Events Archive

Nov
08
2012
A Century of Superfluidity: from Mercury to Neutron Stars, from Nuclei to Ultra-cold Atoms
Nov
08
2012
Analytic Modeling of z>=6 Interstellar Medium
The statistics of newly discovered z>~6 galaxies---their abundance and clustering---have allowed us to study their ensemble properties, but the difficulties inherent in detecting, resolving, and obtaining spectra of these distant, faint objects has prevented a deeper empirical exploration of their internal physics. However, in advance of observatories like GMT and TMT, multi-wavelength observations can be a useful probe of the high-redshift ISM. I will present a novel analytic model for the internal physics of z>~6 galaxies that, when combined with information from galaxy statistics, probes an enormous range of distance scales---from the tens of megaparsec regions over which...
Nov
08
2012
Superflow decay via quantum phase slips in one-dimensional Bose gases
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...
Nov
07
2012
Event-Based Optimal Control of Neurons
Motivated by issues related to treating certain neurological diseases such as Parkinson’s disease by a method called electrical deep brain stimulation, we consider applying optimal control methods to both mathematical models of neurons and in vitro neurons. Patients suffering from Parkinson’s disease experience involuntary tremors that typically affect the distal portion of their upper limbs. It has been hypothesized that these tremors are associated with simultaneous spiking of a cluster of neurons in the thalamus and basal ganglia regions of the brain. In a healthy situation, the periodic firing of neurons is not synchronized, but they can engage in a pathological synchrony...
Nov
05
2012
Topological Excitations in Liquids and Glasses
Condensed matter physics in the 20th Century was developed mostly for crystalline solids, and we know so little about the physics of liquids and glasses.  We do not even know how to describe the structure of these amorphous matters to discuss the structure-properties relationship, even though liquids and glasses are so important to everyday life.  This is because liquids and glasses are condensed matter with high density in which atoms are strongly correlated to each other.  Any theoretical effort runs into a thick barrier of many-body interactions.  To circumvent...
Nov
01
2012
Seeing and Building with Atoms: Adventures in the Nano World
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.
Nov
01
2012
Tidal disruption of a star by a massive black hole in Fermi normal coordinates
I present a new numerical code constructed to obtain accurate simulations of encounters between a star and a massive black hole. The relativistic tidal interaction is calculated in \emph{Fermi normal coordinates} (FNC). This formalism allows the addition of an arbitrary number of terms in the tidal expansion. Although Newtonian hydrodynamics and self-gravity is assumed for the star, there are several significant terms in the expansion that should be retained. I give the relevant orbital post-Newtonian terms. The three-dimensional parallel (MPI) code includes a PPMLR hydrodynamics module to treat the gas dynamics and a Fourier transform-based method to calculate the self-gravity. Results...
Oct
29
2012
Quantum determinism
Oct
25
2012
Spontaneous Rhythms in Nature and Technology
Oct
25
2012
Fast Turnaround 3D Nanolithography using Heated Probes – from Nanofabrication to Directed Assembly
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...

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