Research

My Resume
International Superconductivity Technology Center
Luce Scholars Program

The end goal of my research was to investigate the electron pairing mechanism responsible for high-temperature superconductivity in copper oxide superconductors. This study focused on infinite-layer (IL) compounds, which have the simplest crystalline structure of all superconducting cuprates. I attempted to fabricate single crystals of infinite-layer compounds ACuO₂ (where A=Sr, Ca is a cation) and/or Sr_xR_1-xCuO₂ (where R=Nd, La). Since the heyday of superconductivity in the late 1980s, researchers have tried to fabricate single crystals of this compound for STM studies to reveal any atomic-sized defects, charge density modulations, and other fundamental properties that could explain the underlying mechanism for high-temperature superconductivity. However, mostly because no phase diagram has been devised that delineates the formation of these compounds, such attempts have been unsuccessful. Also, high pressures (P) and temperatures (T) are required to synthesize such compounds. I thoroughly experimented with adjusting parameters such as crucible type, oxygenation, pressure, temperature, synthesis time, and self-fluxes. Though I too was unable to produce single crystals, I hope that my thorough data will eventually contribute to the creation of a P-T-x phase diagram.

Documentation
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California Institute of Technology: Condensed Matter Physics
Senior Thesis (and summer research continuation): SNS Junctions based on MgB₂ Thin Films

A high-precision, non-destructive fabrication process was developed for superconducting-normal- superconducting (SNS) junctions of magnesium diboride. Junctions of weak-link dimensions 100 nm x 150 nm were fabricated using photolithography, ion milling, and a focused ion beam. The advantageous properties of MgB₂, like s-wave pairing symmetry, long coherence length, fully gapped Fermi surface, and relatively high Tc=39 K, are expected to yield high critical currents (I_c) and large I_cR_n products (where R_n is the junction resistance) in the MgB₂-based devices and are quite promising for applications in high-frequency electronics. In this study, preliminary results are gathered for SNS junctions fabricated on c-axis oriented MgB₂ thin films.

Documentation
- Caltech Senior Thesis
California Institute of Technology: Applied Physics
Teaching Assistant for the Applied Physics senior lab (APh 77)

APh 77 is a senior laboratory course of selected experiments chosen to familiarize students with laboratory equipment, procedures, and characteristic phenomena in plasmas, fluid turbulence, fiber optics, X-ray diffraction, microwaves, high-temperature superconductivity, black-body radiation, holography, and computer interfacing of experiments. I managed the superconductivity and x-ray diffraction labs.
Max Planck Institute for Physics: H1-Group

At Max Planck, I assisted in writing LABVIEW and C++ programs for upgraded H1 LAr Calorimeter Trigger test electronics. (The Mellon Fellowship funded this internship.)
Harvard-Smithsonian Center for Astrophysics: High Energy Astrophysics

Involved in computational astrophysics, I analyzed Chandra data. My computer was too slow, I was only given an office for about 4 hours each day, and my adviser did absolutely nothing to remedy the situation, despite my complaints. However, this internship was not at all a waste of time. I was able to periodically work with an experimental astrophysicist who provided knowledgeable discussion about condensed matter physics. Through this work, I experienced working in a clean room for the first time, and working with potential telescope coatings, namely profilometry tests on these sensitive films. During my time in Boston, I met the head of the Center, Dr. Shapiro, and one of the brightest minds in the field of superconductivity, Dr. Tinkham of Harvard University. Since my internship did not work out as initially hoped, I was able to fruitfully devote my free time to working on my team's experiment for the Reduced Gravity Student Flight Opportunities program, which we flew in August.
California Institute of Technology/ NASA's Jet Propulsion Lab
NASA Reduced Gravity Student Flight Opportunities Program

News Articles and Press Releases
Los Angeles Times, September 6, 2001
Caltech Press Release, September 6, 2001
"Engineering & Science" Magazine, 2001 Issue No. 2

In January 2001, I organized and led a team that participated in the NASA Reduced Gravity Student Flight Opportunities Program. Through this program, we built an experiment that we later ran on NASA's KC-135 microgravity airplane.
ZBLAN, a member of the heavy-metal fluoride family of glasses, transmits light with attenuation rates much lower than those of silica-based materials. Microspheres of ZBLAN therefore have the theoretical potential to form fiber optic transmission lines with very high transmission rates. Experiments, however, have shown that the presence of gravity during the ZBLAN glass transition phase causes crystallization, degrading the optical properties of the glass. Dr. Dennis Tucker of NASA's Marshall Space Flight Center first showed in 1998 that very little crystallization occurs in ZBLAN fibers fabricated in a microgravity environment.

