Physics and Astronomy Calendar

Week of Monday, December 9th 2019

Monday, December 9th 2019
12:15 pm:
Speaker: There will be no seminar this week.

Tuesday, December 10th 2019
11:15 am:
Nuclear Physics Seminar in Tate 301-20
Speaker: Alexander Turbiner from ICN-UNAM, Mexico and Stony Brook University
Subject: "Quantum many-body problem: (Lie)-algebraic aspects"

Many body problem plays a central role in many physics sciences including celestial mechanics, atomic-molecular physics, nuclear physics. Its main characteristics is that the potential in non-relativistic CM and QM depends on relative distances between bodies alone. It is one of the most difficult problems in theoretical physics for more-then-two-body case. Recently, a new concept was proposed: to study solutions of n-body problem which depend on relative distances ALONE. In such a case n-body problem becomes less dimensional and equivalent to either quantum top in constant magnetic field or to multi-dimensional particle moving in curved space with some remarkable cometric. Since the ground state function - the main object in quantum mechanics - and choreography in classical mechanics are functions of relative distances ONLY they can be treated in much simpler way then up to now. Analogue of kinetic energy is (Lie)-algebraic operator which can be
written in terms of sl(n(n+1))/2 algebra generators. Solvable n-body harmonic oscillator might be briefly discussed. Animations of choreography in 3-body Newtonian gravity will be demonstrated. Joint work with W Miller (UMN) and A. Escobar (CRM, Montreal).

1:25 pm:
Space Physics Seminar in Tate 201-20
To be announced
Speaker: Zhi Yang
Subject: Brain Machine Communication

We study and implement emerging brain technologies. In this talk, I will first introduce our research. I will share demos and patient interviews to explain how our research could change their life. I will then discuss the challenges, recent innovations, and the next-step plan towards translating the research into clinical prototypes. Finally, I will present our ongoing works and discuss future directions for innovating the next generation neural modulation technologies and their upcoming human clinical applications in a broader context.

Wednesday, December 11th 2019
09:00 am:
Poster Session for MXPII in Tate Basement Atrium
Everyone welcome to come eat pizza and view the work this semester's MXP II students have accomplished. Event ends at 11:00 a.m.

Xiaohuan Xia, "Studying the Dynamics of a Nonlinear Damped Driven Oscillator"
Caleb Medchill and Adam Presler, "Positron Annihilation and Photon Polarization Entanglement"
Katherine Couteaux and Liam Thompson, "Measuring the Speed of Light using an Open Cavity Helium Neon Laser"

1:25 pm:
Speaker:  Stefano Martiniani, Department of Chemical Engineering & Materials Science, University of Minnesota
Subject: Squeezing order out of disorder

While the equilibrium properties, states, and phase transitions of interacting systems are well described by statistical mechanics, the lack of suitable state parameters has hindered the understanding of non-equilibrium phenomena in diverse settings. I will discuss how Computable Information Density (CID), the ratio of the length of a losslessly compressed data file to that of the uncompressed file, is a measure of order and correlation in both equilibrium and nonequilibrium systems. The technique will be shown to reliably identify nonequilibrium phase transitions, determine their character, quantitatively predict dynamical critical exponents and correlation lengths without prior knowledge of the order parameters. I will show how CID revealed previously unknown ordering phenomena, such as a cascade of phase transitions in the BML traffic model, and a “checkerboard” dynamical instability in the parallel update Manna sandpile model. The scaling of the CID length scales agree well with those computed from the decay of two-point correlation functions g2(r) when they exist. But CID also reveals the correlation lengths scaling when g2(r) = 0, as we demonstrate by “cloaking” the data with a Rudin-Shapiro sequence. If time allows it, I will discuss preliminary results on how we can capture the local entropy production of an active Brownian particles system by compression.

[1] S. Martiniani, P. M. Chaikin, D. Levine, “Quantifying hidden order out of equilibrium”, Phys.
Rev. X, 9, 011031 (2019).

Faculty Host: Jorge Vinals

Thursday, December 12th 2019
12:10 pm:
No Journal Club this week
3:35 pm:
There will be no colloquium this week.

Friday, December 13th 2019
12:30 pm:
There will be no seminar this week.
2:30 pm:
No colloquium this week

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