Bulletin of the American Physical Society
2016 Annual Meeting of the Far West Section
Volume 61, Number 17
Friday–Saturday, October 28–29, 2016; Davis, California
Session S4: Education & General Physics |
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Chair: Peter Beiersdorfer, Lawrence Livermore National Laboratory Room: Ball Room C |
Saturday, October 29, 2016 2:00PM - 2:12PM |
S4.00001: Using the Cycloid to Motivate the E and B Transformations Marc Frodyma, My Phuong Le Einstein's route to special relativity was via electrodynamics, as evidenced by the title of his 1905 paper: ``The Electrodynamics of Moving Bodies''. Relativity emerges naturally from viewing simple electromagnetic systems in different frames of reference. Before obtaining the correct field transformation equations, Einstein applied the Galilean transformation to such electromagnetic systems, producing equations correct to first order in v/c. Here, we describe an alternate method of obtaining the approximate field transformations, beginning with circular motion in a uniform B field. The basis of our technique is that a Galilean transformation applied to a circular trajectory produces a cycloid. We also show how this method can be visualized using well-known simulation software. Students in lower division general physics can carry out the resulting lab exercise. Although relativity is taught in upper division electrodynamics, in the lower division, it is usually placed with ``modern physics'' in the third semester of a three-semester sequence of general physics. This class is generally taken after students have completed electrodynamics. We advocate bringing relativity back into lower division electrodynamics, since Einstein showed this to be the natural route to relativity. [Preview Abstract] |
Saturday, October 29, 2016 2:12PM - 2:24PM |
S4.00002: Community College as a Sending Out Place to World Renowned Research Centers Sewan Fan During the past six years, we have provided research training and mentoring for STEM students at Hartnell College. Through the support of awards from the US Department of Education, students carried out in depth physics research projects during 8 weeks in the summer at the Hartnell College campus. After their research experience, a number of Hartnell students received further research work and training experience at Stanford University, IBM Research and Department of Energy Labs such as Lawrence Berkeley National Lab, Fermilab and Oak Ridge National Lab. At this conference, we would describe our efforts in training and practically preparing students from a community college to work and contribute at world renowned research centers. [Preview Abstract] |
Saturday, October 29, 2016 2:24PM - 2:36PM |
S4.00003: Multivariate Dependence Beyond Shannon Information Ryan James Accurately determining dependency structure is critical to discovering a system’s causal organization. We recently showed that the transfer entropy fails in a key aspect of this—measuring information ﬂow—due to its conﬂation of dyadic and polyadic relationships. We extend this observation to demonstrate that this is true of all such Shannon information measures when used to analyze multivariate dependencies. This has broad implications, particularly when employing information to express the organization and mechanisms embedded in complex systems. Here, we do not suggest that any aspect of information theory is \emph{wrong}. Rather, the vast majority of its informational measures are simply inadequate for determining the meaningful dependency structure within joint probability distributions. Therefore, such information measures are inadequate for discovering intrinsic causal relations. We close by demonstrating that such distributions exist across an arbitrary set of variables. [Preview Abstract] |
Saturday, October 29, 2016 2:36PM - 2:48PM |
S4.00004: Occam's Quantum Strop John Mahoney, Cina Aghamohammadi, James Crutchfield A stochastic process's statistical complexity stands out as a fundamental property: the minimum information required to synchronize one process generator to another. How much information is required, though, when synchronizing over a quantum channel? Recent work demonstrated that representing causal similarity as quantum state-indistinguishability provides a quantum advantage. We generalize this to synchronization and offer a sequence of constructions that exploit extended causal structures, finding substantial increase of the quantum advantage. We demonstrate that maximum compression is determined by the process's cryptic order---a classical, topological property closely allied to Markov order, itself a measure of historical dependence. We introduce an efficient algorithm that computes the quantum advantage and close noting that the advantage comes at a cost---one trades off prediction for generation complexity. [Preview Abstract] |
Saturday, October 29, 2016 2:48PM - 3:00PM |
