Seminars
will be held held
at room S-141 in the Physics and
Astronomy Department building on
Mondays at 4:00 PM, unless noted
otherwise.

Spring/Summer 2013

January 25, 2013, 3:00 PM

Michael
Bellos, University
of Connecticut

Optical
production
of
Ultracold Rb2
molecules in
states with a
magnetic or
electric
dipole moment

(Host:
DominikSchneble)

I
would like to
review
different ways
for forming
molecules out
of
ultracold
atoms, with an
emphasis on
photoassociation.
Photoassociation
is the process
of converting
two atoms and
a photon into
a bound
molecule. I
will touch on
photoassociation
at short range
and
photoassociation
into
resonantly-coupled
levels as two
ways of
forming
deeply-bound
molecules.
Finally, I
will describe
recent work on
"butterfly"
states---a
class of
excited states
with a large
electric
dipole
moment---that
result from a
novel form of
chemical
binding.

February 4, 2013

Prof.
Peter Engels, WashingtonStateUniversity

New
trends in BEC
hydrodynamics:
novel types of
solitons
and dispersion
engineering

(Host:
DominikSchneble)

The
peculiar
dynamics of superfluids
are a
fascinating researchtopic.
Sincethe
first
generation of
a dilute gas
Bose-Einstein
condensate
(BEC) in 1995,
quantum
degenerate
atomic gases
have taken the
investigation
of quantum
hydrodynamics
to a new
level. The
atomic physics
toolbox has
grown
tremendously
and now
provides
unique and
powerful ways
to explore
nonlinear
quantum
systems.
As an example,
pioneering
results have
recently
revealed that
the counterflow
between two superfluids
can be used as
a well
controlled
tool to access
the rich
dynamics of
vector
systems. New
structures,
such as
beating
dark-dark solitons
which only
exist in multicomponent
systems and
have never
been observed
before, can
now be
realized in
the lab for
the first
time.
Furthermore,
the field of
nonlinear
quantum
hydrodynamics
is entering
new regimes by
exploiting
Raman dressing
as a tool to
directly
modify the
dispersion
relation. This
leads to the
generation of
spin-orbit
coupled BECs,
artificial
gauge fields,
etc. that are
currently
receiving
tremendous
interest due
to their
parallels to
complex
condensed-matter
systems.
In this talk I
will present
the recent and
ongoing
experiments at
WSU that focus
on novel types
of solitons
as well as
Raman-dressed
BECs.

February 11, 2013

Prof.
Subhadeep
Gupta, University
of Washington

Quantum
Mixtures of
Alkali and
Alkaline-Earth-Like
Atoms

(Host:
DominikSchneble)

We
have produced
quantum
degenerate
mixtures of
ytterbium (Yb)
and lithium
(Li) atoms.
Such a
mass-mismatched
mixture can be
useful for
various
studies in
few- and
many-body
physics.
Furthermore,
this
combination
(of an
alkaline-earth-like
and an alkali
atom) also
forms the
starting point
for the
production of
ultracold
paramagnetic
polar
molecules,
with proposed
applications
in quantum
simulation,
quantum
information
science, and
precision
tests of
fundamental
physics. In
addition to
our production
procedures, I
will also
report on our
study of the
collisional
stability of
the Yb-Li
mixture in the
vicinity of a
Li Feshbach
resonance. In
our
experiment, Yb
can be
prepared as
either a bath
for or a probe
of the
strongly
interacting Li
Fermi
gas. I
will also
discuss the
prospects for
tunable
inter-species
interactions
and the YbLi
molecule.

February 25, 2013

Prof.
DoerteBlume,
WashingtonStateUniversity

S-Wave
Interacting
Fermions Under
Anisotropic
Harmonic
Confinement:
Dimensional
Crossover of Energetics
and Virial
Coefficients

(Host: Tom Bergeman)

