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Fall 2016
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September 19, 2016
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Prof.
Jiannis Pachos
University of
Leeds, UK
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Majorana
fermions in a
photonic
quantum
simulator
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(Host:
Dominik
Schneble)
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The
realization of
Majorana
fermions is in
the centre of
intense
theoretical
and
experimental
investigations.
Unfortunately,
their exchange
that can
reveal their
exotic
statistics
needs
manipulations
that are still
beyond our
experimental
capabilities.
In this
pedagogical
talk I will
present an
alternative
approach to
this problem.
Through the
Jordan-Wigner
transformation,
the Kitaev’s
chain
supporting two
Majorana
fermions can
be mapped to
the Ising
spin-1/2
chain. We
experimentally
simulated the
spin system
and its
evolution with
a photonic
quantum
simulator. By
studying the
induced
geometric
phases we were
able to
simulate the
exchange of
two Majoranas
positioned at
the ends of a
three-site
chain. the
immunity of
the
topologically
encoded
quantum
information is
also
demonstrated
against local
errors.
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September 26, 2016
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Andreas
Schindewolf
University of
Innsbruck,
Austria
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low-entropy
gas of RbCs
molecules in
an optical
lattice
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(Host:
Dominik
Schneble)
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Quantum
many-body
systems with
long-range
dipolar
interaction
are currently
of immense
interest in
the theory and
experiment
community.
Until
recently,
experimental
realization
with dipolar
molecules was
unfeasible due
to high sample
entropy. We
present a
novel method
to prepare
low-entropy
samples of
molecules as
an ideal
starting point
for such
experiments
[1].
Starting from
two spatially
separated
BECs, we form
Rb-Cs
precursor
pairs by
overlapping a
Cs Mott
insulator with
superfluid Rb
in an optical
lattice. For
this purpose,
the Rb-Cs
interaction is
nulled at a
Feshbach
resonance's
zero crossing.
After the Rb
atoms are
localized by
further
enhancing the
lattice depth,
the paired
atoms are
associated to
Feshbach
molecules by
means of the
aforementioned
Feshbach
resonance.
With this
method we
produce a
low-entropy
molecular
sample with a
filling
fraction
exceeding 30%.
Combining the
method with a
STIRAP
technique to
produce
dipolar
ground-state
molecules,
which we
already
realized with
90% efficiency
[2], we will
be able to
address
experiments in
the context of
dipolar
many-body
physics.
[1]
arXiv:1607.06536
[2] Phys. Rev.
Lett. 113,
263201 (2014)
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October 6, 2016
(Thurs,
4pm in
SCGP-102)
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Prof.
Maxim Olshanii
University of
Massachusetts
Boston
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Quantum
Galilean
Cannon as a
Schrödinger
Cat
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SCGP Workshop: Entanglement in Quantum Systems
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October 14, 2016 (Fri, 3pm)
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Dr.
Oleg Pronin
MPQ Garching,
Germany
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High-power
femtosecond
thin-disk
oscillators
for
mid-infrared
and extreme
ultraviolet
generation
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(Host:
Tom Allison)
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Recent
advances in
the
development of
femtosecond
thin-disk
oscillators
are reported.
A novel
mode-locking
technique
relying on
distributed
Kerr-lenses is
presented. The
generation of
W-level
mid-infrared
frequency comb
is described.
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October 19, 2016 (Wed)
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Krupa
Ramasesha
Sandia
National
Laboratory
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Condensed
phase
vibrational
and electron
dynamics
probed using
ultrafast
nonlinear
spectroscopy
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(Host:
Tom Allison)
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This
talk will
present
ultrafast
spectroscopic
investigations
of condensed
phase dynamics
on attosecond
to picosecond
timescales.
The first part
will discuss
coherent
two-dimensional
infrared (2D
IR)
spectroscopy
of hydrogen
bonding and
vibrational
dynamics in
liquid water,
where
experimental
evidence of
large angle
reorientation
responsible
for inertial
hydrogen bond
switching was
observed, and
evidence of
highly coupled
intra- and
inter-molecular
vibrations of
liquid water
was seen,
resulting in
rapid and
efficient
energy
dissipation.
The second
part will
focus on
attosecond
extreme
ultraviolet
spectroscopy
of electron
dynamics in
silicon, where
evidence for
strong field
tunneling of
electrons
across the
band gap,
carrier-carrier
interaction,
band gap
renormalization
and
field-induced
shifts were
observed.
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October 24, 2016
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Sergei
Nazarenko and
Chris Presuto
Photonics
Industries
International,
Inc.
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Technology
and
Applications
of Diode
Pumped Solid
State
Picosecond
Lasers
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(Host:
Hal Metcalf)
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Two
Stony Brook
Physics alumni
discuss their
work at
Photonics
Industries
International,
a local
company that
is innovating
advances in
the growing
field of
picosecond
pulsed DPSS
lasers. This
will be an
overview of
the current
cutting edge
of industrial
laser
technology,
including
picosecond
pulse
generation,
amplification,
and nonlinear
frequency
conversion. We
will also
discuss
current laser
applications
in industry
and research,
and discuss
some of the
challenges
faced when
bringing an
idea from a
test-bench to
a mass
producible
manufactured
product.
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November 1, 2016
(Tues,
4pm in
Harriman-137)
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Prof.
