Eric Sembrat's Test Bonanza

A novel thermal scanning probe lithography (tSPL) method based on the local removal of organic resist materials has been developed at the IBM Research Laboratory in Zurich [1-3]. A polymeric polyphthalaldehyde resist [2-4] responds to the presence of a hot tip by local material decomposition and desorption. Thereby arbitrarily shaped patterns can be written in the organic films in the form of a topographic relief, constrained only by the shape of the tip. The combination of the fast ‘direct development’ patterning of a polymer resist and the in-situ metrology capability of the AFM setup allows to reduce the typical turnaround time for nano-lithography to minutes.

Patterning rates of 500 kHz have been achieved. For this, the mechanics and drive waveform of the scan stage were optimized, achieving high speed linear scanning with an overall position accuracy of ± 10 nm over scan-ranges and scan-speeds of up to 50 μm and 20 mm/s, respectively. A pre-tension-and-release strategy was used to actuate the cantilever above its resonance frequency of 150 kHz. Fabrication of three dimensional patterns is done in a single patterning step by controlling the amount of material removal at each pixel position. The individual depths of the pixels are controlled by the force acting on the cantilever.

The structuring capability in the third dimension adds an entirely new feature to the lithography landscape and finds applications e. g. in multi-level data storage, nano/microoptic components and directed positioning of nanoparticles. For the latter, shapematching guiding structures for the assembly of nanorods of size 80nm × 25nm have been written by thermal scanning probe lithography [4]. The nanorods were assembled into the guiding structures by means of capillary interactions. Following particle assembly, the polymer was removed cleanly by thermal decomposition and the nanorods are transferred to the underlying substrate without change of lateral position. As a result we demonstrate both the placement and orientation of nanorods with an overall positioning accuracy of ≈ 10 nm onto an unstructured target substrate.

[1] D. Pires, J. L. Hedrick, A. De Silva, J. Frommer, B. Gotsmann, H. Wolf, M. Despont,

U. Duerig, and A. W. Knoll, Science 328, 732 (2010).

[2] A. W. Knoll, D. Pires, O. Coulembier, P. Dubois, J. L. Hedrick, J. Frommer, U.

Duerig, Adv. Mat. 22, 3361 (2010).

[3] P. C. Paul, A.W. Knoll, F. Holzner, M. Despont and U. Duerig, Nanotechnology 22,

275306 (2011).

[4] F. Holzner, C. Kuemin, P. Paul, J. L. Hedrick, H. Wolf, N. D. Spencer, U. Duerig,

and A. W. Knoll, NanoLetters, 11, 3957 (2011).

We present a series of experiments demonstrating how animals stay dry.  These adaptations are necessary for survival in rain and other wet environments.  During flash floods, fire ants weave hydrophobic rafts with their own bodies in order to keep their colonies dry.  We discuss their method of self-assembly and present a model that predicts their construction rate.  To survive raindrop impacts, flying mosquitoes take advantage of their low mass, which prevents drops from splashing upon impact.  The resulting force applied is 100-300 gravities, quite possibly the largest survivable force in the natural world.  Animals much larger than insects employ active mechanisms to shed water.  Mammals across four magnitudes in mass can shake off 70% of the water on their bodies in fractions of a second.  We show that wet mammals shake at tuned frequencies to dry and present a scaling law relating animal size and frequencies required to dry.  In this talk, the audience will learn the basics of modeling and experimentation with surface-tension phenomena.

Homotopy method is being used to explore nonlinear partial differential equation system arising from engineering and physics. This new approach is used to compute multiple solutions of nonlinear PDEs and yields the discretized polynomial systems, which involve thousands of variables. This method can also handle the singularities. This talk will cover the recent progress on nonlinear PDEs such as free boundary problem and hyperbolic conservation law problem.

In recent years, experiments with ultracold atoms [1,2,3,4] have investigated transport properties of one-dimensional (1D) Bose gases in optical lattices and shown that the transport in 1D is drastically suppressed even in the superfluid state compared to that in higher dimensions. Motivated by the experiments, we study superfluid transport of 1D Bose gases. In 1D, superflow at zero temperature can decay via quantum nucleation of phase slips even when the flow velocity is much smaller than the critical velocity predicted by mean-field theories. Using instanton techniques, we calculate the nucleation rate \Gamma_{prd} of a quantum phase slip for a 1D superfluid in a periodic potential and show that it increases in a power-law with the flow momentum p, as \Gamma_{prd} ~ p^{2K-2}, when p is much smaller than the critical momentum [5]. Here, L and K denote the system size and the Luttinger parameter. To make a connection with the experiments, we simulate the dipole oscillations of 1D Bose gases in the presence of a trapping potential with use of the quasi-exact numerical method of time-evolving block decimation. From the simulations, we relate the nucleation rate with the damping rate of dipole oscillations, which is a typical experimental observable [1,3], and show that the damping rate indeed obeys the power-law, meaning that the suppression of the transport in 1D is due to quantum phase slips.  We also suggest a way to identify the superfluid-insulator transition point from the dipole oscillations.

