequencyChirped
Light

(Host:
Hal Metcalf)


Ultracold molecules are
currently a
topic of great
interest in
AMO physics,
with potential
applications
ranging from
ultracold
chemistry to
quantum
computing. One
method for
forming such
molecules is
photoassociation,
where two
colliding
ultracold
atoms absorb a
photon and are
thereby bound
into an
excited
molecule. We
examine an
extension of
this process
in Rb dimers,
using
frequencychirped
light on the
nanosecond
time scale.
Within a
single chirped
pulse, the
photoassociation
process is
followed by
stimulated
emission which
transfers the
excited
molecule to a
bound level of
the electronic
ground state.
We show that
this twostep
process can be
enhanced by a
judicious
shape of the
chirp. Quantum
simulations of
the molecular
formation are
not only in
good agreement
with the
experimental
results, but
also give
insight into
the
enhancement
mechanism. Our
method for
producing the
nanosecond
frequencychirped
pulses will
also be
briefly
described.




April 23, 2019 (Tues, 2:00PM)

Prof.
Phillip L.
Gould
University of
Connecticut

Pushing Molecules with
Light: The
Bichromatic
Force

(Host:
Hal Metcalf)


Manipulating
and cooling
molecules are
topics of
significant
current
interest, with
potential
applications
ranging from
ultracold
chemistry to
precision
measurements
to quantum
computing.
Tremendous
progress has
recently been
realized in
slowing,
cooling, and
trapping of
molecules
using
radiation
pressure
forces.
However, these
forces are
limited in
magnitude by
the photon
scattering
rate. Larger
forces would
be beneficial,
especially for
more efficient
loading of
traps from
molecular
beams. A
potential
agent for
large
deceleration
is the
bichromatic
force, whereby
a
twofrequency
standing wave
allows
stimulated
emission to
significantly
enhance the
momentum
transfer. I
will describe
experiments
using the
bichromatic
force to
transversely
deflect a beam
of CaF. A
force
approximately
four times
that of
radiation
pressure has
been observed.
The large
magnitude of
this force,
coupled with
the reduced
rate of
spontaneous
emission,
indicates its
potential
utility in the
slowing and
manipulation
of molecular
beams.




April 29, 2019

Alice
Kunin
University of
California at
Berkeley

Ultrafast
dynamics of
electron
accommodation
in nucleobases

(Host:
Tom Allison)


Low energy electrons have
been shown to
attach to DNA
and induce
single and
double strand
breaks.
Theoretical
work has
implicated the
formation of
transient
negative ions
(TNIs) of
nucleobases as
the initial
step in the
damage
mechanism, but
these
shortlived
electronic
resonances are
challenging to
probe
experimentally.
Iodidenucleobase
clusters
studied by
timeresolved
photoelectron
spectroscopy
(TRPES) are an
opportune
model system
to examine
ultrafast
electron
attachment to
nucleobases as
well as the
subsequent
relaxation and
photodissociation
processes. By
initiating
charge
transfer from
iodide to the
nucleobase
with the TRPES
pump pulse and
following the
dynamics of
the nascent
TNIs, the
formation and
timeevolution
of both
dipolebound
and
valencebound
TNIs of
several
nucleobase
species have
been measured.
This talk will
explore in
detail our
recent work
investigating
the effects of
microhydration
on
iodidenucleobase
clusters to
provide
insight into
the role of
water and
solvation on
the dynamics
of electron
accommodation
and
photodissociation.




May 1,
2019 [YITP
Seminar,
2:30pm, YITP
Common Room]

Prof.
Andrea
Trombettoni
CNR &
SISSA,Trieste,
Italy
Dr. Nicolo
Defenu
University of
Heidelberg,
Germany

Equilibrium and Dynamical
Properties of
Quantum
LongRange
Spin Systems

(Host:
TzuChieh Wei
)


Several
recent
experiments in
atomic,
molecular and
optical
systems
motivated a
huge interest
in the study
of quantum
longrange
spin systems.
In the first
part of the
talk [by
Andrea
Trombettoni]
we discuss a
general
description of
their critical
behavior and
phases,
devising a
treatment
valid in d
dimensions,
with an
exponent
d+\sigma for
the powerlaw
decay of the
couplings in
the presence
of an O(N)
symmetry.
Results for
the
correlation
length
exponent, the
dynamical
critical
exponent z and
a comparison
with numerical
findings for
them
areÂ
presented. In
the second
part of the
talk
[30minutes, by
Nicolo'
Defenu], the
goal is to
present a
discussion of
dynamical
properties of
quantum
longrange
systems,
focusing on
slow quenches.
In systems
with
shortrange
interactions
the heat
exhibits
universal
powerlaw
scaling as a
function of
the quench
rate, known as
KibbleZurek
scaling. Slow
quenches of
the magnetic
field in
quantum
longrange
quantum
systems are
then analyzed,
showing that
it is possible
to
analytically
determine the
quantum
contribution
to the
residual heat
as a function
of the quench
rate by means
of a
HolsteinPrimakoff
expansion
about the
meanfield
value.