S4.00005: The Time-dependent Aharonov-Casher Effect Jaryd Ulbricht, Douglas Singleton We approximate the Lagrangian for a particle of neutral charge with a non-zero magnetic moment by introducing a Pauli spin coupling to the free particle Dirac Lagrangian. Through the use of spinor projection operators we separate the Lagrangian into two non-interacting components that effectively couple to the electromagnetic fields minimally. In the absence of classical forces the coupling results in the neutral particle wavefunction acquiring an additional phase that, in the low velocity limit, reproduces the Aharonov-Casher phase, which is measurable in interference experiments. We use this covariant expression for the Aharonov-Casher phase to investigate the case where the particle is moving in \textit{time dependent} electric and magnetic fields of a plane electromagnetic wave background. We focus on the case where the magnetic moment of the particle is oriented so that both the electric and magnetic fields lead to non-zero phases. We find that time dependent corrections to the phase appear at second order, due to a cancellation of first order corrections. [Preview Abstract] |
Saturday, October 29, 2016 3:00PM - 3:12PM |
S4.00006: Maxwell's Demon Dynamics: Deterministic Chaos in Physical Information Processing Alec Boyd Information processing allows for the extraction of work from a thermal reservoir, as demonstrated by Maxwell's Demons. However, this apparent violation of the second law of Thermodynamics is avoided by recognizing the balancing energetic cost of information processing. This cost was thought to be captured by the energetic cost of erasure, described by Landauer's Principle. However, results in the past decade show that erasure is not the sole culprit, and that Landauer's Principle can be fudged. We introduce a new explicit construction of the Szilard engine, a 1-bit Maxwellian Demon, where energetic costs are exactly calculable for all information processing steps, which illustrates the flexibility of information processing bounds. This new construction allows us to represent the Szilard engine by a deterministic chaotic system---the Szilard Map--- that encapsulates the measurement, control, and erasure protocol by which Maxwell's Demons extract work from a thermal reservoir. The map's degree of chaos is proportional to the energy extraction during control. [Preview Abstract] |
Saturday, October 29, 2016 3:12PM - 3:24PM |
S4.00007: Computational Mechanics of Coherent Structures in Spatiotemporal Systems Adam Rupe, James P. Crutchfield The use of computer simulation and numerical solutions have become common for handling increasingly complex mathematical models of physical phenomena. This has been most successful in nonlinear systems where analytic solutions are scarce, as exemplified by the discovery of deterministic chaos. As attention moves to higher dimensional systems, gaining insight from numerical solutions is no longer trivial. In particular, systems in which simple interactions propagate in a complicated manner to produce complex emergent behavior present serious difficulties for traditional mathematical analysis. Such difficulties are similar to those faced in the theory of computation. Thus a new approach to complex systems, computational mechanics, has been developed that employs the mathematical structures of computation theory to build intrinsic representations of temporal behavior, rather than relying solely on the equations of motion. A rigorous theory of coherent structures in fully discrete classical field theories using computational mechanics is given. The method is demonstrated on the simplest such systems that support emergent structures, namely elementary cellular automata. Results are compared with a similar, but distinct, approach using invariant sets of dynamical systems theory. [Preview Abstract] |
Saturday, October 29, 2016 3:24PM - 3:36PM |
S4.00008: Whither High-Tc 30 Years Following Its Discovery? Challenges Facing the Path Forward for High Temperature Superconductivity from Its Fundamental Understanding to Eventual Societal Deployment Paul Grant It is now 30 years since Georg Bednorz at IBM Zurich, first glimpsed what became known as ``high temperature superconductivity'' near 30 K in a mixed perovskite phase comprising lanthanum, barium, copper and oxygen derived from compounds first formulated at the University of Caen, Normandy, France. This discovery earned Bednorz, and his colleague K. Alex Mueller, the 1987 Nobel Prize in Physics. Their 1986 results had already been verified by a number of other institutions worldwide, as well as the finding of a related copper oxide perovskite with a transition temperature at 91 K, well above the boiling point of liquid nitrogen of 77 K, by Paul Chu and his collaborators at the Universities of Houston and Alabama, later that same year. These revelations set off worldwide speculation focusing on the basic physics underlying its origins, as well as their possible applications within the global electricity enterprise. Today, three decades later, many issues still remain open concerning both their basic understanding and eventual commercial uses. In this talk, we will address these matters by presenting a number of challenges for the emerging generation of young physicists, materials scientists and engineers to consider tackling within their future careers. [Preview Abstract] |
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