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Faculty Profile Last Modified Time: 12:01:51 PM Mon, 6 Apr 2020   Contact Information F. Barry Dunning Associated Profiles  Sam and Helen Worden Professor of Physics, Rice University   Brockman Hall, Room No.: 320    bdunning@rice.edu     713-348-3544    Web Link    Experimental Atomic, Molecular, and Optical Physics, Nonlinear Dynamics, Chemical Physics    Associated Profiles Research and Expertise Appointments  Research and Expertise Research Interests   My research focuses on atoms in which one electron is excited to a state of very large principal quantum number n, termed Rydberg atoms. Such atoms possess properties quite unlike those normally associated with atoms in ground or low-lying excited states. For example, because the size of an atom scales as n2, they are physically very large. An atom with n~400 has a diameter approaching 20 ¼-m. Their classical electron orbital periods are also very long, ~10 ns at n~400, and this we exploit to control and manipulate their electronic wave functions using pulsed electric fields whose characteristic times (duration, rise/fall times) are less than this period. Application of such pulses leads to the formation of wave packets that comprise a coherent superposition of adjacent Rydberg states. These wave packets display novel dynamical behavior that can mimic the classical motion of an excited electron, thereby providing a bridge between quantum and classical physics. Our studies show that, with careful choice of the amplitude and width of the pulses (or application of several pulses), it is possible to control and manipulate atomic wavefunctions with remarkable precision. The goal is to use carefully-tailored sequences of pulses to engineer atomic wavefunctions and produce "designer" atoms to study classical-quantum correspondence, to use periodic trains of pulses to create non-dispersive wave packets and to probe non-linear dynamics and classical/quantum chaos, to study atom/field interactions in the ultra-fast ultra-intense regime, to explore information storage/retrieval in atoms, and to study the behavior of strongly-coupled Rydberg/Rydberg systems. Initial work centered on potassium Rydberg atoms contained in a tightly-collimated atomic beam but has now been extended to include strontium Rydberg atoms contained in both an atomic beam and in an ultra-cold atomic gas or Bose-Einstein condensate (BEC). The starting point for many of our studies is the production of strongly-polarized quasi-one-dimensional (quasi-1D) high-n Rydberg atoms by photo-exciting extreme red-shifted Stark states in the presence of a weak dc field. Protocols have been developed using pulsed electric fields to characterize such states and monitor their time evolution. Techniques have also been devised to convert such states into quasi-two-dimensional (quasi-2D) "circular" states in which the electron orbits in a plane, and probe their evolution. The opportunities afforded by the creation of quasi-1D and -2D atoms are being explored. These include the use of periodic drive fields to create localized non-dispersive wave packets that mimic the behavior of a classical electron and to transport these wave packets to states of higher n. Measurements with strontium Rydberg atoms show that, even at high n, the regime where dipole blockade becomes important can be accessed opening up new opportunities to study strongly-coupled Rydberg atom pairs and their possible manipulation to form long-lived "molecular" species through periodic driving. The production of long-lived "planetary atom" states in strontium that contain two excited electrons is also being examined. The evolution of cold Rydberg gases into a strongly-coupled ultracold neutral plasma through collisions is also under investigation. Studies of the control of the interactions between atoms in a strontium BEC by dressing the ground-state atoms with an admixture of a higher-lying Rydberg state using lasers have been initiated with the long-range goal of realizing soliton formation in three dimensions and creation of a supersolid. Because the Rydberg electron is typically far from its associated core ion it will, in collisions with neutral targets, behave as an independent particle allowing a Rydberg atom to be viewed as an ultra-low-energy electron trap. Potassium Rydberg atoms are therefore being used to examine electron attachment to molecules. The creation of novel negative ion species in such collisions is observed including the formation of negative ions in which the electron is weakly bound by the electric dipole moment of the parent molecule. The creation of heavy-Rydberg ion-pair states comprising a positive-negative ion pair that orbit at large radius weakly bound by their mutual electrostatic attraction is also seen. The physical and chemical properties of such species are being examined using a newly-commissioned apparatus.  Publications/Creative Works Click here to search for this faculty member's publications on PubMed.  Appointments Title Department / School Institution Sam and Helen Worden Professor Physics Rice University

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