News & Events

Evolving Networks in Matter and Mind

Abstract: Networks exist in both physical and conceptual spaces. Those networks can be treated as static and fixed, but in many cases evolve appreciably over a variety of time scales. In this talk, I will discuss the evolution of networks in matter and mind. I will separate my comments into three main sections. First, I will discuss principles by which to design mechanical networks that undergo precise, and pre-defined conformational changes (Kim et al. 2019 Nature Physics; Kim et al. 2022 Phys Rev X, In Press). Second, I will discuss connections between networks of matter and networks of mind, and relations among physical and conceptual spaces (Zurn & Bassett, forthcoming from MIT Press). Third, I will discuss an empirical study of evolving networks of mind, as manifest in how scientists cite the work of other scientists in the reference lists of their peer-reviewed papers (Teich et al. 2022 arXiv, and others), including relative imbalances in how we cite the work of gender, racial, and ethnic minorities. Collectively, the work will provide a conceptual framework for understanding evolving networks in matter and mind, with important implications for our understanding of our physical world and the processes of scientific inquiry.

Abstract: It is well known that a light, pseudo-scalar particle called the Axion can solve several fundamental physics problems.  Proposed to explain the lack of a neutron EDM, such a weakly interacting particle has the right characteristics to explain formation of galaxies, by providing the needed mass in the form of Cold Dark Matter.  There has been a number of completed and proposed experiments to detect axionic particles taking approaches as varied as condense matter energy band gap to superconducting magnetic cavities.  This talk will review the theory behind axion particles, examples of early experimental searches and some new search techniques.  One question this talk will broach, is whether or not observations of nuclear behavior, a place where axionic matter is theorized to play a role in neutron spin, can provide appropriate experimental conditions to be used in axion searches.  
This colloquium will be remote only via zoom:
https://umn.zoom.us/j/94831171860 

Over the past couple decades, thousands of extra-solar planets have been discovered orbiting other stars. The exoplanets discovered to date exhibit a wide variety of orbital and compositional properties; most are dramatically different from the planets in our own Solar System. Our classical theories for the origins of planetary systems were crafted to account for the Solar System and fail to account for the diversity of planets now known. We are working to establish a new blueprint for the origin of planetary systems and identify the key parameters of planet formation and evolution that establish the distribution of planetary properties observed today. The new blueprint must account for the properties of planets in inner solar systems, regions of planetary systems closer to their star than Earth’s separation from the Sun and home to most exoplanets detected to data. I present work combining simulations and theory with data analysis and statistics of observed planets to test theories of the origins of inner solars, including hot Jupiters, warm Jupiters, and tightly-packed systems of super-Earths. Ultimately a comprehensive blueprint for planetary systems will allow us to better situate discovered planets in the context of their system’s formation and evolution, important factors in whether the planets may harbor life. 

Quantum Matter out of Equilibrium

Abstract: A central goal of condensed matter physics is to study the universal emergent properties of macroscopic quantum systems with large numbers of interacting particles. Due to a variety of conceptual and experimentally motivated reasons, the traditional approach of many-body physics is largely built around the study of low-temperature and near-equilibrium properties of time independent Hamiltonians.  A confluence of developments across a range of subfields --- particularly experimental advances in building programmable quantum devices --- have opened up a vast new territory of studying many-body phenomena in completely novel regimes: highly excited, "post Hamiltonian", and far from equilibrium.  A unifying theme in this enterprise has been the study of many-body quantum dynamics in systems ranging from electrons in solids to cold atomic gases to black holes.  I will describe some highlights of an active research program to advance many-body theory beyond the regime of near-equilibrium time-independent Hamiltonians, with a view towards uncovering novel emergent phenomena in the non-equilibrium dynamics of many-body systems. I will show that not only can non-equilibrium systems exhibit a sharp notion of phase structure, but that some of these phases are completely novel and unique to the out-of-equilibrium setting. For example, certain phases of matter that are forbidden in equilibrium, such as quantum time crystals, have found new life in the out-of-equilibrium setting.  I will describe the theoretical formulation of this phase, some of its many fascinating properties, and its recent experimental realization on Google's quantum processor.

Physics Force is back and ready for some fun new shows in January 2022! The auditorium shows will feature all the fun big demos, bringing the wonders of physics to life in an educational and spectacular display.

There will be two public shows: 11:00 a.m. and 2:00 p.m. on Saturday, January 15, 2022.

Intended for all ages, the shows are free and open to the public. Registration/tickets are required.

Physics Force is supported by the School of Physics and Astronomy, the Dean of the College of Science and Engineering, and the University of Minnesota's Materials Research Science and Engineering Center (MRSEC). Physics Force is sponsored by a gift from the 3M Company. 

Organized by Professors Andrey Chubukov, University of Minnesota and Professor Dmitrii Maslov, University of Florida.

Abstract: I was doing pretty well in my particle physics research when something happened to change everything: Former students came back to ask me to work with them in industry. They wanted me to help solve problems using physics skills they knew I had from the classes they took with me. I will detail examples of how we solved problems largely involving the magnetic field physics of MRI, and in performance optimization with rather old-fashioned analytical modeling of hardware coil products. One example is going from the functional analysis of quantum field theory to the manufacturing of optimized gradient magnetic field coils. It will be fun to intersperse stories such as how this industrial problem solving and successful start-up businesses fed back into my teaching, textbook writing, getting jobs for more students in more ways than I can count, and understanding the need for “soft skills.”

This colloquium will have a remote option via zoom:
https://umn.zoom.us/j/94831171860 

Abstract:  When two van der Waals materials of slightly different orientations or lattice constants are overlaid, a moiré pattern emerges. The moiré pattern introduces a new length scale, many times the lattice constant of the original materials, for Bragg scattering of Bloch electrons in each layer.  This gives rise to moiré minibands and rich emergent quantum phenomena. In this talk, I will discuss recent experiments on angle-aligned semiconductor heterobilayers, which exhibit remarkable correlated insulating states [1,2,3]. I will also discuss the prospect of using moiré superlattices as a quantum simulator.  1. Y. Tang et al., Nature 579, 353-358 (2020).
2. Y. Xu et al., Nature 587, 214–218 (2020).
3. C. Jin et al., Nat. Mater. 20, 940-944 (2021). 

Abstract: Examples of granular materials exist in abundance, from rice and cereal to sand and rocks. These particulate systems seem simple; they consist of dry, rigid grains interacting by contact forces. However, granular materials present complexities that are not well-understood, such as disordered force networks that transmit forces among grains and flow behavior that can readily change between solid-like rigidity and fluid-like flow. Impact of a granular target by a solid projectile illustrates both of these aspects. In this talk I will discuss impact experiments in which we use high-speed video photography to probe the unique features of a granular medium.

Zoom and Viewing Party: The speaker will be on Zoom, but WIPA will have a viewing party in Tate 301-20 with coffee, tea, hot chocolate, and stroopwafels. Zoom here: https://sites.google.com/umn.edu/wipaumn/waphls