References:

[1] C. D. Fertig et al., Phys. Rev. Lett. 94, 120403 (2005).

[2] J. Mun et al., Phys. Rev. Lett. 99, 150604 (2007).

[3] E. Haller et al., Nature 466, 597 (2010).

[4] B. Gadway et al., Phys. Rev. Lett. 107, 145306 (2011).

[5] I. Danshita and A. Polkovnikov, Phys. Rev. A 85, 023638 (2012).

Rhythms abound in the natural world. Spontaneous rhythmic coordination can be essential: our beating heart cells must synchronize precisely – or else! Sometimes, too much coordination is disastrous: brain seizures can occur as a result of abnormally high levels of synchronous neuronal activity. Examples of spontaneous synchronization are found in every branch of science, from the beautiful nightly light shows of firefly swarms to the synchronized swinging of pendulum clocks. Researchers the world over are trying to understand how coordinated rhythms arise and trying to discover ways to control them. An array of applications awaits: faster computers, brighter lasers, collision- avoiding cars; new strategies for treating heart and brain disorders; even an end to the devastation of periodic locust swarms.

Do you think Physics is only about stars and mad scientists? Come to this event and you will discover a new Physics world where fundamental physics knowledge is used “as simply as possible but not simpler” to build atom by atom the technology of future.  Come and learn how we make the smallest electronic circuits in the world, how we can build devices that power your cell phone while you walk in the streets, or how we pull single DNA molecules to understand the secrets of life.

Advances in microscopy have enabled measurements in living cells, but there is a wealth of biologically relevant dynamical information contained in experimental data that has not been utilized.  Existing analysis methods either coarse grain too much or cannot overcome some technical challenges inherent to in vivo measurements. The importance of more fully utilizing information “hidden” in noisy 3D in vivo measurements will be emphasized in several problems.  In this talk, I demonstrate how recent advances in time series analysis can be used to estimate stochastic differential equations (SDEs) and construct hypothesis tests checking the consistency of a fitted model with a single experimental trajectory. The inferred SDE parameters change in a statistically significant fashion over the lifetime of a single trajectory, so methods capable of rigorous statistical inference checking all SDE model (and measurement noise) assumptions using only one time series are valuable.   Analyzing a single trajectory is important for quantitatively identifying heterogeneity in noisy complex systems.  The methods discussed offer new tools for quantitatively probing molecular traffic in the cytoplasm and also enable new discoveries. Although the results presented are centered around the analysis of experimental  mRNA in live yeast cells (Saccharomyces Cerevisiae), the work is also relevant to tracking groups of particles in crowded, noisy, complex environments.

Joseph Ford saw beauty in "Chaos" and the potential for ``villainous chaos" to be used in a constructive manner. His ideas have proved prescient. The talk will focus mainly on how chaotic dynamics may have played a key constructive -- rather than destructive -- role in shaping certain features of the Kuiper belt: in particular, the formation and properties of binary objects in the transneptunian part of the Solar System. Kuiper belt binaries stand out from other known binary objects in having a range of peculiar orbital and physical properties which may, actually, be the fingerprint of chaos in the primordial Kuiper belt. Understanding how these remote binaries formed may shed light on the formation and evolution of the Solar System itself.

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EN-US;mso-bidi-language:AR-SA">Over the last several years the field of ferroelectric and multiferroic oxides has been experiencing a significant revival. This is largely due to recent experimental advances allowing characterization of their functional properties down to the nano- and atomic scale. Specifically, Piezoresponse Force Microscopy (PFM) proved to be an indispensable tool for high-resolution characterization of ferroelectrics. Although, the standard implementation of this technique has been around for almost 15 years, recent years have witnessed the development of advanced modes of PFM such as resonance-enhanced PFM, stroboscopic PFM, switching spectroscopy PFM and so on. This lecture will focus on application of the advanced PFM modes to investigation of the dynamic switching and electronic properties of ferroelectric nanostructures. This will include critical polarization behavior in single-crystalline mso-bidi-font-family:Times-Roman;mso-ansi-language:EN-US;mso-fareast-language:
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mso-bidi-language:AR-SA">he structural disorder effect on domain switching dynamics in ferroelectric polymers will be discussed as well.

The detection of gravitational waves from the inspiral of a neutron star or stellar-mass black hole into an intermediate-mass black hole (IMBH) promises an entirely new look at strong field gravitational physics. Gravitational waves from these intermediate-mass-ratio inspirals (IMRIs), systems with mass ratios from 10:1 to 100:1, may be detectable at rates of up to a few tens per year and will encode a signature of the central body's spacetime. Direct observation of the spacetime will allow us to use the "no-hair" theorem of general relativity to determine if the IMBH is a Kerr black hole (or some more exotic object, e.g. a boson star). In this talk, I will discuss the prospects for constraining the central body's mass-quadrupole moment in Advanced LIGO, and the potential to detect large, non-Kerr compact objects. I will also discuss the current status of LIGO, and prospects for parameter estimation in the advanced detector era, including the results of a recent blind injection challenge.