Few-body
physics has
played a
prominent role
in atomic,
molecular,
chemical and
nuclear
physics since
the early days
of quantum
mechanics. It
is now
possible---thanks
to tremendous
progress in
cooling,
trapping, and
manipulating ultracold
samples---to
experimentally
study few-body
phenomena in
trapped atomic
and molecular
systems with
unprecedented
control. This
talk
summarizes
recent studies
of few-body
phenomena in
trapped fermionic
gases. We
present
essentially
exact
solutions of
the
Schrodinger
equation for
three
equal-mass
fermions in
two different
spin states
with
zero-range
s-wave
interactions
and discuss
the transition
from
quasi-one-dimensional
to strictly
one-dimensional
and
quasi-two-dimensional
to strictly
two-dimensional
geometries. We
determine and
interpret the
eigenenergies
of the system
as a function
of the trap
geometry and
the strength
of the s-wave
interactions.
The eigenenergies
are used to
investigate
the dependence
of the second-
and
third-order virial
coefficients,
which play an
important role
in the virial
expansion of
the
thermodynamic
potential, on
the geometry
of the trap.
We show that
the second-
and
third-order virial
coefficients
for aniostropic
confinement
geometries
are, for
experimentally
relevant
temperatures,
very well
approximated
by those for
the
spherically
symmetric
confinement
for all s-wave
scattering
lengths.

March 4, 2013

Dr.
Denys Bondar,
Princeton
University

To
commute or not
to commute,
that is
everyting to
know about
classical and
quantum
mechanics

(Host: Tom Weinacht)

We
introduce
Operational
Dynamic
Modeling (ODM)
as
asystematic
theoretical
framework for
deducing
equations
ofmotion from
the evolution
of observed
average
values. Then,
it is
demonstrated
that ODM is
capable of
deriving wide
ranging
dynamics
including
classical and
quantum
mechanics.

April 1, 2013

Anita
Madan and
Michael
Hatzistergos,
IBM

Science
in the
Semiconductor
Industry -
Perspectives
and Challenges

(Host: Hal Metcalf)

With
the continuing
demand for
faster
chips,
chips get
smaller and
smaller.
There are
accompanying
challenges in
their
characterization.
State of the
art techniques
are needed.
Our talk will
focus on two
of the cutting
edge
characterization
techniques
used in our
industry -
X-ray
techniques for
characterizing
strain and
Atom Probe
Tomography for
determining
the positions
of the atoms.
We
will also
describe how
skills
acquired as
science
undergraduates
as well as in
graduate
school have
been helpful
in our current
jobs.

April 8, 2013

Prof.
Maxim
Olshanii,
University of
Massachusetts
at Boston

Geometry
of Quantum
Observables,
Integrability-Thermalizability
Transition,
and Extended
Thermodynamics
of Integrable
and/or
Mesoscopic
Systems

(Host: Tom Bergeman)

The
concept of
ergodicity—--the
convergence of
the temporal
averages of
observables to
their ensemble
averages---is
the
cornerstone of
thermodynamics.
The transition
from a
predictable,
integrable
behavior to
ergodicity is
one of the
most difficult
physical
phenomena to
treat; the
celebrated KAM
theorem is the
prime example.
This talk is
founded on the
observation
that for many
classical and
quantum
observables,
the sum of the
ensemble
variance of
the temporal
average and
the ensemble
average of
temporal
variance
remains
approximately
constant
across the
integrability-ergodicity
transition.
We
show that this
property
induces a
particular
geometry of quantum
observables—--Frobenius-Hilbert-Schmidt
one—--that
naturally
encodes all
the phenomena
associated
with the
emergence of
ergodicity:
the Eigenstate
Thermalization
effect, the
decrease in
the inverse
participation
ratio, and the
disappearance
of the
integrals of
motion. As an
application,
we use this
geometry to
solve a known
problem of
optimization
of the set of
conserved
quantities---coming
from
symmetries or
from
finite-size
effects,
regardless---to
be
incorporated
in an extended
thermodynamical
theory of
integrable,
near-integrable,
or mesoscopic
systems.

April 15, 2013

Dr.
Xijie Wang,
Brookhaven
National
Laboratory

Filling
the Ultrafast
Gaps: FEL, THz
and UED
R&D at BNL
Source
Development
Laboratory

(Host: Tom Weinacht)

Synchrotron
radiation
sciences have
witnessed an
explosive
growth in the
last few
decades thanks
to the advance
in the
electron
storage ring
and insertion
device
technologies,
leading a
drastic
increase in
the x-ray
brightness.
Advance in
laser
technology has
been similarly
spectacular:
pulse
compression
technique
giving rise to
femtosecond
terawatts
pulses and
high-harmonic
generation
technique for
shorter
wavelength
coverage have
opened up new
frontiers in
laser
spectroscopy
and dynamics
studies.But there are still
significant
gaps in our
scientific
toolbox,such as simultaneous having
atomic spatial
and temporal
resolution
(ultrafast
gap); high
power THz
source (THz
gap).Free
electron laser
(FEL) and
Ultrafast
Electron
diffraction
(UED) are two
most important
technologies
for filling
the ultrafast
gap, and
coherent
radiation from
high-brightness
electron beam
has
demonstrated
the potential
for high power
THz
generation.
Source
Development
Laboratory
(SDL) at
Brookhaven
National
Laboratory(BNL) has made critical
contributions
filling the
ultrafast and
THz gaps.
After a brief
introduction
on FEL
physics, I
will discuss
some exciting
FEL, THz and
UED
experimental
results this
talk.

