Colloquia held Fall Semester, 2005
 

November 15, 2005
Dr. Juyang Huang
Department of Physics
Texas Tech University
"Predicting the Behavior of Cholesterol: The Power of Thermodynamics"
Cholesterol is the most interesting and important lipid molecule in cell membranes. One fascinating story is that cholesterol molecules form Super Lattices in lipid membranes, i.e., they form symmetrical crystal-like distributions in a 2-dimensional fluid without any chemical bonds. Despite decades of experimental and theoretical work, researchers still disagree on how cholesterol interacts with other membrane molecules. We proposed a physical model (The Umbrella Model), which explains the key cholesterol-lipid interactions. Thermodynamic analysis and Monte Carlo simulations based on the model revealed detail mechanism of Super-Lattice formation. A number of new experimental measurements, specifically designed to test the model, show excellent agreement with the predictions of the model.
 

November 8, 2005
Dr. Girish S. Agarwal
Department of Physics
Oklahoma State University
"Quantum Entanglement among Qubits to Mesoscopic and Macroscopic Systems"
Entanglement is a great resource for quantum information and quantum computing. Entanglement makes possible novel quantum communication protocols and is at the heart of quantum cryptography and quantum teleportation. It is important to understand how to generate entanglement between different systems. In this talk we discuss how to generate entanglement between a variety of systems including mesoscopic systems. We discuss various ideas from cavity QED and collective dynamics of atoms. The well-known Dicke states of a system of N atoms exhibit very strong quantum correlations and entanglement, although it is not yet known how to produce such states for a multi-particle system. The dynamics of a collective system can be studied by a master equation, which shows how quantum entanglement in a collective system develops in time and how entanglement can be transferred from one system to another. The application of a coherent drive further enables us to have a control on quantum entanglement. These ideas can be extended to produce entanglement between mesoscopic systems, such as two Bose condensates or two nano cant levers sharing interaction with a Cooper pair box.
 

November 1, 2005
Dr. Paolo Grigolini
Center for Nonlinear Science
Department of Physics
University of North Texas
"Complexity in Physics: The Living State of Matter"
We discuss two examples of physical systems exhibiting emergent properties that require a new paradigm, viz, blinking quantum dots and random growth of surfaces. Both phenomena are characterized by renewal aging, a property that is not equivalent to change in time: Renewal aging is rather determined by the lack of equilibrium. Renewal aging corresponds to individual trajectories with abrupt bursts, separated by long quiescent periods. Each burst resets to zero the system's memory, thereby creating renewal. The non-exponential distribution of quiescence times generates aging. The system's response to external perturbation depends on the time between preparation and perturbation. Although the response to perturbation cannot be predicted from traditional first principles, the assumption of a renewal condition allows us to make an exact theoretical prediction. We show that external perturbations have the effect of breaking the renewal aging, and thus turning it into a traditional form of memory. We propose a method to analyze experimental data that will assess whether a generic system fits fully the condition of renewal aging, or whether it lives in a state where renewal aging is combined with the traditional forms of memory.
 

October 25, 2005
Dr. Ravi Prasad
Vani-Vihar Institute of Nuclear Physics
Utkal University, Bhubaneswar, India
"Radio Carbon Dating and Trace Element Analysis by Accelerator Mass Spectrometry"
 

October 18, 2005
Dr. Joseph M. Izen
Physics Program
University of Texas at Dallas
"When Spectroscopy Fails"
A charmonium meson is a particle made of a charm quark and an anti-charm quark. It is the "hydrogen atom," or more correctly the "positronium" of meson spectroscopy. Historically, the observation of two charmonia, the J/psi(1S) and the psi (2S), was a crucial piece of evidence that confirmed the existence of quarks. Many charmonium excitations have since been identified by annihilating electrons and positrons or protons and antiprotons with just enough energy to produce a charm-anticharm system. Charmonium spectroscopy has been the primary yardstick for measuring the radial dependence of the strong force. After nearly three decades of routine charmonium spectroscopy, a fly has lodged itself in the ointment. The B-factories, which annihilate beams of electrons and positrons at over three times the energy for threshold charmonium production, have developed novel techniques to observe charmonia. These experiments are finding states with masses where charmonia were not expected, culminating this past summer in the discovery of the Y(4260) which may be the most exotic of all the new states. The evidence for the Y(4260), and theoretical speculation regarding its nature will be presented.
 

