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Let $C$ be a complex smooth projective curve. We consider the set of parabolic de Rham bundles over $C$ (with rational weights in parabolic structure). Many examples arise from geometry: let $f: X\to U$ be a smooth projective morphism over some nonempty Zariski open subset $U\subset C$. Then the Deligne–Iyer–Simpson canonical parabolic extension of the Gauss–Manin systems associated to $f$ provides such examples. We call a parabolic de Rham bundle \emph{motivic}, if it appears as a direct summand of such an example of geometric origin. It is a deep question in the theory of linear ordinary differential equations and in Hodge theory, to get a characterization of motivic parabolic de Rham bundles. In this talk, I introduce another subcategory of parabolic de Rham bundles, the so-called \emph{periodic} parabolic de Rham bundles. It is based on the work of Lan–Sheng–Zuo on Higgs-de Rham flows, with aim towards linking the Simpson correspondence over the field of complex numbers and the Ogus–Vologodsky correspondence over the finite fields. We show that motivic parabolic de Rham bundles are periodic, and conjecture that they are all periodic parabolic de Rham bundles. The conjecture for rank one case follows from the solution of Grothendieck–Katz p-curvature conjecture, and for some versions of rigid cases should follow from Katz’s work on rigid local systems. The conjecture implies that in a spread-out of any complex elliptic curve, there will be infinitely many supersingular primes, a result of N. Elkies for rational elliptic curves. Among other implications of the conjecture, we would like to single out the conjectural arithmetic Simpson correspondence, which asserts that the grading functor is an equivalence of categories from the category of periodic parabolic de Rham bundles to the category of periodic parabolic Higgs bundles. This is a joint work in progress with R. Krishnamoorthy.

Zoom: https://harvard.zoom.us/j/94717938264

Despite the importance of intangibles in today’s economy, current standards prohibit the capitalization of internally created knowledge and organizational capital, resulting in a downward bias of reported assets. As a result, researchers estimate this value by capitalizing prior flows of R&D and SG&A. In doing so, a set of capitalization parameters, i.e. the R&D depreciation rate and the fraction of SG&A that represents a long-lived asset, must be assumed. Parameters now in use are derived from models with strong assumptions or are ad hoc. We develop a capitalization model that motivates the use of market prices of intangibles to estimate these parameters. Two settings provide intangible asset values: (1) publicly traded equity prices and (2) acquisition prices. We use these parameters to estimate intangible capital stocks and subject them to an extensive set of diagnostic analyses that compare them with stocks estimated using existing parameters. Intangible stocks developed from exit price parameters outperform both stocks developed by publicly traded parameters and those stocks developed with existing estimates. (Joint work with Ryan Peters and Sean Wang.)

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Zoom: https://harvard.zoom.us/j/99205941390

The Clifford group is the most important set of quantum circuits that allow for an efficient classical description. It therefore forms an integral part of many protocols in quantum information, and it turns out that their properties can often be described in terms of representation-theoretic data. Motivated by these connections, we start our analysis by establishing an analogue of Schur-Weyl duality. As is the case for SW-duality between U(d) and  S_t the resulting description of the t^th tensor power of the n-qubit Clifford group is independent of the number n of qubits! This uniform theory implies that, maybe surprisingly, several tasks in quantum information theory can be performed with a system-size independent amount of resources. Examples include: Testing whether an unknown state is a stabilizer state, and constructing unitary designs with few non-Clifford gates.

Zoom: https://harvard.zoom.us/j/779283357

Topological qauntum field theory(TQFT) is a very powerful theoretical tool to study topological phases and phase transitions. In 2 + 1D, it is well known that the Chern-Simons theory captures all the universal topological data of topological phases, e.g., quasi-particle braiding statistics, chiral central charge and even provides us a deep insight for the nature of topological phase transitions. Recently, topological phases of quantum matter are also intensively studied in 3 + 1D and it has been shown that loop like excitation obeys the so-called three-loop-braiding statistics. In this talk, I will discuss a TQFT framework to understand the quantum statistics of loop like excitation in 3 + 1D. Most surprisingly, this new class of 3+1D TQFT even provides us a new route towards understanding quantum gravity. I will also discuss a generalized Einstein equation which might naturally include dark matter sector.

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Zoom: https://harvard.zoom.us/j/977347126

Dualities play an important role in both quantum field theories and condensed matter systems. They can map hard-to-solve, interacting theories to free, non-interacting ones often trigger a deeper understanding of the systems to which they apply. Recently, a web of (non-supersymmetric) dualities has been discovered in 2+1 dimensions inspired by novel developments in topological phases of matter.

In this talk, I will present some extensions of the original 2+1-dimensional fermion-fermion duality in 3+1 dimensions and in presence of axial gauge fields. By employing the slave-rotor approach in the lattice, I will show the central role of the Kalb-Ramond field and chiral anomaly in their formulation. Finally, I will present some applications of these novel dualities in topological systems such as Weyl and Dirac semimetals and non-symmorphic topological insulators.

Zoom: https://harvard.zoom.us/j/977347126