Prof. Gregory A. Fiete, Northeastern University

Nonlinear optical probing and control of magnetic and electronic quantum geometry

Illuminating a material with light can reveal both interesting aspects of electronic and lattice degrees of freedom, as well as drive phase and topological transitions in the material itself. In this talk, I will focus on three distinct responses of a material to light: (1) Nonlinear phononic control of magnetism in bilayer CrI , MnBi Te , and MnSb Te. (2) The non-linear photogalvanic response of Weyl semimetals with tilted cones and chiral charge up to 4 (the largest allowed in a lattice model), as well as the topological superconductor candidate 4Hb-TaS , and (3) The coupling of phonons to electronic degrees of freedom to produce chiral phonons with large g factors of order 1, which can be measured with Raman scattering.  I will discuss how these nonlinear responses are related to the underlying quantum geometry of the Bloch states and present a perspective on interesting frontiers in out-of-equilibrium quantum materials.

Prof. Felix Ringer, Stony Brook University

From Qubits to Quarks: Quantum Computing Meets Nuclear Physics

The strong force in nature, described by the theory of quantum chromodynamics (QCD), governs the interaction of quarks and gluons, which constitute the main building blocks of the visible universe. Since its development over five decades ago, various fundamental questions have remained unanswered despite significant theoretical and experimental efforts: How do the dynamics of quarks and gluons give rise to emergent structures such as nucleons and nuclei? What is the phase diagram of nuclear matter, and what are the real-time and non-equilibrium dynamics at collider experiments and in the early universe? While significant progress has been made on the theory side using perturbative techniques and lattice QCD, the answers to some of the most challenging questions are expected to be beyond the capabilities of classical computing. Advances in quantum computing coupled with the development of innovative algorithms motivate the exploration of quantum simulations to address these questions. In this talk, I will discuss recent progress toward quantum simulations for fundamental particle and nuclear physics, covering both discrete (qubit) and continuous variable (qumode) approaches.

Prof. Hal Haggard, Bard College

Falling Cats, Tunneling of Quantum Geometries, and Quantum Gravity

After his departure, a legend began to build about Maxwell’s time at Trinity College, Cambridge. The story went that he would toss cats from school windows to watch them land upright on their padded paws. (This was not so.) I will describe the true fascination that Maxwell, and many physicists after him, have had with falling cats. Indeed, a falling cat is a remarkably accessible example of a gauge theory and turns out to be mathematically identical to a model of the simplest grain of space used in loop quantum gravity. Insights garnered from this model are allowing us to create detailed pictures of the tunneling of quantum geometry in quantum gravity. This new realm of application for quantum tunneling is unexpected and rich, already lending new perspectives on quantum gravity. I aim to build upon these simpler models to describe the late stages of the evaporation of black holes and the possibility of their quantum metamorphosis into white holes.

Jeffrey McKaig, George Mason University

Why Are Optical Coronal Lines Faint in Active Galactic Nuclei?

Forbidden collisionally excited optical atomic transitions from high ionization potential (IP~54eV) ions (e.g., Ne4+, Fe10+, Ar10+), are known as optical coronal lines (CLs). The spectral energy distribution (SED) of active galactic nuclei (AGN) typically extends to hundreds of electron volts and above, which should be able to produce such highly ionized gas. However, optical CLs are often not detected in AGN using large scale optical surveys such as the SDSS. In this talk I will present recent photoionization calculations with the Cloudy spectral synthesis code which determine possible reasons for the rarity of these optical CLs. I will report on the observability of optical CLs given the dust content and metallicity of the gas, as well as the ionizing slope of the incident AGN SED. Our main conclusions are (1) dust reduces the strength of most CLs by ~three orders of magnitude, primarily as a result of depletion of metals onto the dust grains. (2) In contrast to the CLs, the more widely observed lower IP optical lines such as [O III] 5007A, are less affected by depletion and some are actually enhanced in dusty gas. (3) In dustless gas many optical CLs become detectable, and are particularly strong for a hard ionizing SED. This implies that prominent CL emission likely originates in dustless gas. I will also present recent work our group has conducted which indeed suggests dust is being destroyed in objects with CL emission and may indicate an important stage in AGN host-galaxy evolution.

Dr. Todd Martinez, Stanford University

Title and abstract TBA

UConn Particles, Astrophysics, and Nuclei Seminar Series.

Dr. Neill Warrington, MIT (Title and abstract forthcoming)

Contact: Prof. Gerald Dunne