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The scientific process was developed as a means to understanding the world around us. It is a systematic approach to reaching the unknown, and consists of fixed and unknown variables. At the beginning of an inquiry the known variables are identified and utilized within the experiment. But working with what is known and predictable can only go so far. It is with the introduction of the unpredictable that gaps are bridged and a new lens to see is created. It is this methodology that is at the foundation of my art practice. Please see Download button in top right corner for the full statement
Simulation of Jahn-Teller-Dicke Magnetic Structural Phase Transition with Trapped Ions
We study theoretically the collective Ee Jahn-Teller-Dicke
distortion in a system of trapped ions. We focus in the limit of infinite range
interactions in which an ensemble of effective spins interacts with two
collective vibrational modes with U(1) symmetric couplings. Our model is
exactly solvable in the thermodynamical limit and it is amenable to be solved
by exact numerical diagonalization for a moderate number of ions. We show that
trapped ions are ideally suited to study the emergence of spontaneous symmetry
breaking of a continuous symmetry and magnetic structural phase transition in a
mesoscopic system.Comment: 19 pages, 7 figure
Molecular Weight Dependence of Polymersome Membrane Elasticity and Stability
Vesicles prepared in water from a series of diblock copolymers and termed
"polymersomes" are physically characterized. With increasing molecular weight
, the hydrophobic core thickness for the self-assembled bilayers
of polyethyleneoxide - polybutadiene (PEO-PBD) increases up to 20 -
considerably greater than any previously studied lipid system. The mechanical
responses of these membranes, specifically, the area elastic modulus and
maximal areal strain are measured by micromanipulation. As expected
for interface-dominated elasticity, ( 100 ) is found to be
independent of . Related mean-field ideas also predict a limiting
value for which is universal and about 10-fold above that typical of
lipids. Experiments indeed show generally increases with
, coming close to the theoretical limit before stress relaxation is
opposed by what might be chain entanglements at the highest . The
results highlight the interfacial limits of self-assemblies at the nano-scale.Comment: 16 pages, 5 figures, and 1 tabl
Photonic realization of the relativistic Dirac oscillator
A photonic realization of the Dirac oscillator (DO), i.e. of the relativistic
extension of the quantum harmonic oscillator, is proposed for light propagation
in fiber Bragg gratings. Transmission spectra clearly show the existence of
electron and positron bound states of the DO, corresponding to resonance modes
above and below the Bragg frequency, as well as the asymmetry of the energy
spectrum for electron and positron branches
Excitation Enhancement of a Quantum Dot Coupled to a Plasmonic Antenna
Plasmonic antennas are key elements to control the luminescence of quantum
emitters. However, the antenna's influence is often hidden by quenching losses.
Here, the luminescence of a quantum dot coupled to a gold dimer antenna is
investigated. Detailed analysis of the multiply excited states quantifies the
antenna's influence on the excitation intensity and the luminescence quantum
yield separately
Unveiling the near-infrared structure of the massive-young stellar object NGC 3603 IRS 9A with sparse aperture masking and spectroastrometry
Contemporary theory holds that massive stars gather mass during their initial
phases via accreting disk-like structures. However, conclusive evidence for
disks has remained elusive for the most massive young objects. This is mainly
due to significant observational challenges. Incisive studies, even targeting
individual objects, are therefore relevant to the progression of the field. NGC
3603 IRS 9A* is a young massive stellar object still surrounded by an envelope
of molecular gas. Previous mid-infrared observations with long-baseline
interferometry provided evidence for a disk of 50 mas diameter at its core.
This work aims at a comprehensive study of the physics and morphology of IRS 9A
at near-infrared wavelengths. New sparse aperture masking interferometry data
taken with NACO/VLT at Ks and Lp filters were obtained and analysed together
with archival CRIRES spectra of the H2 and BrG lines. The calibrated
visibilities recorded at Ks and Lp bands suggest the presence of a partially
resolved compact object of 30 mas at the core of IRS 9A, together with the
presence of over-resolved flux. The spectroastrometric signal of the H2 line
shows that this spectral feature proceeds from the large scale extended
emission (300 mas) of IRS 9A, while the BrG line appears to be formed at the
core of the object (20 mas). This scenario is consistent with the brightness
distribution of the source for near- and mid-infrared wavelengths at various
spatial scales. However, our model suffers from remaining inconsistencies
between SED modelling and the interferometric data. Moreover, the BrG
spectroastrometric signal indicates that the core of IRS 9A exhibits some form
of complexity such as asymmetries in the disk. Future high-resolution
observations are required to confirm the disk/envelope model and to flesh out
the details of the physical form of the inner regions of IRS 9A.Comment: Accepted to be published in Astronomy & Astrophysics, 13 pages, 14
figure
Spin-Peierls Quantum Phase Transitions in Coulomb Crystals
The spin-Peierls instability describes a structural transition of a crystal
due to strong magnetic interactions. Here we demonstrate that cold Coulomb
crystals of trapped ions provide an experimental testbed in which to study this
complex many-body problem and to access extreme regimes where the instability
is triggered by quantum fluctuations alone. We present a consistent analysis
based on different analytical and numerical methods, and provide a detailed
discussion of its feasibility on the basis of ion-trap experiments. Moreover,
we identify regimes where this quantum simulation may exceed the power of
classical computers.Comment: slightly longer than the published versio
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