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Ken Segall

Associate Professor of Physics

Physics & Astronomy , 317 Ho Science Center

p 315 2286597

I spent my grade school years in upstate New York and attended high school in Mahwah, N.J. In 1989 I attended Fairfield University in Connecticut, majoring in physics with a minor in mathematics, computer science, and philosophy.

In 1993 I moved up I-95 to New Haven, Conn., and attended graduate school in applied physics at Yale University. I received a PhD in 1999 in the group of Daniel Prober and was awarded Yale’s Harding-Bliss Prize in Engineering. I stayed on at Yale for eight months and worked as a post-doc in the research group of Rob Schoelkopf. In September of 2000, I moved to the Massachusetts Institute of Technology and did post-doctoral work in the group of Terry Orlando. In August of 2003 I started here at Colgate, and was promoted to associate professor with tenure in December of 2008.

I married Karen Cheal in 2002 in Cambridge, Mass., and we have two children, Nadia and Nico.

An important aspect of physics today is the effort to understand how the fundamental laws of nature result in complex behavior, often referred to as the study of emergent phenomena. For example, how does something as straightforward as a system of gas molecules organize itself into something as complex as a tornado? Two factors play a key role in the study of emergent phenomena: complexity, the number of constituents in a system, and nonlinearity, a property common to most system dynamics. Nonlinear systems which can be controlled, easily measured and scaled to large numbers are thus important to understand.

Networks of superconducting Josephson junctions are examples of such systems. Josephson junctions are inherently nonlinear systems which can be fabricated with adjustable parameters, measured in a straightforward fashion, and easily scaled to large network sizes. In addition, a large circuit of Josephson junctions measured over a long time contains dynamics which would be essentially impossible to calculate on a computer, but which can be observed with basic electrical measurements.

In our research, we study the behavior of networks of Josephson junctions. We have followed previous work in this field in studying soliton-like modes called fluxons or vortices and localized modes called discrete breathers. We have also begun work on synchronization in a system of disordered oscillators. Finally, we have devised a circuit of Josephson junctions to accurately model the time-dependent behavior of the voltage of a neuron, with an eye toward studying the emergent behavior of a large, coupled neural network. Our work fits in with Colgate University’s strong tradition of undergraduate student involvement in academic research.

Degree

BS, Fairfield University, 1993; PhD, Yale University, 1999

Teaching Experience

• Thermodynamics and Statistical Mechanics (Physics 372)
•Real-time Nonlinear Dynamics + Chaos (Physics/Math 407)
• Intro to Differential Equations (Physics 202)
• Sports and the Scientific Method (CORE 100, FSEM 133)
• General Physics III (Physics 122)
• Div/Grad/Curl (Physics 204)
• Electronics and Instrumentation (Physics 282)
• Solid State Physics (Physics 420)
• General Physics II (Physics 121)
• General Physics I (Physics 120)
• Mechanics (Physics 302)
• Advanced Topics and Experiments (Physics 410)

Specialities

Electronics, solid state physics, nonlinear dynamics, superconductivity, mechanics

Interests

Superconducting electronics, low temperature electron transport and superconductivity, nonlinear dynamics, quantum computing and quantum information, single photon detectors, analog simulation of neurons

Publications

“Josephson junction simulation of neurons,” P. Crotty, D. Schult and K. Segall, Physical Review E 82, 011914 (2010).

“Experimental Observation of Fluxon Diffusion in Josephson Rings,” K. Segall, A. Dioguardi, N. Fernandes and J.J. Mazo, Journal of Low Temperature Physics 154, 41-54 (2009).

“Thermal depinning of Josephson Fluxons in superconducting rings,” J.J. Mazo, F. Naranjo and K. Segall, Physical Review B78, 174510 (2008).

“Subgap biasing of Superconducting Tunnel Junctions without a Magnetic Field,” K. Segall, J. Moyer and J.J. Mazo, Journal of Applied Physics 104, 043920 (2008).

“Multiple-junction biasing of superconducting tunnel junction detectors,” K. Segall, J.J. Mazo and T.P. Orlando, Applied Physics Letters 86, 153507 (2005).