April 22, 2013

Prof.
Long Cai
California
Institute of
Technology

Single
cell analysis
by
super-resolution
barcoding

(Host: Hal Metcalf)

Fluorescence
microscopy is
a powerful
quantitative
tool for
exploring
regulatory
networks in
singl
cells.
However, the
number of
molecular
species that
can be
measured
simultaneously
is limited by
the spectral
separability
of
fluorophores.
Here we
demonstrate a
simple but
general
strategy to
drastically
increase the
capacity for
multiplex
detection of
molecules in
single cells
by using
optical
super-resolution
microscopy
(SRM) and
combinatorial
labeling.
The basis for
this new
approach are
the following:
given the 10
nanometers
resolution of
a
super-resolution
microscope and
a typical cell
a size of
(10um)3,
individual
cells contains
effectively
109
super-resolution
pixels or bits
of
information.
Most
eukaryotic
cells have 104
genes and
cellular
abundances of
10-100 copies
per
transcript.
Thus, under a
super-resolution
microscope, an
individual
cell has 1000
times more
pixel volume
or information
capacities
than is needed
to encode all
transcripts
within that
cell. As
a proof of
principle, we
labeled mRNAs
with unique
combinations
of
fluorophores
using
Fluorescence
in situ
Hybridization
(FISH), and
resolved the
sequences and
combinations
of
fluorophores
with
SRM.
We measured
the mRNA
levels of 32
genes
simultaneously
in single
yeast
cells.
These
experiments
demonstrate
that
combinatorial
labeling and
super-resolution
imaging of
single cells
provides a
natural
approach to
bring systems
level analysis
into single
cells.

April 23, 2013 (P&A
COLLOQIUM)

Prof.
Jun Ye,
JILA / UC
Boulder

Ultracold
Molecules -
New Frontiers
in Quantum
& Chemical
Physics

(Host: Dominik Schneble)

Molecules
cooled to
ultralow
temperatures
provide
fundamental
new insights
to molecular
interaction
dynamics in
the quantum
regime. In
recent years,
researchers
from various
scientific
disciplines
such as
atomic,
optical, and
condensed
matter
physics,
physical
chemistry, and
quantum
science have
started
working
together to
explore many
emergent
research
topics related
to cold
molecules,
including cold
chemistry,
strongly
correlated
quantum
systems, novel
quantum
phases, and
precision
measurement.
Complete
control of
molecular
interactions
by producing a
molecular gas
at very low
entropy and
near absolute
zero has long
been hindered
by their
complex energy
level
structure. We
have recently
developed a
number of
technical
tools to laser
cool and
magneto-optically
trap polar
molecules, as
well as to
cool molecules
via
evaporation.
Another recent
experiment has
brought polar
molecules into
the quantum
regime, in
which
ultracold
molecular
collisions and
chemical
reactions must
be described
fully quantum
mechanically.
We control
chemical
reaction via
quantum
statistics of
the molecules,
along with
their
long-range and
anisotropic
dipolar
interactions.
Further,
molecules can
be confined in
reduced
spatial
dimensions and
their
interactions
are precisely
manipulated
via external
electric
fields. Those
efforts have
started to
yield
observations
on strongly
interacting
and collective
quantum
effects in an
ultracold gas
of molecules.