Thomas Killian
Rice
University
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Studying
Collisions and
Transport in
Strongly
Coupled
Systems with
Ultracold
Plasmas
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Physics & Astronomy Colloquium
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Ultracold
neutral
plasmas,
formed by
photoionizing
laser-cooled
atoms near the
ionization
threshold,
explore matter
at the
intersection
of atomic,
soft condensed
matter, and
plasma
physics.
Because of the
low electron
and ion
temperatures
(Te=1-1000K
and Ti=1K),
the Coulomb
interaction
energy per
particle can
exceed the
thermal
energy, which
makes the
system
strongly
coupled.
Strong
coupling is of
interest in
many areas of
physics. It
leads to
spatial
correlations
and surprising
equilibration
dynamics, and
it makes
theoretical
description
much more
difficult.
Ultracold
plasmas
provide a
valuable
window into
these
phenomena
because of the
excellent
control of
initial
conditions and
diagnostics
that are
available. I
will describe
recent results
that give the
first
measurement of
equilibration
rates [1] and
diffusion
coefficients
in the
strongly
coupled regime
[2], which are
relevant for
plasmas
produced
through
short-pulse
laser
irradiation of
solid targets,
such as in
inertial
confinement
fusion. The
dynamics also
shows
non-Markovian
or memory
effects that
are
reminiscent of
the behavior
of metal
liquids.
[1] “Velocity
Relaxation in
a Strongly
Coupled
Plasma,” G.
Bannasch, J.
Castro, P.
McQuillen, T.
Pohl and T. C.
Killian, Phys.
Rev. Lett.
109, 185008
(2012).
[2]
“Experimental
Measurement of
Self-Diffusion
in a Strongly
Coupled
Plasma,” T. S.
Strickler, T.
K. Langin, P.
McQuillen, J.
Daligault, and
T. C. Killian,
Phys. Rev. X
6, 021021
(2016).
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November 2, 2016 (Wed, 3pm)
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Prof.
Thomas Killian
Rice
University
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From
Ultralong-range
Molecules to
Rydberg
Polarons in a
Bose Gas
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(Host:
Hal
Metcalf/Dominik
Schneble)
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Rydberg
atoms excited
in a dense gas
interact very
strongly with
background,
ground-state
atoms that lie
within the
Rydberg
orbital. This
problem has a
long history,
and it
inspired Fermi
to develop the
Fermi
pseudo-potential
to describe
the low-energy
scattering of
a Rydberg
electron and
ground-state
atoms. With
the
availability
of ultracold
atomic gases,
this topic has
received
renewed
interest.
I will
describe the
excitation of
Rydberg atoms
in a
Bose-Einstein
condensate of
strontium
atoms. In a
few-body
regime, we
observe a
dense, highly
structured
spectrum
reflecting
excitation of
ultralong-range
molecules
consisting of
one or more
ground-state
atoms bound to
the Rydberg
core in
potential
wells formed
by the
Rydberg-electron
wave function.
This
represents a
new molecular
bonding
mechanism and
novel ultacold
chemistry. In
a many-body
regime, with
hundreds of
ground-state
atoms within
the Rydberg
orbital, the
Rydberg atoms
can be viewed
as an impurity
in a quantum
gas,
connecting to
important
concepts in
condensed
matter
physics. The
spectrum for
impurity
excitation
displays
signatures of
polaronic
states, in
which the
Rydberg atom
significantly
perturbs the
density of the
background
Bose gas.
In the low
energy range
probed in
these
experiments,
the scattering
of electrons
from
ground-state
strontium
atoms lacks a
p-wave
resonance.
Such a
resonance
plagues alkali
atoms that
have
previously
been used to
study Rydberg
excitation in
dense,
ultracold
gases. This
leads to
enhanced
Rydberg-atom/molecule
lifetime for
strontium, and
is critical
for modelling
the spectrum
in the
many-body
regime and
probing the
physics of
polarons.
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November 4, 2016
(1:30pm
in B-141)
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Prof.
Fabio
Franchini
Ruder Boskovic
Inst.- Zagreb,
Croatia
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Universal
Dynamics of a
localized
excitation
after an
interaction
quench
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Condensed-matter physics seminar
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November 7, 2016
(2:30pm
in SCGP-313)
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Prof.
Andrea
Trombettoni
SISSA-Trieste,
Italy
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Tunneling-based
quantum
devices with
ultracold
strongly
interacting
atoms
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SCGP Program: Entanglement and Dynamical Systems
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November 21, 2016
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Dr.
Leland
Aldridge
University of
Connecticut
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The
Bichromatic
Force in
Multi-Level
Systems
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(Host:
Hal Metcalf)
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The
optical
bichromatic
force (BCF)
has been
previously
demonstrated,
in two-level
atomic
systems, to
produce forces
significantly
in excess of
the maximum
achievable
radiative or
photon
scattering
force. Its
application to
multilevel
systems has
been less well
understood. I
present
examinations
of BCF in
various simple
multilevel
systems, which
inform
prescriptions
for the
application of
the BCF to
general
multilevel
systems. I
apply these
prescriptions
to simulations
of the
molecular
systems CaF
and SrOH and
show that BCF
is feasible in
these
molecules, and
discuss
planned
experiments to
measure BCF
deflection of
a molecular
beam of CaF.
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