BA cum laude Univ North Carlina, Phi Beta Kappa, MS/MS/Ph.D. University of Michigan, Senior Staff Physics Hughest AIrcraft Research Laboratories, Professor University of Michigan. Guggenheim Fellow, Rackham Doctoral Mentor Award, 2010recipient of the American Physical Society Isakson Prize, Topical editor of J. American Optical Society, Assoc. Editor Encyclopedia of Modern Optics. Over 200 papers published in peer reviewed journals.
Quantum Opto-Electronics: Research in our group focuses on the use of coherent optical interactions to study, control, and manipulate the quantum properties of semiconductor heterostructures. Recent research has provided for the coherent spectroscopy study of single quantum dots showing that these structures behave like artificial atoms. The strong three dimensional confinement leads to reduced interactions with the surrounding environment and hence reduced decoherence of the quantum phase of the system. Using these results we have demonstrated our ability to optically prepare the wave function of the system. Measurements, based on using phase locked short optical pulses to produce quantum interferograms of the luminescence, show our ability to modulate the population and orientation on a time scale short compared to the coherence time of the electronic excitation. Our work is moving toward examining these structures as quantum devices for application to quantum computing.
Biomolecular Laser Spectroscopy: The research program, run jointly with Professor Ari Gafni (Biological Chemistry) focuses on the development and application of advanced laser spectroscopy methodology and other biophysical techniques for the study of protein folding and dynamics. Emphasis is on understanding the nature of structural changes that occur in protein folding related diseases such as Alzheimer's, mad cow, etc. These diseases occur following post synthetic modification of protein conformation for reasons that are not understood. Our work has shown that structural changes deep in the core of a protein continue even after folding has lead to full biological activity, and that these changes are reflected in both the physical as well as the chemical behavior of the protein.
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).
Shi, J., Gafni, A. and Steel, DG: Application of single molecule spectroscopy in studies of enzyme kinetics and mechanisms. Meth. Enzymol. 450, pp 129-157 (2008).
Jun Cheng, Xiaodong Xu, D. G. Steel, A. S. Bracker, D. Gammon, Wang Yao, and L. J. Sham, “Stimulated Raman spin-coherence and spin-flip induced hole burning in charged GaAs quantum dots,” Phys. Rev. B 77, 115315 (2008).
Jeffrey R. Brender, Edgar L. Lee, Marchello A. Cavitt1, Ari Gafni, Duncan G. Steel, Ayyalusamy Ramamoorthy “Amyloid Fiber Formation and Membrane Disruption are Separate Processes Localized in Two Distinct Regions of IAPP, the Type-2-Diabetes-Related Peptide”, Journal of the American Chemical Society 130 pp 6424-6429 (2008).
Xiaodong Xu, Bo Sun, Erik D. Kim, Katherine Smirl, P. R. Berman, D. G. Steel, A. S. Bracker, D. Gammon, and L. J. Sham, “A Single Charged Quantum Dot in a Strong Optical Field: Absorption, Gain, and the AC Stark, Effect” Phys. Rev. Lett. 101, 227401 (2008).
Xiaodong Xu, Bo Sun, Paul R. Berman, Duncan G. Steel, Allan S. Bracker, Dan Gammon, L. J. Sham, “Coherent Population Trapping of an Electron Spin in a Single Negatively Charged Quantum Dot,” Nature Physics 4, pp692 - 695 (2008).
Xiaodong Xu, Wang Yao, Bo Sun,1 Duncan G. Steel, Allan S. Bracker, Dan Gammon, L. J. Sham Optically Controlled Locking of the Nuclear Field via Coherent Dark State Spectroscopy , Nature 459, pp1105-1109 (2009).
Xiaodong Xu, Bo Sun, P. R. Berman, Dan Gammon, L. J. Sham, Duncan G. Steel, “Strong Optical Field Study of a Single Self-Assembled Quantum Dot,” invited Solid State Communications 149, pp1479-1484 (2009)
Pamela T. Wong, Joseph A. Schauerte, Kathleen C. Wisser, Hao Ding, Edgar L. Lee, Duncan G. Steel, Ari Gafni “Amyloid-β membrane binding and permeabilization are distinct processes influenced by membrane charge and fluidity,” J. Mol. Biol. 386, 81-96 (2009).
Hao Ding, Pamela T. Wong, Edgar L. Lee, Ari Gafni, and Duncan G. Steel, “Determination of the Oligomer Size of Amyloidogenic Protein beta-Amyloid(1-40) by Single-Molecule Spectroscopy ” , Biophysical Journal 97, pp912-921(2009).
