Bulletin of the American Physical Society
Mid-Atlantic Section Meeting 2021
Volume 66, Number 18
Friday–Sunday, December 3–5, 2021; Rutgers University, New Brunswick, New Jersey
Session A01: Welcome and Plenary Session |
Hide Abstracts |
Chair: Sang Wook Cheong, Rutgers University; A. Rualdo Soto-Chavez, New Jersey Institute of Technology Room: Livingston Hall |
Friday, December 3, 2021 2:30PM - 3:30PM |
A01.00001: Axion insulators and surface quantum point junctions Invited Speaker: David Vanderbilt Axion insulators are materials in which inversion, or another magnetic symmetry other than simple time reversal, quantizes the formal Chern-Simons magnetoelectric coupling to a half-quantum value of pi. The surfaces of axion insulators need not be metallic, and when gapped, they exhibit a half-quantized surface anomalous Hall conductivity (AHC) and dissipationless chiral edge channels at 1D boundaries between surfaces of different sign of the AHC. While 3D materials realizations are still an object of active search, I will look ahead to discuss future opportunities presented by such materials. In particular, I will focus on the fact that chiral channels can be associated either with steps or with antiferromagnetic domain walls, opening the opportunity to form novel quantum point junctions at the intersections of the chiral channels. I will also show how the quantum scattering at the junction can be mapped, in principle, onto the physics of qubits, and point out how such gates might be controlled by surface scanning probe tips.\\ \\Nicodemos Varnava, Justin H. Wilson, J. H. Pixley, and David Vanderbilt, "Controlling a quantum point junction on the surface of an antiferromagnetic topological insulator," Nature Communications 12, 3998 (2021).\\ \\In collaboration with Nicodemos Varnava, Justin Wilson, and Jedediah Pixley from Rutgers University. [Preview Abstract] |
Friday, December 3, 2021 3:30PM - 4:30PM |
A01.00002: Dynamics of solar flares with microwave imaging spectroscopy Invited Speaker: Gregory Fleishman Release of magnetic energy due to reconnection is believed to drive such transient phenomena as solar flares, eruptions, and jets. This energy release should be associated with a decrease of the coronal magnetic field. Quantitative measurements of the evolving magnetic field strength in the corona are required to find out where exactly and with what rate this decrease takes place. The only available methodology capable of providing such measurements employs microwave imaging spectroscopy of gyrosynchrotron emission from nonthermal electrons accelerated in flares. Here, we report microwave observations of a solar flare, showing spatial and temporal changes in the coronal magnetic field at the cusp region; well below the nominal reconnection X point. The field decays at a rate of \textasciitilde 5 Gauss per second for 2 minutes. This fast rate of decay implies a highly enhanced, turbulent magnetic diffusivity and sufficiently strong electric field to account for the particle acceleration that produces the microwave emission. Moreover, spatially resolved maps of the nonthermal and thermal electron densities derived from the same microwave spectroscopy data set allow us to detect the very acceleration site located within the cusp region. The nonthermal number density is extremely high, while the thermal one is undetectably low in this region indicative of a bulk acceleration process exactly where the magnetic field displays the fast decay. The decrease in stored magnetic energy is sufficient to power the solar flare, including the associated eruption, particle acceleration, and plasma heating. We discuss implications of these findings for understanding particle acceleration in solar flares and in a broader space plasma context. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700