The high temperature superconductors which were discovered in 1986 still continue to pose major challenges to scientists. Not only is the mechanism for superconductivity not known, but the nature of the superconducting state and the motion of vortices continue to be debated intensely. We study the microwave response of superconductors, both for understanding the nature of superconductivity, the dynamics of vortices and for practical applications in microwave devices.

The principal areas of our research are:

  • Fundamental measurements and analysis of the penetration depth and surface impedance of superconductors, with a view to understanding the pairing state, the quasiparticle spectrum and the gap parameter
  • Vortex dynamics at high (rf and microwave) frequencies to obtain quantiative measurements of parameters such as pinning force constants, vortex viscosity, critical fields, melting and vortex glass transitions
  • Flux penetration and critical state dynamics
  • Josephson type nonlinear phenomena at microwave frequencies
  • Development of novel measurement techniques, such as the “hot finger” cavity method to measure surface impedance, tunnel diode technique of measuring penetration depth, patterned film structures to study vortex dynamics, modulated microwave absorption

The materials we study are the cuprate High Tc superconductors, borocarbides, and organic superconductors.

Our work in Superconductivity is supported by:

  • National Science Foundation
  • Division of Materials Research and Division of Electrical and Communications Systems, Rome Laboratory, Hanscom AFB (an AFOSR lab)

Related Publications

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Lu, WT; Zeng, Weiqiao; Sridhar, S

Duality between quantum and classical dynamics for integrable billiards Journal Article

In: Physical Review E, vol. 73, no. 4, pp. 046201, 2006.

Abstract | Tags: Quantum Chaos

Lu, WT; Sridhar, S

Long range correlations among the eigenvalues of polygonal billiards and Riemann zeros Journal Article

In: APS, vol. 2004, pp. D19–004, 2004.

Abstract | Tags: Quantum Chaos

Lu, WT; Sridhar, S

Correlations among the Riemann zeros: Invariance, resurgence, prophecy and self-duality Journal Article

In: arXiv preprint nlin/0405058, 2004.

Abstract | Tags: Quantum Chaos

Lu, WT; Sokoloff, JB; Sridhar, S

Classical physics, including nonlinear media and photonic materials-Refraction of electromagnetic energy for wave packets incident on a negative-index medium is always negative Journal Article

In: Physical Review-Section E-Statistical Nonlinear and Soft Matter Physics, vol. 69, no. 2, pp. 26604–26604, 2004.

Tags: Quantum Chaos

Wen-tao, Lu T; Sridhar, Srinivas; Zworski, Maciej

Fractal Weyl laws for chaotic open systems Journal Article

In: 2003.

Abstract | Tags: Quantum Chaos

Pradhan, Prabhakar; Lu, Wentao T; Sridhar, S

Statistics of the Eigenfunctions of Chaotic and Disordered Quantum Systems: A Disordered Tight Binding Model Calculation Inproceedings

In: APS Meeting Abstracts, 2003.

Abstract | Tags: Quantum Chaos

Lu, WT; Sridhar, Srinivas; Zworski, Maciej

Fractal Weyl laws for chaotic open systems Journal Article

In: Physical review letters, vol. 91, no. 15, pp. 154101, 2003.

Abstract | Tags: Quantum Chaos

Sato, Daisuke; Lu, Wentao; Pradhan, Prabhakar; Sridhar, Srinivas

Spectral statistics of microwave disordered billiards Inproceedings

In: APS Meeting Abstracts, 2003.

Abstract | Tags: Quantum Chaos

Dhar, Abhishek; Rao, Madhusudhana D; Sridhar, S; others,

Isospectrality in chaotic billiards Journal Article

In: Physical Review E, vol. 68, no. 2, pp. 026208, 2003.

Abstract | Tags: Quantum Chaos

Sridhar, S; Lu, WT

Sinai billiards, Ruelle zeta-functions and Ruelle resonances: microwave experiments Journal Article

In: Journal of statistical physics, vol. 108, no. 5-6, pp. 755–765, 2002.

Abstract | Tags: Quantum Chaos

Pradhan, Prabhakar; Sridhar, S

From chaos to disorder: Statistics of the eigenfunctions of microwave cavities Journal Article

In: Pramana, vol. 58, no. 2, pp. 333–341, 2002.

