Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session B18: Apker Award SessionInvited Live Prize/Award
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Sponsoring Units: DCMP Chair: Nate Stern, Northwestern University |
Monday, March 15, 2021 11:30AM - 12:06PM Live |
B18.00001: LeRoy Apker Award (2019): Dynamics of the Outer Solar System, from Neptune to Planet Nine Invited Speaker: Tali Khain The Kuiper belt, found beyond the orbit of Neptune, consists of a population of small, icy bodies that orbit the Sun. Due to perturbations from the giant planets (Jupiter, Saturn, Uranus, Neptune), the orbits of these objects slowly evolve with time. In this talk, we will analyze the orbital dynamics of the Kuiper belt objects (KBOs) both with numerical simulations and with a theoretical Hamiltonian approach. We will discuss the structure of the outer Solar System and focus on the most extreme sub-population of objects: the long-period high eccentricity class. The orbits of these extreme KBOs all appear to point in the same direction in physical space; this anomalous signal cannot be explained by the currently known eight-planet Solar System. In order to understand their origin and dynamics, we introduce the hypothesized Planet Nine to the distant Kuiper belt. We find that the presence of Planet Nine allows for two stable populations of objects - the aligned and anti-aligned KBOs - in agreement with observations. We will discuss the mechanisms that lead to this stability, and focus on a fascinating process called resonance hopping, in which a KBO rapidly transitions from one resonance to another with Planet Nine. By tying together studies of observed KBOs with more general analyses of the evolution of synthetic test particles, we elucidate the dynamics of the outer Solar System in and out of the Planet Nine context. |
Monday, March 15, 2021 12:06PM - 12:42PM Live |
B18.00002: LeRoy Apker Award (2020): Stochastic resonance enhancement of the resolution of charge coupled device based thermoreflectance imaging Invited Speaker: Elise Koskelo CCD-based thermoreflectance imaging is a non-contact, high spatial resolution technique used in a wide range of applications, including monitoring thermal lensing in lasers, the performance of photovoltaics, and defects in optoelectronics. A 4-bucket algorithm is used to perform pixel-by-pixel lock-in averaging to measure the relative change in reflectance of a sample in response to an induced thermal modulation. Prior experiments demonstrated that the technique can measure signals below the quantization limit of the camera; this enhanced resolution is posited to be due to stochastic resonance, where measurement noise dithers the signal over many bit levels. Here, we develop an experimentally validated analytical and computational model of the stochastic resonance in this system, investigating how measurement noise, when combined with the averaging required by the imaging algorithm, can be used to maximize the thermal resolution. We show that noise is required to obtain accurate thermoreflectance measurements and that in the absence of noise, the A-D conversion of the camera can lead to measurement errors. By tuning experimental parameters, stochastic resonance can be achieved for any noise level, enabling an order of magnitude or greater enhancement in the thermal resolution. |
Monday, March 15, 2021 12:42PM - 1:18PM Live |
B18.00003: LeRoy Apker Award (2020): The strange, but not-so-bad, metallic state of the electron-doped cuprates Invited Speaker: Nicholas Poniatowski The nature of the metallic state of the cuprate high-temperature superconductors remains one of the most pressing open problems in condensed matter physics. In this talk, we will discuss the transport phenomenology of electron-doped cuprates, which proves to be much richer than the mere existence of the linear-in-temperature resistivity for which hole-doped cuprates are notorious. Beyond exhibiting this hallmark of “strange metallicity” at low temperatures, electron-doped cuprates display a number of anomalous transport behaviors throughout the temperature, doping, and magnetic field phase diagram [1,2,3]. In addition to outlining this phenomenology, we present the recent observation [4] of resistivity saturation near the putative Mott-Ioffe-Regel limit in an electron-doped cuprate. We discuss the implications of this result with respect to postulated “bad metallic” or incoherent metallic transport, and its potential relationship to the physics of hole-doped cuprates and other strongly correlated materials. |
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