April 29, 2013

Dr.
Xi Xing,
Princeton
University

Optimal
Control over a
Homologous
Chemical
Series

(Host: Tom Weinacht)

Optimal
control
experiments
can readily
identify
effective
shaped fs
laser pulses,
or "photonic
reagents",
that achieve a
wide variety
of
objectives.
This talk will
focus on the
studies of
control
fragmentation
with a series
of homologous
molecules
(halomethanes
containing two
or three
halogen
atoms), where
the control
objectives are
to maximize
the ratios of
halogen over
methyl halogen
fragment ions
upon
dissociative
ionization.
I will show
that effective
controls can
be achieved
with reduced
dimensionality
in control
parameters;
the optimal
photonic
reagents
identified
from each
molecule show
systematic
trends in
objective
yield when
cross applied
to analogous
molecules; the
prescription
of photonic
reagents can
be
successfully
transferred
from one lab
to
another.
These results
provide a
basis to
expect
chemical
responses from
photonic
reagents in
analogy to the
action of
traditional
chemical
reagents.

April 30, 2013 (P&A
COLLOQIUM)

Prof.
Randall G
Hulet,
Rice
University

Quantum
Simulation
with Atoms in
Optical
Lattices

(Host: Dominik Schneble)

Some
of the most
complex and
vexing
problems in
electronic
materials are
modeled by
extremely
simple
Hamiltonians.
High-temperature
superconductors,
for example,
may arise from
magnetic
interactions
in a Mott
insulating
state,
described by
the simple
Hubbard model.
The Hubbard
model
stipulates
that particles
(electrons in
the case of
superconductors)
are
distributed in
a square
lattice where
they can hop
from site to
site with a
tunneling
energy t, and
where they may
interact with
occupied
nearest
neighbor sites
with
interaction
energy U. No
one knows
whether this
simple
“hydrogen-atom”
model actually
gives rise to
the d-wave
pairing
underlying the
cuprate
superconductors,
as the model,
while simple
to describe,
is not
solvable using
digital
computers. I
will discuss
two
experiments
that use
ultracold
atoms in an
optical
lattice as
stand-ins for
the electrons
in ionic
lattices: 1)
the Hubbard
model in 3D;
and 2) the
polarized
spin-½ Fermi
gas in 1D. In
the first
experiment, we
are searching
for the
anti-ferromagnetic
Mott
insulating
state that is
expected to
exist above
the
superconducting
transition
when there is
exactly
one-atom per
lattice site.
We have used
Bragg
scattering of
near-resonant
light to
characterize
the lattice,
and will use a
spin-sensitive
variant of
this tool to
detect
magnetic
correlations.
In the second
experiment, we
have used an
optical
lattice in
two-dimensions
to create a
bundle of 1D
tubes
containing an
imbalanced two
spin-state
mixture of 6Li
fermions. The
phase diagram
of this system
contains three
phases: a
fully-paired
superfluid, a
fully-polarized
ferromagnet,
and a
partially
polarized
state that is
predicted to
be the exotic
FFLO
superfluid
state, for
which the
pairs have
non-zero
center of mass
momentum.

May 6, 2013

Dr.
Melanie
Roberts,
Stony Brook
University

High-Resolution
Direct-Absorption
Spectroscopy
of
Supersonically-Cooled
Radicals in
the
Mid-Infrared
Region

(Host: Tom Allison)

The
energy of the
mid-infrared
region
generally
corresponds to
the amount of
energy
required to
excite
bond-stretching
vibrations in
molecules.
Using the
technique of
high-resolution
direct-absorption
spectroscopy
we obtain the
energy levels
of vibration,
rotation, and
occasionally
nuclear fine
and hyperfine
interactions
in molecules
in order to
learn about
bonding and
structure of
the molecule.
This talk will
focus on
absorption
spectroscopy
of
highly-reactive
radicals
important in
combustion
chemistry.
Absorption
spectra were
recorded using
a widely
tunable,
narrow
linewidth
(<1 MHz),
cw
mid-infrared
spectrometer
capable of
determining
and
reproducing
frequencies to
three parts in
108 with
absorption
noise levels
at or near the
shot noise
limit. To
generate the
highly
reactive and
short lived
radicals, a
discharge
breaks apart a
stable
precursor
molecule. The
discharge is
localized at
the orifice of
a slit
supersonic
expansion,
which cools
the radicals
to around 20 K
and allows for
sub-Doppler
spectral
resolution.
By way of
example, the
two
fundamental CH
stretches in
CH2D are
studied with
full
rotational
resolution for
the first
time. The
narrow
linewidths
(50-100 MHz)
of the
transitions
reveal
resolved fine
structure and
partially
resolved
hyperfine
structure. In
addition to
the
experimental
efforts on
CH2D, we
developed the
first model
capable of
simultaneously
describing the
CH and CD
stretches of
all the
hydrogenic
isotopomers of
methyl
radical.