Abstract | Tags: Quantum Chaos

Sridhar, S; Lu, WT

Sinai billiards, Ruelle zeta-functions and Ruelle resonances: microwave experiments. e-print Journal Article

In: 2002.

Abstract | Tags: Quantum Chaos

Sinai, Ya G; Young, Lai-Sang; Sridhar, S; Lu, WT; van Beijeren, Henk; Dorfman, JR; Jakšic, V; Pillet, CA; Gallavotti, G; Lebowitz, JL; others,

Some Ill-Formulated Problems on Regular and Messy Behavior in Statis-tical Mechanics and Smooth Dynamics for Which I Would Like the Advice of Yasha Sinai David Ruelle What, in My Opinion, David Ruelle Should Do in the Coming Years Journal Article

In: Journal of Statistical Physics, vol. 108, no. 3/4, 2002.

Tags: Quantum Chaos

Lu, WT; Sridhar, S; others,

Spectra and wave functions of open chaotic billiards Inproceedings

In: APS Division of Atomic, Molecular and Optical Physics Meeting Abstracts, 2002.

Abstract | Tags: Quantum Chaos

Sridhar, Srinivas

Quantum Chaos in Microwave Billiards Inproceedings

In: APS Division of Atomic, Molecular and Optical Physics Meeting Abstracts, 2002.

Abstract | Tags: Quantum Chaos

Lu, Wentao T; Prance, Kristi; Pradhan, Prabhakar; Sridhar, S

Quantum correlations and classical resonances in an open chaotic system Journal Article

In: Physica Scripta, vol. 2001, no. T90, pp. 238, 2001.

Abstract | Tags: Quantum Chaos

Sridhar, S

Quantum resonances and decay of a fractal repeller observed using microwaves Inproceedings

In: APS Meeting Abstracts, 2000.

Abstract | Tags: Quantum Chaos

Sridhar, S

Quantum chaos, localization and tunnelling: microwave experiments on model geometries Journal Article

In: Philosophical Magazine B, vol. 80, no. 12, pp. 2129–2141, 2000.

Abstract | Tags: Quantum Chaos

Pance, Kristi; Lu, Wentao; Sridhar, S

Quantum fingerprints of classical ruelle-pollicott resonances Journal Article

In: Physical review letters, vol. 85, no. 13, pp. 2737, 2000.

Abstract | Tags: Quantum Chaos

Pradhan, Prabhakar; Sridhar, S

Correlations due to localization in quantum eigenfunctions of disordered microwave cavities Journal Article

In: Physical review letters, vol. 85, no. 11, pp. 2360, 2000.

Abstract | Tags: Quantum Chaos

Pradhan, Prabhakar; Pance, Kristi; Rose, Michael; Sridhar, S

From Localization to Chaos in experimental eigenfunctions of disordered microwave cavities Inproceedings

In: APS Meeting Abstracts, 2000.

Abstract | Tags: Quantum Chaos

Lu, Wentao; Viola, Lorenza; Pance, Kristi; Rose, Michael; Sridhar, S

Microwave study of quantum n-disk scattering Journal Article

In: Physical Review E, vol. 61, no. 4, pp. 3652, 2000.

Abstract | Tags: Quantum Chaos

Pance, Kristi; Viola, Lorenza; Sridhar, S

Tunneling proximity resonances: interplay between symmetry and dissipation Journal Article

In: Physics Letters A, vol. 268, no. 4-6, pp. 399–405, 2000.

Abstract | Tags: Quantum Chaos

Lu, Wentao; Viola, Lorenza; Pance, Kristi; Rose, Michael; Sridhar, S

Erratum: Microwave study of quantum n-disk scattering [Phys. Rev. E 61, 3652 (2000)] Journal Article

In: Physical Review E, vol. 62, no. 3, pp. 4478, 2000.

Abstract | Tags: Quantum Chaos

Lu, Wentao; Rose, M; Pance, K; Sridhar, S

Quantum resonances and decay of a chaotic fractal repeller observed using microwaves Journal Article

In: Physical review letters, vol. 82, no. 26, pp. 5233, 1999.

