CMTC Seminar

Abstract: In solid materials, electrons are usually described by the non-relativistic Schrodinger equationsince electron velocity is much slower than the speed of light. However, the relativisticDirac/Weyl equation can emerge as a low-energy effective theory for electrons in certainmaterials. These systems are dubbed “Dirac/Weyl materials” and provide a tunable platformto test quantum relativistic phenomena in table-top experiments. Owing to the linear-inmomentum form, a variety of physical fields, e.g.

Abstract: I will discuss entanglement quantities in two-dimensional topologically-ordered phases that can potentially capture correlations beyond what bipartite entanglement entropy can. Specifically, I will present the calculations of the reflected entropy and entanglement negativity for topological ground states when we consider two spatial sub regions. I will also discuss applications of these ideas to one-dimensional quantum lattice many-body systems.
Location: ATL 4402

Abstract: We study possible phases and possible continuous phase transitions in systems with a given finite symmetry. We use the corresponding categorical symmetry and its condensable algebras to classify the possible gapped phases and possible gapless critical points, as well as determine the CFT of the critical points in 1+1D.
 
Host: Yu-An Chen
 

Abstract: Fractons are a class of quasiparticles that cannot freely propagate through space. They were first introduced in a model of quantum (almost) self-correcting memory. Later it became clear that fractons, as well as, adjacent ideas such as tensor gauge theories and multipole or subsystem conservation laws provide a language to describe some known and some new phenomena. In this talk I will explain what fractons are, what kind of systems are known to support them and what kind of problems they will help to elucidate in the future.
Location: ATL 4402

Abstract: Magic-angle (θ=1.05∘) twisted bilayer graphene (MATBG) has shown two seemingly contradictory characters: the localization and quantum-dot-like behavior in STM experiments, and delocalization in transport experiments. We construct a model, which naturally captures the two aspects, from the Bistritzer-MacDonald (BM) model in a first principle spirit. A set of local flat-band orbitals (f) centered at the AA-stacking regions are responsible to the localization.

Abstract: Semiconductor moiré materials provide a physical realization of the Kane-Mele-Hubbard model for studies of the combined effects of non-trivial band topology and strong electronic correlations. In this talk, I will discuss the rich electronic phase diagram of the Kane-Mele-Hubbard model realized in AB-stacked MoTe2/WSe2 moiré bilayers.

Abstract: In most common metals, the many-body physics of their electrons can be described in terms of additive, weakly interacting excitations called quasiparticles. However, several examples of metallic states of matter related to the “high” temperature superconductors and other strongly correlated materials exist, in which strong electron-electron interactions near putative quantum critical points or phases lead to very unconventional physics that cannot be described by quasiparticles, even as the electron liquid remains compressible.

Abstract: In the past decade, quantum simulators have increased in their power and scope, offering exquisite dynamical control of tens or even hundreds of individual atoms. Concurrently, a topological revolution in our understanding of electronic band structures has taken place, driven by the discovery of topological insulators, graphene and other topological materials. Remarkably, these advances can be connected --- the dynamics of driven few level systems can be described using band structures in "synthetic dimensions," one per driving tone.

Abstract: Over the last several decades, entanglement has emerged as a unifying lens for understanding phenomena across many areas in quantum physics. At low energy, the structure of ground state entanglement reflects universal features of the phase of matter. At high energy, the growth of entanglement underlies thermalization and the emergence of statistical mechanics. In this talk, I will describe two recent exact results characterizing entanglement in many-body systems.

Abstract: Semiconductor moiré materials provide a physical realization of the Kane-Mele-Hubbard model for studies of the combined effects of non-trivial band topology and strong electronic correlations. In this talk, I will discuss the rich electronic phase diagram of the Kane-Mele-Hubbard model realized in AB-stacked MoTe2/WSe2 moiré bilayers.