October 11, 2005
Dr. Wolfgang Schleich
Abteilung fur Quantenphysik
University of Ulm, Germany
"Tailored Matter for Rotatikon Sensors in Space"
The enormous progress in atom optics and, in particular, in the physics of cold atoms highlighted by the phenomenon of the Bose-Einstein condensation has opened new avenues in the tests of general relativity and other foundations of physics. For example, the unsurpassed accuracy of atom interferometry enables one to measure new aspects of the elusive Lense-Thirring effect. Unfortunately, due to the non-vanishing mass of atoms the accuracy of atom interferometers cannot be increased indefinitely. However, by moving into space we can enhance the sensitivity by orders of magnitudes. Moreover, quantum mechanics provides new tools to push these limits even further by employing the concept of entanglement. In this talk we will review the status of key experimental tools in quantum and atom optics and suggest various experiments to test the foundations of physics in space.
 

October 4, 2005
Dr. Nitant Kenkre
Department of Physics
University of New Mexico
"Theory of the Spread of Epidemics: Simple Statistical Mechanical Considerations"
Our recent work in the theory of the spread of epidemics such as the Hantavirus and the West Nile Virus will be described. The work involves Fisher-type equations in various modified forms, the formation of spatio-temporal patterns related to observed refugia, diffusion of infection-spreading animals in confined areas (home ranges) and description via Fokker-Planck treatments, Master equations, and extended random walks. Applications to observations in several locales, including in Panama and in New Mexico will also be mentioned. This research is supported in part by the NSF, NIH, and DARPA.
 

September 27, 2005
Dr. Donald H. Kobe
Department of Physics
University of North Texas
"Quantum Chaos from Bohmian Trajectories"
The signature of classical chaos is that two trajectories, initially very close, separate exponentially from each other with time. In standard quantum mechanics there are no trajectories, so this criterion cannot be used. In the Bohmian formulation of quantum mechanics, however, there are quantum trajectories determined by the classical potential and a quantum potential. After reviewing classical chaos and the Bohmian formulation, I will describe our work in applying quantum trajectories tot he quantum kicked rotor. I will show our results for both classical and quantum chaos in the kicked rotor.
 

September 20, 2005
Dr. Guillermo Gonzalez
Department of Physics and Astronomy
Iowa State University, Ames, Iowa
"Life in the Universe"
Habitability, or conditions conducive to life, varies dramatically with location and time in the universe. This was recognized centuries ago, but only in the last few decades have astronomers begun to systematize the study of habitability. The introduction of the concept of habitable zone was key to progress in this area. The habitable zone concept was first applied to space around a star, but more recently other, vastly broader, habitable zones have been proposed. I will give a general talk about how this concept relates to possible life in the universe and how it relates to the "privileged Planet" hypothesis.
 

September 13, 2005
Dr. Floyd McDaniel
Department of Physics
University of North Texas
"Research Opportunities in the Physics Department at UNT"
Different research groups in the Department of Physics at the University of North Texas will make short presentations to inform students and faculty about their research activities.
 

September 20, 2005
Dr. Guillermo Gonzalez
Department of Physics & Astronomy
Iowa State University
Habitable Zones in the Universe
Habitability varies dramatically with location and time in the universe. This was recognized centuries ago, but only in the last few decades have astronomers begun to systematize the study of habitability. The introduction of the concept of habitable zone was key to progress in this area. The habitable zone concept was first applied to space around a star, now called "Circumstellar Habitable Zone." Recently, other, vastly broader, habitable zones have been proposed. I will review the present state of research on habitable zones and discuss how it relates to the "Privileged Planet" hypothesis.
 

September 27, 2005
Dr. Donald Kobe
Department of Physics
University of North Texas
"Quantum Chaos from Bohmian Trajectories"
The signature of classical chaos is that two trajectories, initially very close, separate exponentially from each other with time. In standard quantum mechanics there are no trajectories, so this criterion cannot be used. In the Bohmian formulation of quantum mechanics, however, there are quantum trajectories determined by the classical potential and a quantum potential. After reviewing classical chaos and the Bohmian formulation, I will describe our work in applying quantum trajectories to the quantum kicked rotor. I will show our results for both classical and quantum chaos in the kicked rotor.
 

October 4, 2005
Dr. Nitant Kenkre
Department of Physics
University of New Mexico-Albuquerque
"Theory of the Spread of Epidemics: Simple Statistical Mechanical Considerations" 
Our recent work in the theory of the spread of epidemics such as the Hantavirus and the West Nile Virus will be described. The work involves Fisher-type equations in various modified forms, the formation of spatio-temporal patterns related to observed refugia, diffusion of infection-spreading animals in confined areas (home ranges) and description via Fokker-Planck treatments, including in Panama and in New Mexico will also be mentioned. This research is supported in part by the NSF, NIH, and DARPA.