May 6, 2019

Prof.Joseph
Subotnik
University of
Pennsylvania

Electrodynamics for the
Chemist: How
should a
photochemist
think about
the
electromagnetic
radiation
fields?

(Host:
Tom Weinacht)


Within the physics and
chemistry
communities,
there is
currently an
enormous
interest in
the phenomena
of strong
lightmatter
coupling.
Whether in
cavities or in
plasmonic
materials,
there is today
clear evidence
that the
quantum nature
of light and
matter can
become
entangled in
very
interesting
ways, and
moreover there
is hope that
this
entanglement
can be
exploited and
lead to new
devices
In order to
predict
lightmatter
behavior, one
outstanding
question is:
how can we
best model
lightmatter
systems in a
predictive
manner so that
we can model
large,
realistic
systems and
gain intuition
for quantum
electrodynamics?
In this talk,
I will
highlight our
recent
attemptsto
semiclassically
merge the
Schrodinger
equation with
Maxwell's
equations so
as to recover
the essential
effects of
strong
lightmatter
coupling (that
are not
captured
classically).Â
This work in
semiclassical
electrodynamics
draws on much
older (and
more
developed)
work in
semiclassical
nonadiabatic
molecular
dynamics,
highlighting
the fact that
many
outstanding
questions
remains at the
intersection
of chemical
and atomic
physics.




May 7,
2019 [Nuclear Physics Group Seminar,1pm,
C120]

Prof.
Yannick
Meurice
University of
Iowa

Quantum Field Theory with
Cold Atoms?

(Host:
Dmitri
Kharzeev)


We
review
tensorial
formulations
of lattice
gauge/spin
theories and
algorithmic
aspects of
their coarse
graining. We
discuss
truncations
and show that
they preserve
the symmetries
of the
original
lattice models
(arXiv:1903.01918).
We show that
tensor
reformulations
fit the needs
of quantum
computation.
We discuss
concrete
proposals of
quantum
simulation
experiments
with cold
atoms for the
Abelian Higgs
model
and
other simple
models in 1+1
dimensions.
We
discuss
methods to
measure the
second order
Renyi
entanglement
entropy with
cold atoms.
We
report recent
calculations
for real time
scattering for
the quantum
Ising model
(arXiv:1901.05944)
and
discuss
the errors
associated
with the
Trotter step
size and gate
errors for
existing or
near term
quantum
computers
(such as IBM
or trapped
ions devices).




May 20, 2019

Prof.Jiehang
Zhang
New York
University

Quantum ManyBody Spin
Systems
Engineered
from Trapped
Atomic Ions

(Host:
Tom Weinacht)


Quantum mechanics
prescribes
exponential
scaling of the
Hilbert space
dimension in
manybody
systems, which
presents both
challenges and
new
opportunities
for
understanding
strongly
correlated
matter,
especially
since novel
custombuilt
systems are
now available.
I will
describe such
efforts on
engineering
quantum
systems atom
by atom,
precisely
controlling
them with
laserdriven
interactions,
and increasing
the system
size up to a
regime where
the
capabilities
of classical
computers are
challenged.
I will focus
on the
platform of
trapped atomic
ions, where a
combination of
excellent
coherence time
and
highfidelity
measurements
has enabled
many
applications,
ranging from
simulating
condensed
matter
physics, to
quantum
computation.
We represent
spin qubits
with
electronic
levels of ions
in a Coulomb
crystal, and
entangle them
through
tailored laser
pulses. I will
present recent
experiments
using these
systems to
study
dynamical
phase with
individual
resolution for
more than 50
spins [1], as
well as
nonequilibrium
driven matter
such as
discrete time
crystals [2].
I then
conclude with
some future
prospects.
[1] J. Zhang,
et al., Observation
of a manybody
dynamical
phase
transition
with a
53qubit
quantum
simulator,
Nature, vol.
551, p. 601,
Nov. 2017
Â [2] J.
Zhang, et al.
Observation
of a discrete
time crystal,
Nature, vol.
543, pp.
217–220, Mar.
2017




August 19, 2019

Prof.
Agnes Vibok
University of
Debrecen,
Hungary

Classical and Quantum
FieldDressed
Spectra of the
Sodium
Molecule

(Host:
Tom Weinacht)


In classical laser fields
with
frequencies
resonant with
the electronic
excitation in
molecules, it
is by now
known that
conical
intersections
are induced by
the field and
are called
lightinduced
conical
intersections
LICIs). As
optical
cavities have
become
accessible
their
quantized
modes could
also lead to
the appearance
of LICIs. In
the present
work
theoretical
frameworks are
formulated for
the
investigation
of LICIs of
diatomics in
such a
classical and
quantum light
circumstances.
As an example
by employing a
weak measuring
pulse the
dressed state
absorption
spectra of the
Na2 molecule
are
investigated
both in a
cavity and in
an optical
lattice.



