Karl Saunders, Assistant Professor Department of Physics Calif. Polytechnic State Univ. San Luis Obispo, CA 93407 805.756.1696 (office) 805.756.2435 (fax) ksaunder@calpoly.edu updated Oct 1st 09  RESUME You can download my resume from the attachments section at the bottom of the page. TEACHING In fall quarter 09 I am teaching Physics 121 (College Physics IA). OTHER CLASSES THAT I HAVE TAUGHT
RESEARCH STUDENTS: The availability of research positions and projects will vary over time. If there is a research topic or project that you would like to work on please get in touch with me. If you just want to learn more or chat about my research interests, let me know. PUBLICATIONS: My condensed matter publications can be accessed here and my pattern formation publication can be accessed here. PRIMARY RESEARCH INTERESTS A Portable New Chemical/Biological Sensor This theoretical project will investigate the design and feasibility of a novel liquid crystal sensor that could be used to detect the presence and amount of foreign biological and/or chemical airborne agents. Such a sensor would have the advantage of being very portable. As such could have particular value in detecting biological or chemical weapons in the field of military operations. It would also be of use in a rapid response to a chemical or biological terrorist attack. The device would operate on the basic principal that when certain types of molecules bind to a liquid crystal molecule, the conformation of the liquid crystal molecule changes. This would in turn lead to a change in the overall arrangement of the liquid crystal, which could be detected using polarized light. Interested? Students interested in working with me on this should be mathematically proficient. Landau Theory for de Vries Smectic Liquid Crystals De Vries smectic liquid crystals are a new type of liquid crystal that exhibit very unusual behavior- the smectic A phase is more ''disordered'' the closer it is (e.g. in temperature) to the more ''ordered'' smectic C phase. There are also several associated features that make these liquid crystals very fun to study. Their behavior is significant both scientifically and technologically for liquid crystal displays. I am currently developing a Landau theory that models de Vries liquid crystals. Landau theory is a powerful theoretical tool from Condensed Matter physics that can be used to study phase transitions. This theoretical project is being carried out in conjunction with an experimental investigation being carried out by Dr Jonathan Fernsler's group. Interested? Students interested in working with me on this should be mathematically proficient. Thermal physics would be useful but is not crucial. Pattern Formation in Nonlinear Optical Systems Pattern formation is a relatively new and cross disciplinary field of study. It is seen in physics (e.g. Rayleigh-Benard convection), chemistry (e.g. reaction-diffusion systems) and biology (e.g animal coats). Nonlinear optical systems display a very wide range of ''controllable'' pattern formation behaviors which makes them wonderful to study. I am interested in the theoretical analysis of these systems and I have been collaborating with Drs Sharpe and Sungar who have set up such a system here at Cal Poly. Visit the lab here. One interesting feature that we studied was the control of patterning through the periodic alternation of a parameter (laser intensity). We recently published a paper on this work I am currently extending the theoretical analysis we did for this particular system to more general systems. In the near(ish) future I would like to develope a model for the fluctuations and "elasticity" of such systems- there are reasons to think that they could be quite fundamentally different from condensed matter systems. Of related interest is how nonlinear optical systems are affected by "disorder" and pinning. Interested? Mathematical enthusiasm would be important for students working on this research. SECONDARY RESEARCH INTERESTS The Dynamics of Driven Disordered Extended Media - "Depinning" Everyday examples of extended media are sheets of rubber or jello. More technical sounding examples are charge density waves (CDWs) in anisotropic conductors and vortex lattices (VLs) in type II superconductors. Disorder for sheets of rubber or jello could be a rough surface like very coarse sandpaper, while for CDWs and VLs it takes the form of ionic and magnetic impurities. When a small driving force is applied to the medium, the dirt will act to prevent it from moving or, in other words, it will pin it. As with friction, once a large enough force is applied the medium will start to move or depin. The main element of my research is the nature of this depinning. Is it sudden or gradual? Does it stop moving at the same force it started moving? Do CDWs and VLs depin more like rubber or jello? Vortex Lattices in Ferromagnetic Superconductors It has been theorized that in these novel type II superconducting materials, vortex lattices can ''spontaneuously'' (i.e. without an external magnetic field) develop. It has been shown that the elastic properties of such vortex lattices are just like those of a columnar liquid crystal. I am planning to study the way in which these types of vortex lattices "depin" (see above). Liquid Crystals I am interested in many different types and aspects of liquid crystals, in particular how they are affected by disorder. Interested? My interest and research in these areas is theoretical in nature. Students interested in working with me on this should be mathematically proficient. Thermal physics would be useful but is not crucial. EXPERIMENTAL LIQUID CRYSTAL PROJECTS There are other Cal Poly Physics faculty doing experimental work on liquid crystals. Dr. Saimir Barjami is conducting a calorimetric investigation of de Vries type materials. Dr. Jonathan Fernsler is conducting an optoelectrical investigation of de Vries type materials. Dr. Matt Moelter plans to measure the velocity and attenuation of sound passing through liquid crystals. Liquid crystals can be thought of as being anistropic liquids and this anistropy makes there ultrasonic properties very interesting. MISCELLANEOUS PROJECTS The Physics of Balancing a Soda Can In a nice demonstration a soda can containing the right amount of liquid can be balanced on its edge (see figure 1 below). Try it! This ongoing project involves analyzing the physics of this demonstration. While the conceptual physics is straightforward (gravitational torque), it turns out that there is quite a lot going on with some unexpected details. So far, this project has been theoretical in nature so far but there are several experimental components that could be explored. Interested? The theoretical side of this project is quite mathematical. Students interested in working on this should be mathematically proficient and experience with Maple would be useful.  Figure 1: Balancing a soda can Nonlinear Dynamics of a Spinning Magnet This project would be an extension of a lab from Phys 417 (Nonlinear Dynamics). A permanent magnet that is free to spin and is placed between two Helmholtz coils shows some very interesting nonlinear behavior. This behavior can be modeled by a relatively simple nonlinear differential equation that yields complex behavior. In this project would be both theoretical (mathematically modeling the system) and experimental (comparing it to the real system) in nature. Interested? The theoretical side of this project is will involve numerical simulation of a differential equation and experience with Maple/Matlab would be useful. |