The general problem of effectively using interactive engagement in non-introductory physics courses remains open. We present a three-year study comparing different approaches to lecturing in an intermediate mechanics course at the Colorado School of
Mines. In the first year, the lectures were fairly traditional. In the second year the lectures were modified to include Socratic dialogs between the instructor and students. In the third year, the instructor used a personal response system and Peer Instruction-like pedagogy. All other course materials were nearly identical to an established traditional lecture course. We present results from a new instructor-constructed conceptual survey, exams, and course evaluations. We observe little change in student exam performance as lecture techniques varied, though students consistently stated clickers were the best part of the course from which they learned the most. Indeed, when using clickers in this course, students were considerably more likely to become engaged than students in CSM introductory courses using the same methods.
Formation of bright envelope solitons from wave packets with a repulsive nonlinearity was observed for the first time. The experiments used surface spin-wave packets in magnetic yttrium iron garnet (YIG) thin film strips. When the wave packets are na
rrow and have low power, they undergo self-broadening during the propagation. When the wave packets are relatively wide or their power is relatively high, they can experience self-narrowing or even evolve into bright solitons. The experimental results were reproduced by numerical simulations based on a modified nonlinear Schrodinger equation model.
Strongly correlated quantum fluids are phases of matter that are intrinsically quantum mechanical, and that do not have a simple description in terms of weakly interacting quasi-particles. Two systems that have recently attracted a great deal of inte
rest are the quark-gluon plasma, a plasma of strongly interacting quarks and gluons produced in relativistic heavy ion collisions, and ultracold atomic Fermi gases, very dilute clouds of atomic gases confined in optical or magnetic traps. These systems differ by more than 20 orders of magnitude in temperature, but they were shown to exhibit very similar hydrodynamic flow. In particular, both fluids exhibit a robustly low shear viscosity to entropy density ratio which is characteristic of quantum fluids described by holographic duality, a mapping from strongly correlated quantum field theories to weakly curved higher dimensional classical gravity. This review explores the connection between these fields, and it also serves as an introduction to the Focus Issue of New Journal of Physics on Strongly Correlated Quantum Fluids: from Ultracold Quantum Gases to QCD Plasmas. The presentation is made accessible to the general physics reader and includes discussions of the latest research developments in all three areas.
Chaotic spin-wave solitons in magnetic film active feedback rings were observed for the first time. At some ring gain level, one observes the self-generation of a single spin-wave soliton pulse in the ring. When the pulse circulates in the ring, its
amplitude varies chaotically with time. Numerical simulations based on a gain-loss nonlinear Schrodinger equation reproduce the observed responses.
We reply to Jacek Dziarmaga, Piotr Deuar, and Krzysztof Sachas comment, arXiv:1001.1045, supporting the authors simulations but differentiating between near-mean-field and strongly quantum regimes. We clarify that we have three lines of evidence on d
ecay of dark solitons and connect our work to Liebs Type-II excitations and the true meaning of a quantum dark soliton.
This letter reports experimental results on a new type of soliton: the random temporal dark soliton. One excites an incoherent large-amplitude propagating spin-wave packet in a ferromagnetic film strip with a repulsive, instantaneous nonlinearity. On
e then observes the random formation of dark solitons from this wave packet. The solitons appear randomly in time and in position relative to the entire wave packet. They can be gray or black. For wide and/or very strong spin-wave packets, one also observes multiple dark solitons. In spite of the randomness of the initial wave packets and the random formation processes, the solitons show signatures that are found for conventional coherent dark solitons.
This article presents an overview of experimental efforts in recent years related to multidimensional solitons in Bose-Einstein condensates. We discuss the techniques used to generate and observe multidimensional nonlinear waves in Bose-Einstein cond
ensates with repulsive interactions. We further summarize observations of planar soliton fronts undergoing the snake instability, the formation of vortex rings, and the emergence of hybrid structures.
