People

Professor Reis’s research interests are in ultrafast processes in condensed matter (as well as atomic and molecular) systems. When an intense femtosecond laser pulse is absorbed in a solid, it can create extreme nonequilibrium conditions that occur on the femtosecond to picosecond time-scale. Professor Reis’s group studies the coupling between electronic and vibrational degrees of freedom when near degenerate carrier densities are produced, and the role that each plays in ultrafast structural changes. These transient effects are best studied by time-resolved techniques such as x-ray diffraction, where we can in follow the motion of the atoms on a time-scale comparable to its vibrational period. Through its unique view of motion on the atomic scale, this research helps us to understand the interplay between structure and function, such as how energy is transported in bulk materials and across interfaces and how and why a solid melts.

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Professor Bucksbaum's research interest is in fundamental light-matter interactions, and especially in the control of quantum systems using ultrafast laser fields. He developa new sources of ultrafast laser light in the infrared, visible, ultraviolet, and x-ray regions of the light spectrum.
Professor Bucksbaum is a member of the National Academy of Sciences, a Fellow of the America Physical Society, and the Optical Society of America. He is Editor of VJUltrafast, the APS Virtual Journal of Ultrafast Science. He is also a recipient of the 2000 Margaret and Herman Sokol Faculty Award in the Sciences.

Project:
1. Quantum Computing using Rydberg Atoms

2. Above-Threshold Double-Ionization Spectroscopy of Argon

3. Terahertz Field Shaping

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Professor Chupp and his group pursue a program that uses precision measurement techniques and symmetry principles in particle physics investigations and applies the technology developed for those investigations to a variety of endeavors. The primary current efforts use polarized cold neutron beams and rare isotopes. The hadronic weak interaction is being studied in the n+p > d+gamma experiment currently at Los Alamos. Neutron beta-decay provides a probe of new physics that manifests time-reversal violation in the emiT experiment, which recently completed running at NIST. The new Fundamental neutron Physics Beamline at the SNS at Oak Ridge will provide a new generation of high precision experiments including n +p > d+gamma, PANDA, the Proton Asymmetry in Neutron Decay experiment, and abBA, a global set of neutron decay correlation measurements. Time revesal invariance violation is also manifest in the permanent electric dipole moments (EDMs) induced in atoms by elementary particle interactions beyond the Standard Model. Rare isotopes, e.g. 223-Rn, are used because large enhancements of time- reversal violating effects are expected due to octupole deformation of the nucleus. Experiment E-929 at TRIUMF will measure the EDM of 223-Rn. The Rare Isotope Accelerator, RIA, will produce much greater quantities of 223-Rn and provide for more precise measurements. We also continue to work on applications of laser polarized 129-Xe to medical imaging.

Project:
1. Applications of laser polarized xenon to biology and medicine
2. Radon-EDM experiment
3. Neutron decay and PANDA

References:
E. R. Tardiff, J. A. Behr, T. E. Chupp, K. Gulyuz, R. S. Lefferts, W. Lorenzon, S. R. Nuss-Warren, M. R. Pearson, N. Pietralla, G. Rainovski, J. F. Sell, G. D. Sprouse,Polarization and relaxation of radon

Merlin’s research specialty is experimental condensed matter physics. His areas of expertise include various optical techniques and, in particular, spontaneous and impulsive (stimulated) Raman spectroscopy. In the past several years, he has used light scattering to study a wide range of systems such as rare-earth magnetic semiconductors, mixed-valence compounds, transition-metal oxides, A15 superconductors, intercalated graphite and GaAs-AlAs superlattices. His current interests focus on the generation and control of coherent vibrational and electronic fields using ultrafast laser and x-ray pulses, and negative refraction. Merlin and collaborators pioneered experimental work on Fibonacci superlattices, the quantum-confined Pockels effect and squeezed phonons. Other significant contributions include the earliest light-scattering studies of interface phonons, folded acoustic modes and shallow impurities in GaAs/AlAs heterostructures, and the development of the technique of magneto-Raman scattering.

Merlin is a Fellow of the American Physical Society (1996), the Optical Society of America (2000), the von Humboldt Foundation (1987) and the John Simon Guggenheim Memorial Foundation (2007). Other honors include the 2006 Frank Isakson Prize of the American Physical Society for Optical Effects in Solids and Lannin Lecturer (2002) at the Department of Physics, Pennsylvania State University. Merlin is also a member of the Editorial Board of the Springer Series in Solid State Sciences and the journal Solid State Communications.

