Talks

Many interesting spaces arise as Coulomb branches of 3d N=4 quiver gauge theories, including nilpotent orbit closures and affine Grassmannian slices. These interesting spaces often admit interesting embeddings into one another. For example, one nilpotent orbit closure might be contained inside another. That said, it is much less clear how to describe or construct such an embedding from a purely Coulomb branch perspective. I will discuss joint work with Dinakar Muthiah, where we describe a natural Coulomb branch connection with Coulomb branches: for finite ADE types, the embeddings respect monopole operators thought of as functions on the Coulomb branch. This perspective also allows us to generalize the story, and construct embeddings for arbitrary quivers which have the same property.

I will present a universal numerical tool for identifying optimal adaptive metrological protocols in the presence of both uncorrelated and correlated noise [arXiv:2403.04854]. Leveraging a novel tensor network decomposition of quantum combs, the algorithm demonstrates efficiency even with a large number of channel uses (N=50). In the second part of the talk, I will explore the generalization of existing metrological upper bounds [Nat. Com. 3, 1063 (2012), PRL 131(9), 090801 (2023)] for correlated noise scenarios [arXiv:2410.01881].

The Ryu-Takayanagi (RT) formula was originally introduced to compute the entropy of holographic boundary conformal field theories. In this talk, I will show how this formula can also be understood as the entropy of an algebra of bulk gravitational observables. Specifically, I will demonstrate that any Euclidean gravitational path integral, when it satisfies a simple set of properties, defines Hilbert spaces associated with closed codimension-2 asymptotic boundaries, along with type I von Neumann algebras of bulk observables acting on these spaces. I will further explain how the path integral naturally defines entropies on these algebras, and how an interesting quantization property leads to a standard state-counting interpretation. Finally, I will show that in the appropriate semiclassical limits, these entropies are computed via the RT formula, thereby providing a bulk Hilbert space interpretation of the RT entropy.

Maturing Pulsar Timing Arrays are expected to inaugurate the era of nano-hertz GW astronomy in the coming days under the auspices of the International Pulsar Timing Array. Implications of ongoing IPTA efforts for astrophysics and cosmology will be discussed while focussing on PTA contributions. Ongoing IPTA efforts should lead to persistent multi-messenger GW astronomy with massive BH binaries especially during the Square Kilometre Array era, and its implications will be discussed.