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Prof. Michael Shay elected a Fellow of the American Physical Society

A hearty congratulations is extended to Professor Michael Shay who has just been elected a Fellow of the American Physical Society. The citation, which will appear on his Fellowship Certificate, will read: “For pioneering contributions to understanding magnetic reconnection, including the nature of collisionless reconnection, and of plasma turbulence.” This is a great achievement - it is limited to no more than one half of one percent of the membership.

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Dr. Wang received his Ph.D. in 2008 for the studies of magnetic tunnel junctions (MTJs) under the supervision of Prof. Xiao within the Center for Spintronics and Biodetection. During his subsequent postdoctoral research at the Johns Hopkins University, he published several high profile articles, including one in Nature Materials on spin-transfer torque in MTJs assisted by electric field to reach the limit of ultralow energy consumption. Dr.

Date
Time
2:00PM
Location
215 Sharp Lab
Speaker
Georg Raithel, Dept of Physics, Universitiy of Michigan
Host
Lyman

The minimal-coupling Hamiltonian describing the interaction between an atom and a light field includes an A·p term, which is employed in spectroscopy, and an A·A term, which is relevant in light scattering. Here it is shown that the A·A term can be employed in high-precision atomic spectroscopy by providing a strong spatial variation of the field intensity within the volume of the atom, and by modulating the field intensity in time at the atomic transition frequency of interest. These requirements are satisfied for Rydberg atoms trapped in an intensity-modulated optical lattice [1]. Selection rules in this type of spectroscopy are greatly relaxed in comparison with the standard selection rules, allowing access to previously forbidden transitions [2, 3]. We have demonstrated the new spectroscopy by scanning the light modulation frequency over a Rydberg-atom resonance and probing the population in the target Rydberg state [3]. More recently, we have driven transitions at higher harmonics of the drive; this provides convenient access to sub-Terahertz transitions between Rydberg levels. Further, we have shown that optical-lattice Rydberg atom traps support “magic” transitions [4].
In a second experiment with Rydberg atoms in an optical lattice, we employ doubly-resonant two-photon excitation into the 74S Rydberg state to spectroscopically measure the dynamic scalar and tensor polarizabilities of the rubidium 5P3/2 level [5]. To reach the necessary high intensities, we employ a cavity-generated 1064-nm optical-lattice light field, allowing us to obtain intensities near 2x1011 W/m2. In the evaluation of the data we use a self-referencing method that renders the polarizability measurement largely free from the intensity calibration of the laser light field. We obtain experimental values of -1149 +/- 2.5% and 563 +/- 4.2% for the scalar and tensor parts, in atomic units.
[1] S. E. Anderson, K. C. Younge, G. Raithel, Phys. Rev. Lett. 107, 263001 (2011).
[2] B. Knuffman and G. Raithel, Phys. Rev. A 75, 053401 (2007).
[3] K. R. Moore, S. E. Anderson, G. Raithel, Nature Communications 6 (2015).
[4] K. Moore, G. Raithel, “Nonlinear and magic ponderomotive spectroscopy,” arXiv:1506.01761 (2015).
[5] Y.-J. Chen, L. F. Gonçalves, G. Raithel, “Measurement of Rb 5P3/2 scalar and tensor polarizabilities in a 1064 nm light field,” arXiv:1507.05675 (2015).

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Prof. Xin Fan received his Ph.D. in 2010 under the supervision of Prof. John Q. Xiao for experimental research on magnetic dynamics in various nanostructures. He continued as postdoc in the same group where he studied emerging topic of  spin-orbit torque in ultrathin magnetic bilayers.  In the Fall of 2014, he became Assistant Professor of Physics at the University of Denver.

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Dr. Souleymane Omar Diallo (Souley) graduated in 2007 with thesis in the field of Neutron Scattering appplications in Condensed Matter Physics supervised by Prof. Glyde. He is currently Instrument Scientist at BASIS (BL-2) Quantum Condensed Matter Division at Oak Ridge National Laboratory.

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Dr. Shu received his Ph.D. in 2014 for the studies of low temperature surface passivation of crystalline silicon and its application to interdigitated back contact silicon heterojunction (IBC-SHJ) solar cell under the supervision of Prof. BIrkmire. Dr. Shu is now a staff engineer at Western Digital, CA.

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Dr. Shabbar Raza Rizvi obtained his Ph.D. degree in 2013 in theoretical particle physics under the supervision of Prof. Qaisar Shafi. The topic of his Ph.D. thesis was Low Energy Predictions from Supersymmetric Grand Unified Theories. He is currently a post doctoral fellow at Kavli Institute of Theoretical Physics China, Chinese Academy of Sciences, Beijing.

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