May 7, 2013, 10:30am

Michael
Schecter,
University of
Minnesota

Dynamics
of mobile
impurities in
one-dimensional
quantum
liquids

(Host: Dominik Schneble)

The
study of
dissipationless
flow is an
active field
which
continues to
fascinate
researchers.
Impurity
motion through
a
one-dimensional
(1D)
superfluid is
one example
which has
brought
several
surprises.
Even for weak
coupling, the
single-impurity
dispersion
relation is
strongly
renormalized
when the
momentum
approaches
$\pm\pi\hbar
n$, where $n$
is the fluid
density. At
yet larger
momentum, one
finds that the
dispersion
relation is
actually
transformed
into a
\emph{periodic}
function, with
period
$2\pi\hbar n$.
We show that
this
remarkable
feature leads
to Bloch
oscillations
of a driven
impurity for a
large range of
temperatures
and external
drives.
-- We also
find that for
sufficiently
heavy
impurities the
dispersion
develops
non-analytic
cusps at
momenta
$j\pi\hbar n$
where $j$ is
an odd
integer. Such
cusps are
accompanied by
metastable
upper branches
which have
dramatic
consequences
for impurity
motion,
including the
divergence of
the
zero-temperature,
non-linear
mobility.
-- For a
dilute
concentration
of impurities,
one typically
regards the
latter as
non-interacting
and
independent.
However, in 1D
even weakly
interacting
quasi-particles
tend to be
unstable
against the
formation of
collective
excitations.
Thus, even for
the case of
non-interacting
impurities,
one should
consider the
possibility of
emergent
impurity
interactions
arising from
mutual
coupling to
one and the
same fluid. We
find that the
massless and
quantum nature
of low-energy
fluid
fluctuations
mediates a
universal
inter-impurity
potential
scaling as the
inverse cube
of the
separation.

June 10, 2013, 4:00 PM

Dr. Stephan Ritter
Max Planck
Institute for
Quantum Optics
(Germany)

An
Elementary
Quantum
Newtwork of
Single Atoms
in Optical
Cavities

(Host: Eden Figueroa)

Quantum
networks form
the basis of
distributed
quantum
computing
architectures
and quantum
communication.
Single atoms
in optical
cavities are
ideally suited
as universal
quantum
network nodes
capable of
sending,
storing and
retrieving
quantum
information.
We demonstrate
this by
presenting an
elementary
version of a
quantum
network based
on two
identical
nodes in
remote,
independent
laboratories.
The reversible
exchange of
quantum
information
and the
creation of
remote
entanglement
are achieved
by exchange of
a single
photon. The
dynamic
control of
coherent dark
states allows
for the
generation of
a single
photon in one
system, which
is
subsequently
stored at the
other node. A
heralded
alternative to
the direct
state transfer
is provided by
teleportation,
which we
implement
using a
time-resolved
photonic
Bell-state
measurement
based on
two-photon
quantum
inference.
Quantum
control over
all degrees of
freedom of the
single atoms
and our
cavity-based
approach to
quantum
networking
offer a clear
perspective
for
scalability.

June 12, 2013, 11:00 AM

Dr. Sotir
Chervenkov
Max Planck
Institute for
Quantum Optics
(Germany)

A
Roadmap for
Production of
Ultracold
Polyatomic
Polar
Molecules

(Host: Eden Figueroa)

Producing
ensembles of
polyatomic
molecules at
ultracold
temperatures
is a
challenge. In
pursuit of
this goal, we
propose a very
general scheme
combining
sequentially
three
promising
techniques.
First,
high-flux
continuous
supersonic
beams of
internally
cold polar
molecules are
produced from
a buffer-gas
cell [1, 2]
operated in
the
hydrodynamic
regime. Then
those beams
are guided in
an
electrostatic
guide [3] and
decelerated by
the
centrifugal
potential in a
rotating
frame. The
decelerated
continuous
beams are
delivered to
an
electrostatic
trap, where
the molecules
are further
cooled down
via a Sisyphus
process [4]
employing
laser,
microwave, and
radiofrequency
radiation.
Here we
demonstrate
experimental
results from
the three
techniques and
give evidence
for the
viability of
their joint
operation en
route to
achieving
sub-milliKelvin
ensembles of
polyatomic
polar
molecules.
[1] L. D. van
Buuren et al.,
Phys. Rev.
Lett. 102,
033001 (2009)
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