“Numerical Simulation of Multi-Junction Bias Circuits for Superconducting Detectors,” K. Segall, J.J. Mazo and T.P. Orlando, IEEE Transactions on Applied Superconductivity 15, 583-586 (2005).

“Dynamics and energy distribution of nonequilibrium quasiparticles in superconducting tunnel junctions,” K. Segall, C.M. Wilson, L. Li, L. Frunzio, S. Friedrich, M.C. Gaidis, and D.E. Prober, Physical Review B70, 214520 (2004).

“DC measurements of macroscopic quantum levels in a superconducting qubit structure with a time-ordered meter,” D.S. Crankshaw, K. Segall, D. Nakada, T.P. Orlando, L.S. Levitov, S. Lloyd, S.O. Valenzuela, N. Markovic, M. Tinkham, and K.K. Berggren, Physical Review B69, 144518 (2004).

“Impact of time-ordered measurements of the two states in a niobium superconducting qubit structure,” K. Segall, D.S. Crankshaw, D. Nakada, T.P. Orlando, L.S. Levitov, S. Lloyd, N. Markovic, S.O. Valenzuela, M. Tinkham, and K.K. Berggren, Physical Review B67 (Rapid communications), 220506 (2003).

“Experimental characterization of the two current states in a Nb persistent-current qubit,” K. Segall, D.S. Crankshaw, D. Nakada, B. Singh, J. Lee, T.P. Orlando, N. Markovic, S.O. Valenzuela and M. Tinkham, IEEE Transactions on Applied Superconductivity 13, 1009-1012 (2003).

“A high performance cryogenic amplifier based on a radio-frequency single electron transmitter,” K. Segall, K.W. Lehnert, T.R. Stevenson, R.J. Schoelkopf, P. Wahlgren, A. Aassime and P. Delsing, Applied Physics Letters 81, 4859 (2002).

“Fluxon ratchet potentials in superconducting circuits,” F. Falo, P.J. Martinez, J. Mazo, T.P. Orlando, K. Segall and E. Trias, Applied Physics A75, 263 (2002).

"Quantum partition noise in a superconducting tunnel junction" in Physical Review B64 (Rapid Communications), 180508 (2001)

"Noise mechanisms superconducting tunnel-junction detectors" in Applied Physics Letters 76, 2998 (2000)

"Single photon imaging x-ray spectrometers" in IEEE Transactions on Applied Superconductivity 9, 3326 (1999)

"Experimental quasiparticle dynamics in a superconducting, imaging x-ray spectrometer" in Applied Physics Letters 71, 3901 (1997)

"Spatial uniformity of single photon 1-D imaging detectors using superconducting tunnel junctions" in AIP Conference Proceedings 2002

"Single photon imaging spectrometers using superconducting tunnel junctions" EUCAS Proceedings 2, 615 (2000)

"RF single electron transistor readout amplifiers for superconducting astronomical detectors of x-ray to sub-mm wavelengths" in IEEE Transactions on Applied Superconductivity 11, 692 (2001)

"X-ray single photon 1-D imaging spectrometers" in IEEE Transactions on Applied Superconductivity 11, 685 (2001)

"A new noise source in superconducting tunnel junction photon detectors" in IEEE Transactions on Applied Superconductivity 11, 645 (2001)

"Optical/UV single-photon imaging spectrometers using superconducting tunnel junctions" in Nuclear Instruments & Methods A 444, 449 (2000)

“Single-photon 2-D imaging X-ray spectrometer employing trapping with four tunnel junctions,” L. Li, L. Frunzio, K. Segall, C.M. Wilson, D.E. Prober, A.E. Szymkowiak, S.H. Moseley, Nuclear Instruments & Methods A 444, 228 (2000).

“Single-photon imaging x-ray spectrometers using low noise current preamplifiers with dc voltage bias,” S. Friedrich, K. Segall, M.C. Gaidis, C.M. Wilson, D.E. Prober, P.J. Kindlmann, A.E. Szymkowiak, S.H. Moseley, IEEE Transactions on Applied Superconductivity 7, 3383 (1997).