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Theodore B. Norris is a Professor in the Electrical Engineering and Computer Science Department at the University of Michigan. He is Director of the Center for Ultrafast Optical Science in the College of Engineering, and is Director of the Optics and Photonics Laboratory in the EECS Department. He received his B.A. in Physics (with Highest Honors) from Oberlin College in 1982, and his PhD in Physics from the University of Rochester in 1989, with a dissertation on time-resolved tunneling in semiconductor heterostructures.  He continued his investigations of time-resolved optical studies of semiconductors at Thomson-CSF in France 1989-1990.  During 1990-1992 he was an Assistant Research Scientist at the Ultrafast Science Laboratory; he joined the EECS faculty as an Assistant Professor in 1992.  His research interests include the application of femtosecond optical techniques to the physics of nanostructures, the development of new ultrafast optical and electronic probes with high spatial resolution for applications to semiconductor nanostructures and biological imaging, the application of ultrafast optics to biomedical imaging, in vivo sensing, and cancer therapeutics, the generation of THz radiation, and nanoacoustic imaging with picosecond coherent phonon pulses.  This work has appeared in over 130 journal and 180 conference publications.  His research is performed at the Center for Ultrafast Optical Science and the Electrical Engineering and Computer Science Department at the University of Michigan.  He is a Fellow of the Optical Society of America, Fellow of the American Physical Society, and a member of IEEE.    

Project:
1. Ultrafast Dynamics in semiconductors

2. THz optelectronics and coherent control

References:
G. Chang, C. J. Divin, C. -H. Liu, S. L. Williamson, A. Galvanauskas, and T. B. Norris, "Power scalable compact THz system based on an ultrafast Yb-doped fiber amplifier," Opt. Express 14, 7909-7913 (2006)

My research focuses on theory and implementation of quantum information science. Quantum information science investigates how to characterize the mysterious concept of "entanglement" arising from quantum mechanics, how to use it as a resource for applications in various information processing tasks, and how to achieve better understanding of quantum many-body systems based on this concept. One main task of quantum information science is to find physical implementations in which quantum entanglement can be created and manipulated at will for realization of super-fast quantum computation or for secure quantum communication and cryptography. Our group is pursuing innovative ideas and theoretical schemes to advance implementation of quantum information in various kinds of physical systems.

For physics of ultracold atoms, the primary interest of our group lies in study of strongly correlated many-body phenomena arising from this atomic system. Investigation of ultracold bosonic or fermionic atomic gas remains one of the most active fields of physics ever since the achievement of Bose-Einstein condensation in 1995. Recently, studies in this field evolve into a new phase when the interactions between the atoms can be manipulated at will to realize various kinds of strongly correlated many-body systems. Compared with condensed matter materials, this atomic system has the advantage that complicated strongly correlated physics can be studied under highly controllable environments thanks to its unparalleled controllability and diversity.

Project:
1. Quantum simulation of many-body physics with ultracold atoms

2. Implementation of quantum communication and computation

References list

Professor Berman is engaged in theoretical research related to the interaction of radiation with matter. Of particular interest is the identification of atom-field configurations which can result in qualitatively new phenomena. Among topics his research group is currently investigating are the nonlinear spectroscopy of laser cooled atoms; coherent transients of cold atoms; coherent transient studies of atomic recoil accompanying absorption or emissions of radiation; theories of laser cooling; atomic deflection in optical fields; entangled states; atom interferometry, and spin squeezing as applied to quantum information processing.

Professor Berman is a Fellow of the American Physical Society.

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References:
P. R. Berman, Change in propagation constant and propagation velocity in a dielectric: A microscopic approach. Phys. Rev. A 76, 042106 (2007)

Professor Steel researches quantum optics in condensed matter physics: the interaction of light with condensed matter is an extremely complex and rich field of physics. The interest in direct bandgap semiconductors for potential applications in quantum optoelectronics has shown that current understanding of these systems is very poor. The interaction of light with these materials is an intrinsic many-body problem, but the effects of disorder greatly complicate the description of these systems and create the opportunity for observing new optical phenomena such as super radiance, photon echoes, and Rabi flopping from excitons. Professor Steel's condensed matter group is now focusing on the study of quantum dots and nanostructures with experiments aimed at problems in quantum computing. These systems are particularly important as nanofabrication technology develops. Recent work has demonstrated optically induced and detected quantum entanglement in a single quantum dot. Efforts are now underway to demonstrate coherent optical control of spins and demonstration of a simple quantum algorithm.

