Neutral Atom Analogs to Basic Electric Circuit Elements
|Venue:||Academic Health Center 3-205|
Atomtronics, a relatively new field of physics, seeks to re-engineer electronics where atoms are the basic carriers of information. Today, electronics only exploits the charge of the electron; it is becoming more and more clear, however, that simply utilizing the spin of the electron would enable novel ways to store information. Devices based on so-called spintronics have the potential to revolutionize electronics. The atom, having a more complex internal structure than the electron, makes the possibilities with atomtronics far richer than those with spintronics. Crossed laser beams, producing optical lattices, and lasers with exotic spatial distributions, such as higher order Laguerre-Gauss modes, provide a means for establishing optical dipole potentials that have lead to several cold atom-based analogs to electronics and condensed states of matter. Persistent currents in a ring, a close atom analog to a superconducting circuit, and even a Josephson junction are just two examples of circuit analogs that have been demonstrated. While these harmonic potentials have received the most attention, arbitrary, non-harmonic potentials would allow a host of new analogs to be constructed, including more basic electrical elements. Exploiting an adaptation of a generalized phase-contrast approach, we have generated high-quality two-dimensional (2D) optical patterns that are ideal for creating low-noise potentials for neutral atoms – free-space atom chips. The chip is composed of an etched “light substrate” – a 2D sheet of light that is either red or blue detuned from the atomic resonance. The substrate is etched by the spatially-shaped beam propagating in a direction orthogonal to the plane of the sheet, which can be either red detuned or blue detuned as well. In contrast to the more familiar material-based atom chips, free-space atom chips can possess potentials that are non-harmonic, have sharp walls and barriers that can even be modified on a timescale commensurate with the flow of an atomic BEC. We have taken the initial steps toward realizing these chips by creating RLC circuits, the resistance and inductance of which are equivalent to the Sharvin (ballistic) resistance in metals and the usually small kinetic inductance, respectively. Similarly, the capacitance is related to the imbalance between the number of atoms and the chemical potential between two points in the circuit. To our knowledge, this is the first demonstration of an atomtronics circuit with analogs to basic elements of an electronic circuit and the first direct observation in real time of the flow of an ideal gas through a channel.
Wendell T. Hill, III holds the rank of Professor at the University of Maryland, College Park, with appointments in the Institute for Physical Science and Technology and the Department of Physics and is also a fellow of the Joint Quantum Institute (JQI). He earned his BA from the University of California, Irvine, in 1974 and his PhD from Stanford University in 1980, both in physics. He is a guest worker at National Institute for Standards & Technology (NIST), where he was a postdoc before joining the faculty of the University of Maryland in 1982, as well as a visiting scientist at Lawrence Livermore National Labs. He has held visiting positions with Instituto Venezalano de Investigaciones (Venezuela), Université de Paris-Sud, (Orsay, France) and JILA at the University of Colorado. Hill’s honors include Fellow of the American Physical Society (APS), Fellow of the National Society of Black Physicists, Presidential Young Investigator of the National Science Foundation (NSF) and has been profiled by the History Makers. Hill’s research interests are broad with publications ranging from high-energy particle physics to ultracold atoms; he has wrote the introductory chapter on electromagnetic radiation for the Encyclopedia of Applied Spectroscopy, published in 2009 by Wiley and is the co-author of the physics text Light-Matter Interaction: Atoms and Molecules in External Fields and Nonlinear Optics, published in 2007 by Wiley. His current investigations fall into three areas within atomic, molecular and optical (AMO) physics: (1) ultrafast dynamics and quantum control; (2) ultraintense laser-matter interaction and high-energy density physics; and (3) atomtronics and quantum information science. Hill has been a member of and chaired numerous program committees for national and international conferences, has served on several committees (some of which he also chaired) for the APS, the Optical Society of America (OSA), the National Academy of Sciences (NAS) and NSF, and has served as the program officer for the $20M AMO program at NSF (2010-2012 academic years). He has also been instrumental in production of reports for the NAS, APS and NSF promoting physics and community action for improved health of physics (AMO in particular) in the US as well as the engagement of more members of underrepresented groups in physics, all while teaching and pursuing research within the JQI at the University of Maryland.