The brown bag seminar is a weekly meeting organized by and for graduate students. The goal of the brown bag seminar is to encourage students to practice presenting their research among fellow students in a casual setting.
Wednesday, March 4, 2026 1:00 pm
Applied Math Graduate Student Brown Bag Seminar - two speakers
Speaker 1: Jackson Zasriski
Title: Telescope Control Performance Assessment via Record-Based Metrics
Abstract:
We propose a novel combinatorics-based metric for astronomical telescope operations and acquisition offset analysis. In telescope pointing and acquisition pipelines, offset residual time series often contain intermittent spikes caused by changing observing conditions, hardware effects, or other layered relationships in feature space. We interpret our metric, called the DS score, as a rank-based “spike complexity” statistic: lower scores correspond to flatter, less structured residual sequences after model correction, with a theoretical lower bound on the order of measurement noise. This provides a complementary diagnostic to traditional measures, with the advantage of being robust to ordering structure. We discuss practical adaptations for real-valued noisy telemetry in the context of the Tierras telescope, including strict-record definitions, and random-smoothing, and outline how DS layer decompositions can be used to compare raw vs model-corrected offset series in telescope ML workflows. More broadly, the framework offers a mathematically grounded baseline for distinguishing random-order behavior from persistent structured spikes in sequential observatory data.
Speaker 2: Eric Sung
Title: Decoherence and the Reemergence of Coherence From a Superconducting “Horizon”
Abstract: In a recent paper, Danielson et al. demonstrated that the mere presence of a black hole causes universal decoherence of quantum superpositions (dubbed the DSW decoherence) within a finite amount of time. This result has profound implications for the interplay of quantum mechanics and gravity. We analyze decoherence in a superconducting analog of the event horizon of a black hole, where Andreev reflection plays the role of Hawking radiation. We consider a normal metal interferometer threaded by an Aharonov-Bohm flux, where one of the arms of the interferometer is coupled to a superconductor by a tunnel coupling of varying strength. At absolute zero and for weak coupling, we find that the scattering states of the interferometer are decohered by Andreev reflection, a nontrivial manifestation of the proximity effect analogous to DSW decoherence from the event horizon of a black hole. However, for increasing coupling strength to the superconductor, we find a reemergence of coherence via resonant tunneling through Andreev bound states. This suggests the existence of an analogue gravitational phenomenon wherein transmission mediated by virtual Hawking radiation leads to a reemergence of coherence in an interferometer placed within a few Compton wavelengths of a black hole's event horizon. Our results open a new path to study black hole quantum physics on earth via analog studies.