Microspheres of doped and undoped ZBLAN were fabricated in microgravity. Their optical properties were to be compared with microspheres fabricated in a 1g environment. Silica-based fibers were produced as a control. The optical transmission properties of ZBLAN can be deduced from the longevity of whispering gallery modes induced in microspheres of the glass. Fabricating spheres promises a much simplifed means of measuring the attenuation of ZBLAN since no fiber needs to be pulled in 0g. This first trial of the experiment was troubled by surface contamination and material breakdown; the resulting microspheres were too poor in quality to be used as light resonators. The second phase resulted in a sphere fabrication procedure to produce more pure, better resonators.

Documentation
National University of Singapore: Center for Magnetic and Superconducting Materials

During my short internship in Singapore, a wonderful graduate student from China, Dr. Chen Ping, first introduced me to experimental techniques for fabrication and analysis of superconducting devices, like photolithography, scanning electron microscopy, atomic force microscopy, and molecular beam epitaxy. Additionally, I first learned the theory behind DC and AC Jospehson junctions and superconducting quantum interference devices (SQUIDS). (The Mellon Fellowship funded this internship.)
Raytheon Infrared Operations: Test Engineering in Astrophysics

As a test engineer, I tested infrared focal plane arrays for astronomy projects, like SIRTF.

Documentation
NASA Ames Research Center: Test Engineering
Education Associates Program

As a test engineer, I assisted in developing and testing infrared and submillimeter detectors and the associated read-out electronics. (For example, smaller resistors have more non-linear, less predictable IV curves. However, often, large resistors can not be used due to size constraints.) Further, I prepared cryogenic instrument dewars for testing. I designed and fabricated electronic circuits, optical and mechanical components for in-house use and the restoration of a class IV CO₂ laser. This job was my first experience using vacuum systems and cryogenics.
California Institute of Technology / NASA's Jet Propulsion Lab: Astrobiology
Summer Undergraduate Research Fellowship
Microbial Characteristics of Mono Lake
Microbial life in Mono Lake, a hypersaline and highly alkaline body of water located in the eastern Sierra Nevada Mountains in northern California, is considered a possible analog to ancient Martian lakes. Similar to Mono Lake, Mars is postulated to have contained lakes in enclosed basins of high salinity, enhanced by the dessication of the Martian environment. Enclosed basin lakes often embody a high concentration of minerals, thereby providing sustenance for rich microbial ecosystems. Studying extreme environments on Earth, like Mono Lake, teaches us how experiment on other planets. It further helps us find new methods for detecting evidence of life. Additionally, extremophile studies provide insight into the plasusibility of life in specific regions of Mars, and the characteristics of such organisms. In this study, the microbial diversity of Mono Lake is analyzed by culturing of a set of bacterial colonies in media of varying alkalinity and salinity to determine the range of conditions in which conlonies can procreate. The study is then telescoped to an in-depth characterization of particular specie discovered to grow in a wide range of pH environments.

Documentation
- SURF research paper and presentation
- "Microbial Characteristics of Mono Lake Sediment and Descriptions of Nobel Alkalohalophiles" K. Venkateswaran, M. Hernandez, E. Cardenas, C. Paniagua, S. Eley, B. Lanoil, R. Kern, K. Nealson. California Insitute of Technology and Jet Propulsion Laboratory , Pasadena, CA 91106 contact: K. Venkateswaran, kjvenkat@jpl.nasa.gov
North Carolina A&T State University: Mechanical Engineering
NASA SHARP Plus Program (now NASA SHARP)
Structural Health Monitoring: Detecting Damage in Composite Material Panels Using Vibration Measurements
Damage detection is a vital part of the maintenance of different structures and is especially important for Resuable Launch Vehicles (RLV). Non-destruction evaluation (NDE) methods for location and quantification of damage are essential. To test the feasibility of the Transmittance Function Monitoring (TFM) method as a damage detection technique, damage in flat and curved 48 in. by 48 in. composite panels is evaluated. Each panel system is composed of two 0.25 in. thick plates joined by symmetrically placed bolts. Delamination is simulated by loosening bolts; piezo-electric actuators excite vibrational modes in the structure. Data from the healthy plate condition is compared to data from the damaged plate condition to detect the extent and location of damage. The transmittance functions are calculated using the cross and auto power spectra of the accelerometers.

Documentation