Day 1 :
Arizona State University, USA
Keynote: In-situ electron paramagnetic resonance studies of paramagnetic point defects in superconducting microwave resonators
Time : 9:00-9:30
Nathan Newman is a Professor of Solid State Sciences and is a faculty member in the Materials Program at Arizona State University. His research interests focus on the investigation of novel solid-state materials for microwave, photonic and high-speed applications. His current work involves synthesis, characterization and modeling of novel superconductor junctions and materials, III-N semiconductors, low loss dielectrics for microwave communication, and novel photovoltaic material. He is an author and co-author of over 200 technical papers, has 12 patents, has an h-index over 40 and his papers have been cited over 5,000 times. He has received the IEEE Van Duzer Award, is a Fellow of the IEEE and the American Physical Society, and has won Faculty Teaching Awards at Northwestern University and Arizona State University. He also serves as an Associate Editor for Materials in the IEEE Transactions of Applied Superconductivity and has served as the Chair of the US Committee on Superconductor Electronics and ASU’s LeRoy Eyring Center for Solid State Sciences.
The physical nature and concentration of paramagnetic point defects in the dielectrics of superconducting planar microwave resonators have been determined using in-situ electron paramagnetic resonance spectroscopy. To perform this work, the quality factor of parallel plate and stripline resonators was measured as a function of the magnitude of a magnetic-field applied parallel to the electrode surfaces. YBa2Cu3O7-d thin film electrodes proved to be a preferred choice over Nb and MgB2 because they are readily available and have a small surface resistance (Rs) up to high temperatures (~77 K) and magnetic fields (i.e., <1 T). Stripline resonators with a widely used high performance microwave dielectric, Co2+ doped Ba(Zn1/3Nb2/3)O3, are shown to have losses dominated by d-electron spin-excitations in exchange-coupled Co2+ point-defect clusters, even in the absence of an applied magnetic field. A significant enhanced microwave loss in stripline and parallel plate resonators is found to correlate with the presence of paramagnetic Mn dopants in Ba(Zn1/3Ta2/3)O3 ceramics and dangling bond states in amorphous Si thin films, although the identification of the dominant loss mechanism(s) in these dielectrics requires further investigation.
University of Massachusetts, USA
Time : 9:30-10:00
D V G L N Rao had a brilliant academic record at Andhra University where he got the BSc (Honors), MSc and DSc degrees and also taught for two years. He spent two years each at Duke and Harvard Universities as Post-doctoral Fellow. He has been teaching at the University of Massachusetts, Boston since 1968 where he is currently Distinguished Professor in the Physics Department. He was elected Fellow of the American Physical Society, Division of Laser Science in 2010 in recognition of a long record of significant contributions to the nonlinear optics of organic materials and their applications to optical power limiting, Fourier phase contrast microscopy and medical image processing. He published over 120 papers in peer reviewed prestigious journals like Physical Review Letters, Applied Physics Letters, Optics Letters, etc. He is covering research areas like nonlinear optics, magnetic resonance, microwave absorption, optical Fourier techniques for breast cancer diagnostics, phase contrast and multimodal optical microscopy, etc. He holds 10 patents and one of these on Fourier phase contrast microscopy is recently licensed to industry for marketing the technology.
We have been working on basic nonlinear optics of the protein complex Bacteriorhodopsin (bR) thin polymer films with milliwatt cw lasers. The unique feature of this material is its flexibility. Absorption of a visible photon by bR triggers the photo cycle, starting from the initial B state to the relatively long lived M state via short lived intermediate states. It can revert to the initial B state thermally in milliseconds via short lived intermediate states or can go back directly to B state within nanoseconds by shining blue light. Both life times can be altered by orders of magnitude using chemical methods or genetic mutation. The process of switching between B and M states (chemical isomers) can go in both directions depending on wavelength, intensity and polarization of the incident light offering a variety of possibilities for manipulating amplitude, phase and polarization. Over the years we studied the basic nonlinear optics-four wave mixing, phase conjugation, photo induced anisotropy, etc. We successfully exploited the unique properties for many applications like: All optical switching, modulation, computing, information processing, power limiting for laser eye protection, medical image processing, transient Fourier holography, etc. More recently, we are focusing on optical Fourier techniques for early detection of micro calcifications in mammograms for breast cancer diagnostics. We also developed an innovative technique of Fourier phase contrast microscopy and multimodal optical microscopy for live cell imaging of biological samples. I will present some highlights of our work with particular reference to development of inexpensive biomedical devices.
Kindai University Technical College, Japan
Time : 10:00-10:30
Rikio Konno has completed his PhD from University of Tokyo and Post-doctoral studies from Tsukuba University. He is the Science Section Head of Kindai University Technical College, a famous college based on Kindai University in Japan. He has published more than 25 papers in reputed journals.
We investigated thermal expansion of ferromagnetic superconductors below the superconducting transition temperature and that of antiferromagnetic superconductors below the Neel temperature within the mean-field approximation. Both of them were based on the free energy derived from microscopic single band models. Takahashi’s method was applied to the free energy in order to obtain thermal expansion. In the ferromagnetic superconductors, the superconducting gap of the A2 phase in liquid 3He and that of the line node were used. We found that an anomaly of the thermal expansion exists in the vicinity of the superconducting transition temperature. In the antiferromagnetic superconductors, the isotropic singlet superconducting gap was used. We found that the jump of thermal expansion appears at the superconducting transition temperature. The thermal expansion has an exponential behavior at very low temperatures. The thermodynamic Gruneisen’s relation is automatically satisfied in both the cases.