“A superconducting x-ray spectrometer with a tantalum absorber and lateral trapping,” M.C. Gaidis, S. Friedrich, K. Segall, D.E. Prober, A.E. Szymkowiak, S.H. Moseley, IEEE Transactions on Applied Superconductivity 6, 1 (1996).

“Superconducting Nb-Ta-Al-AlOx-Al x-ray detectors with spatial resolution,” S. Friedrich, K. Segall, M.C. Gaidis, D.S. Toledano, D.E. Prober, A.E. Szymkowiak, S.H. Moseley, Nuclear Instruments & Methods A 370, 44 (1996).

“Cerenkov fiber sampling calorimeters,” K. Arrington, D. Kefford, J. Kennedy, R. Pisani, C. Sanzeni, K. Segall, D. Wall, D.R. Winn, R. Carey, S. Dye, J. Miller, L. Sulak, W. Worstell, Y. Efremenko, Y. Kamyshkov, A. Savin, K. Shmakov, E. Tarkovsky, 1993 IEEE Conference Record Nuclear Science Symposium and Medical Imaging Conference, Cat. No. 93CH3374-6 1, 119 (1993).

“Electron bombarded semiconductor gain in CVD diamond,” B.Y. Lin, C.P. Beetz, D.R. Winn, K. Segall, International Electron Devices Meeting 1992 Technical Digest, Cat. No. 92CH3211-0, 747 (1992).

“Copper-scintillating fiber hadron calorimeter tower prototypes,” D. Brown, R. Carey, S. Dye, E. Hazen, D. Higby, J. Miller, L. Sulak, J. Sullivan, W. Worstell, W. Brower, H. Paar, D. Kefford, R. Pisani, K. Segall, D. Wall, D.R. Winn, N. Akchurin, J. Langland, Y. Onel, J. Sandro, C. Bromberg, R. Miller, B. Moore, J. Reidy, W. Bugg, R. Kroeger, R. Wigmans, F. Ayer, C. Elder, H. Cohn, Y. Kamyshkov, F. Placil, M. Rennich, A. Savin, K. Shmakov, A. Smirnov, K. Young, Conference Record of the 1992 IEEE Nuclear Science Symposium and Medical Imaging Conference, Cat. No. 92CH3232-6 1, 274 (1992).

“Scintillating fiber calorimeters with cast absorbers,” D. Brown, R. Carey, S. Dye, E. Hazen, D. Higby, J. Miller, B.L. Roberts, L. Sulak, C. Wang, W. Worstell, C. Lane, D. Boccuzzi, D. Scrofani, K. Segall, D. Wall, D.R. Winn, C. Bromberg, J. Huston, R. Miller, C. Yosef, A. David, N. Diaczenko, S. Zaman, A. Sanzgiri, R. Webb, D. Acosta, J. Branson, B. Ong, H. Paar, M. Sivertz, D. Thomas, F. Ayer, C. Elder, D. Sullivan, Conference Record of the 1991 IEEE Nuclear Science Symposium and Medical Imaging Conference, Cat. No. 91CH3100-5 1, 274 (1991).

“Diamond film optical x-ray and particle detectors,” C.P. Beetz, B. Lincoln, D.R. Winn, K. Segall, M. Vasas, D. Wall, IEEE Transactions on Nuclear Science 38, 107 (1991).

“Diamond film optical semiconductors,” K. Segall, Proceedings NCUR VI (1991), Vol. II, by Univ. of North Carolina at Asheville, Robert D. Yearout ed. (1992).

Professional Experience

• Postdoctoral associate, M.I.T., September 2000 to July 2003
• Postdoctoral associate, Yale University, January to September 2000

Distinctions

• Yale Engineering Harding-Bliss Award, May 2000
• NASA Graduate Student Research Program (GSRP) Fellowship, 1994-1997
• Department Award for Excellence in Physics, Fairfield University, May 1993
• Presidential Scholar (Full Tuition Scholarship), Fairfield University 1989-1993
• Salutatorian, Mahwah High School 1985-1989