J. Schauerte, Pam Wong, Kathleen Wisser, Duncan Steel, Ari Gafni, “Simultaneous Single-Molecule Fluorescence and Conductivity Studies Reveal Distinct Classes of A beta Species on Lipid Bilayers,” Biochemistry 49, 3031-3039 (2010).
Erik D. Kim, Katherine Smirl, Xiaodong Xu, Bo Sun, D.G. Steel, A. S. Bracker, D. Gammon, and L. J. Sham, “Fast spin rotations and optically controlled geometric phases in a quantum dot,” Phys. Rev. Lett. 104, 167401 (2010). DOI: 10.1103/PhysRevLett.104.167401
Erik D. Kim, Katherine Truex, Yanwen Wu, A. Amo, Xiaodong Xu, and D. G. Steel, A. S. Bracker and D. Gammon, and L. J. Sham, “Picosecond Optical Spectroscopy of a Single Negatively Charged Self-Assembled InAs Quantum Dot,”, Applied Physics Letters 97, p. 113110 (2010). DOI: 10.1063/1.3487783
E.D. Kim, K. Truex, X.D. Xu, Bo Sun, D.G. Steel, Allan Bracker, Dan Gammon, L.J. Sham, “Fast optically driven spin qubit gates in an InAs quantum dot. Conference on Advances in Photonics of Quantum Computing, Memory, and Communication III, JAN 27-28, 2010 San Francisco, CA, Book Series: Proceedings of SPIE-The International Society for Optical Engineering 7611 (2010). DOI: 10.1117/12.842072
Jing Wang, Ren-Bao Liu, Bang-Fen Zhu, L. J. Sham, and D. G. Steel, ”Coherent spin control by electromagnetic vacuum fluctuations” Phys. Rev. A 83, 053833 (2011) DOI: 10.1103/PhysRevA.83.053833
Qiong Huang and Duncan S. Steel, “Optical excitation effects on spin-noise spectroscopy in semiconductors,” Phys. Rev. B 83, 155204 (2011). DOE:10.1103/PhysRevB.83.155204.
Bo Sun, Wang Yao, Xiaodong Xu, Allan S. Bracker, Daniel Gammon, L. J. Sham, Duncan Steel , “Persistent Optical Nuclear Spin Narrowing in a Singly Charged InAs Quantum Dot,” invited, JOSAB 29 2, pp A119-A126 (2012).
Bo Sun, Colin Ming Earn Chow, and Duncan G. Steel, Allan S. Bracker and Daniel Gammon, L.J. Sham, “Persistent narrowing of nuclear-spin fluctuations in InAs quantum dots using laser excitation,” Physical Review Letter, 108 18, p187401 (2012) DOI: 10.1103/PhysRevLett.108.187401.
Robin D. Johnson, Joseph A. Schauerte, Kathleen C. Wisser, Ari Gafni, and Duncan G. Steel, “Determination of Amyloid-β40 Oligomer Size on Live Cells By Single Molecule Microscopy,” PLoSOne 6(8), e23970 (2011). PMID: 21901146, PMCID: PMC3162019.
Robin D. Johnson, Joseph A. Schauerte, Chun-Chieh Chang, Kathleen C. Wisser, J. Christian Althaus, Cynthia J. L. Carruthers, Michael A. Sutton, Duncan G. Steel, and Ari Gafni, “Single-molecule imaging reveals Aβ42:Aβ40 ratio-dependent oligomer growth on neuronal processes”, Biophysical Journal 104 pp894-903 (2013). PMID: 23442968. http://dx.doi.org/10.1016/j.bpj.2012.12.051.
Hao Ding, Joseph A. Schauerte, Duncan G. Steel, and Ari Gafni, “β-amyloid(1-40) Peptide Interactions with Supported Phospholipid Membranes: A Single Molecule Study” Biophysical Journal 103 pp1500-1509 (2012). PMID: 23062342 http://dx.doi.org/10.1016/j.bpj.2012.08.051
J. R. Schaibley, A. P. Burgers, G. A. McCracken, and D. G. Steel_ A. S. Bracker and D. Gammon L. J. Sham, “Direct Detection of Time Resolved Rabi Oscillations in a Single Quantum Dot via Resonance Fluorescence”, in press PRB (2012).
J. R. Schaibley, A. P. Burgers, G. A. McCracken, L-M Duan, P. R. Berman, and D. G. Steel, A. S. Bracker and D. Gammon L. J. Sham, “Demonstration of quantum entanglement between a single quantum dot electron spin and a photon”, in press PRL (2012).