Events During the Week of July 6th through July 13th, 2025
Monday, July 7th, 2025
- Graduate Program Event
- Cross Correlation of IceCube Neutrinos with Tracers of Large Scale Structure
- Time: 11:00 am - 1:00 pm
- Place: 5280 CH
- Speaker: David Guevel, Physics PhD Graduate Student
- Abstract: Multi-messenger astrophysics aims to study energetic astrophysical environments using physical channels that have historically been inaccessible. Technological developments have created new opportunities to detect neutrinos, cosmic rays, and gravitational waves from distant astrophysical environments. Neutrinos are unique among these messengers because they are produced in large numbers in energetic environments and because they propagate through interstellar and intergalactic space with little interaction along the way preserving the information about their sources. The IceCube Neutrino Observatory has discovered astrophysical neutrinos from extragalactic, and galactic sources and unresolved background sources. The accelerators that produce the energetic extragalactic neutrinos likely trace the large-scale structure, so the diffuse astrophysical neutrino flux may exhibit anisotropy similar to other large-scale structure tracers though no anisotropy has been detected in the diffuse neutrino flux. Galaxies, detected in infrared observations, are well-suited to be used as tracers of large-scale structure. This thesis presents a two-point angular cross-correlation between IceCube neutrinos and an infrared galaxy catalog. This angular correlation required novel modifications to include the effects IceCube's declination and energy dependent effective area and point spread function while also accounting for multipole coupling caused by the use of a galactic plane mask. Despite improvements in the sensitivity to anisotropy, no statistically significant correlation was observed. The upper limit on the correlation strength is used to place constraints on the share of the diffuse neutrino flux that can be contributed from source correlated with the local large-scale structure. If the neutrino spectral energy distribution follows a power law with a spectral index held fixed to the diffuse muon neutrino measurement, the correlated sources can contribute no more than 54% of the diffuse muon neutrino flux. The correlation upper limit rules out nearby source populations while allowing more distant evolution models, such as those tracing the star-formation rate. The next generation of ice Cherenkov detectors such as IceCube Gen2 will be capable of constraining the correlation with three times the precision and potentially detecting anisotropy in the diffuse neutrino flux.
- Host: Ke Fang
Tuesday, July 8th, 2025
- No events scheduled
Wednesday, July 9th, 2025
- Social Gathering
- Summer Recess
- Time: 12:30 pm - 1:00 pm
- Place: Bascom Hall in front of Birge Hall
- Speaker: Everyone is welcome
- Abstract: If the weather is nice, we'll meet on Bascom Hill (in front of Birge Hall). Feel free to bring your lunch. We will borrow cornhole and ladder toss from the L&S Dean's Office and play outside for 30 minutes. Some of us will probably walk up together, meeting in the courtyard between Chamberlin and Sterling ~12:25. Feel free to walk with us! No need to sign up. Just come join us!
- Host: Sharon Kahn
Thursday, July 10th, 2025
- R. G. Herb Condensed Matter Seminar
- One-dimensional interacting topological phases: a bosonization approach
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Polina Matveeva, UMN
- Abstract: I will talk about the topological properties of one-dimensional interacting fermionic phases.
In the first part of my talk, I will discuss the properties of fermionic microscopic models built from two coupled Su-Schrieffer-Heeger chains. We showed that such a system realizes all possible Altland-Zirnbauer symmetry classes. I will briefly discuss some general properties of these chain models that do not directly follow from the non-interacting classification table. In particular, we demonstrated that the non-interacting models that belong to Z classes can be adiabatically deformed into one another without changing the topological invariant as long as chiral symmetry is preserved. As a next step, I will discuss the effects of weak interactions on the topological properties of these chain models using bosonization and show that the chiral symmetry protects topology also in the interacting case.
In the second part of my talk, I will switch to a microscopic model of strongly interacting spinful fermions, where the gap is opened due to interactions. I will discuss the non-trivial topological properties of both insulating and metallic phases that emerge at the critical lines between gapped phases. I will discuss how these phases relate to and differ from single-particle topological phases. - Host: Alex Levchenko
- Atomic Physics Seminar
- Microcavity Photonic Interfaces for Neutral Atom Quantum Computing
- Time: 1:00 pm - 2:30 pm
- Place: Chamberlin 5310
- Speaker: Dr. Brandon Grinkemeyer, Harvard University
- Abstract: Neutral atom qubits trapped in optical tweezers are a promising platform for quantum information processing, with control over several hundred qubits already demonstrated. Further scaling could be significantly enhanced by coupling these systems to optical interfaces, enabling quantum networking and fast, non-demolition readout for quantum error correction. In this talk, I will discuss our progress toward developing a photonic interconnect for large-scale neutral atom quantum processors. Specifically, I will present the strong coupling of single atoms to fiber Fabry-Perot cavities and how this interaction can be harnessed for quantum information processing. Additionally, I will introduce novel, scalable fabrication techniques for high-finesse microcavities and ongoing efforts to integrate them with atom arrays.
- Host: Mark Saffman
Friday, July 11th, 2025
- No events scheduled