Professor Steel's research in biophysics: focuses on developing and applying optical and laser based methodologies, especially single molecule spectroscopy, to the study of the second half of the genetic code. The first part of the genetic code relates to structure and information stored in DNA, specifically, the DNA codes for the amino acid sequence of proteins, the affecters of all biological function. However, proteins are complex three-dimensional structures whose structure and function are uniquely related to the linear amino acid sequence. The folding of the one dimensional structure into a 3 dimensional structure is a key step leading to biological funciton of the protien. However, sometimes, the protein misfolds leading to serious diseases. In our lab, we are now working on a class of misfodling diseases called amyloid diseases. These diseases are characterized by the deposits of specific kinds of aggregates in the target tissue and ultimately lead to cell death. Examples of these diseases include Alzheimer's, Type II diabetes, Parkinson's, and Huntington's. The lab is now using laser spectroscopy at the single molecule level to understand the origin of cellular toxicity. The cell appears to be caused by small oligomers of the incorrectly folded protein, but high heterogeneity, low concentrations and their metastable state make it a challenge to study this problem with conventional methods. Single molecule spectroscopy enables us to follow the toxic events as a function of time and characterize the toxic intermediate of the oligomeric species.

Professor Steel is a Guggenheim Scholar and a Fellow of the American Physical Society, Optical Society of America, and the IEEE.

Project:
1. Protein Folding Diseases

2. Quantum Computing, Spintronics, and Nano-Optics

References:
Xiaodong Xu, Bo Sun, Paul R. Berman, Duncan G. Steel, Allan Bracker, Dan Gammon, Lu
J. Sham, Coherent optical spectroscopy of a strongly driven quantum dot,  Science, 317 pp
929-932 (2007).

The majority of interesting reactions from a biological, environmental, or engineering perspective, occur in fluid condensed phase environments. In such an environment a chemical reaction is controlled by intermolecular interactions with surrounding solvent bath as well as by the intramolecular Hamiltonian. Interaction with the solvent often results in a situation where reactions are controlled by the competition between intermolecular and intramolecular energy relaxation on the time scales ranging from femtoseconds to picoseconds. The goals of our research program are three fold:

(1) To develop a detailed understanding of the fundamental processes which govern chemical reaction dynamics in fluid environments.

(2) To use sculpted light pulses to control reactions in condensed phases.

(3) To use short light pulses to establish synchronization and study enzyme mechanism in complicated biological systems.

Project:
1. Small Molecules

2. Biophysics

3. Coherent Control

References:
Carroll, E. C., Pearson, B. J., Florean, A. C., Bucksbaum, P. H., and Sension, R. J., 2006, "Spectral phase effects on nonlinear resonant photochemistry of 1,3-cyclohexadiene
in solution" The Journal of Chemical Physics, v124 (11) 114506

Advances in ultrafast optical technology have made possible the generation of single-cycle electromagnetic pulses whose bandwidths are comparable to the center frequency. Because different frequency components diffract differently, such pulses undergo significant temporal reshaping even when they propagate through free space. Because they contain only one cycle they cannot be properly described by the slowly varying envelope approximation. We have obtained exact solutions of Maxwell's equations that correctly describe the spatiotemporal evolution of focused single-cycle electromagnetic pulses. These solutions show how the Gouy phase shift leads to polarity reversals and temporal reshaping as the pulses propagate. The results have implications for both terahertz pulses and few-cycle femtosecond laser pulses. We are currently investigating the nonlinear interactions of these single-cycle pulses.

A second area of research involves novel grating structures in semiconductor lasers. We are investigating two-dimensional distributed feedback lasers and their potential for high power, single longitudinal and lateral mode operation. We are also studying Bragg amplifiers for wavelength conversion applications.

Project:
1.  Tunneling Time, Slow Light, and Fast Light

2.  Nonlinear Phenomena in Optical Fibers and Photonic Bandgap Structures

References:
1. Herbert G. Winful, “Tunneling time, the Hartman effect, and superluminality: a proposed resolution of an old paradox,” Phys. Rep. v436, 1 (2006).

2. Herbert G. Winful, “The nature of superluminal barrier tunneling,” Phys. Rev. Lett. 90, 023901 (2003).

3. Herbert G. Winful, “Delay time and the Hartman effect in quantum tunneling,” Phys. Rev. Lett. 91, 260401 (2003).