Abstract | Tags: Quantum Chaos

Sridhar, S

Wave Chaos and Localization in Closed Billiards and Open Scattering Systems: Microwave Experiments Inproceedings

In: APS March Meeting Abstracts, 1998.

Abstract | Tags: Quantum Chaos

Kudrolli, A; Sridhar, S

Experiments on quantum chaos using microwave cavities: Results for the pseudo-integrable L-billiard Journal Article

In: Pramana, vol. 48, no. 2, pp. 459–467, 1997.

Abstract | Tags: Quantum Chaos

Jacobs, T; Willemsen, Balam A; Sridhar, S

Quantitative analysis of nonlinear microwave surface impedance from non-Lorentzian resonances of high Q resonators Journal Article

In: Review of scientific instruments, vol. 67, no. 10, pp. 3757–3758, 1996.

Tags: Quantum Chaos

Kudrolli, A; Sridhar, S

Comment on “Gaussian Orthogonal Ensemble Statistics in a Microwave Stadium Billiard with Chaotic Dynamics: Porter-Thomas Distribution and Algebraic Decay of Time Correlations” Journal Article

In: Physical review letters, vol. 76, no. 16, pp. 3036, 1996.

Abstract | Tags: Quantum Chaos

Kudrolli, A; Kidambi, V; Sridhar, S

Experimental studies of chaos and localization in quantum wave functions Journal Article

In: Physical review letters, vol. 75, no. 5, pp. 822, 1995.

Abstract | Tags: Quantum Chaos

Prigodin, VN; Taniguchi, Nobuhiko; Kudrolli, A; Kidambi, V; Sridhar, S

Spatial correlation in quantum chaotic systems with time-reversal symmetry: Theory and experiment Journal Article

In: Physical review letters, vol. 75, no. 12, pp. 2392, 1995.

Abstract | Tags: Quantum Chaos

Kudrolli, A; Sridhar, S

QUANTUM CHAOS EXPERIMENTS USING MICROWAVE CAVITIES Inproceedings

In: Proceedings Of The 2nd Experimental Chaos Conference, pp. 184, World Scientific 1995.

Abstract | Tags: Quantum Chaos

Sridhar, S

Cavities of Chaos Journal Article

In: SCIENCE NEWS-WASHINGTON-, vol. 147, pp. 264–264, 1995.

Tags: Quantum Chaos

Kudrolli, A; Sridhar, S; Pandey, Akhilesh; Ramaswamy, Ramakrishna

Signatures of chaos in quantum billiards: Microwave experiments Journal Article

In: Physical Review E, vol. 49, no. 1, pp. R11, 1994.

Abstract | Tags: Quantum Chaos

Sridhar, S

Quantum Dynamics of Chaotic Systems Journal Article

In: 1993.

Tags: Quantum Chaos

Sridhar, S; Hogenboom, D; Kudrolli, A

Exper-imental eigenvalue spectra of “rough” and multiplyconnected billiards,” Journal Article

In: Quantum Dynamics of Chaotic Systems, eds. Yuan, JM, Feng, DH & Zaslavsky, GM (Gordon and Breach, Amsterdam), pp. 297–304, 1993.

Abstract | Tags: Quantum Chaos

Sridhar, S; Heller, EJ

Physical and numerical experiments on the wave mechanics of classically chaotic systems Journal Article

In: Physical Review A, vol. 46, no. 4, pp. R1728, 1992.

Abstract | Tags: Quantum Chaos

Sridhar, S; Hogenboom, DO; Willemsen, Balam A

Microwave experiments on chaotic billiards Journal Article

In: Journal of statistical physics, vol. 68, no. 1-2, pp. 239–258, 1992.

Abstract | Tags: Quantum Chaos

Sridhar, S; Parimi, PV; Lu, WT; Vodo, P; Derov, John S; Hanscom, AFRL; Bedford, MA

Negative Refraction and Imaging in Photonic Crystals Journal Article

In: 0000.

Abstract | Tags: Quantum Chaos

Harika, K; Swetha, BV; Renuka, B; Rao, Lakshman D; Sridhar, S

Analysis of Different Multiplication Algorithms & FPGA Implementation Journal Article

In: IOSR Journal of VLSI and Signal Processing (IOSR-JVSP), vol. 4, no. 2, pp. 29–35, 0000.

Tags: Quantum Chaos