Quantum Fields and Strings

While entanglement has been examined extensively in AdS/CFT, it has avoided significant attention in the study of celestial holography and asymptotic symmetries relevant to asymptotically flat spacetime. I will present work that considers the entanglement of a Milne patch for Maxwell theory in Minkowski spacetime from the perspective of celestial holography. In the Minkowski vacuum, we find that the Milne patch is thermally entangled. We interpret the thermal entangling operator that builds the Minkowski vacuum from the Milne vacuum as an interaction term in the celestial CFT. We further examine the edge modes of the Milne patch, assigning them a physical interpretation as fluctuations in Milne asymptotic charge. Interestingly, we find that the constraint governing these edge modes includes sources that avoid the Minkowski interior. Altogether, by studying entanglement along the extra holographic direction present in celestial holography but absent in AdS/CFT, our work bridges a critical gap between our understanding of entanglement in the latter and the physically relevant setting of asymptotically flat spacetime.

Zoom Link: TBD

The holographic duality between strongly coupled quantum field theories and weakly coupled gravitational theories in one higher dimension holds, in principle, the promise of understanding strongly coupled systems that occur in condensed matter physics, such as the "strange" metals that appear in materials such as high-Tc cuprates. Unfortunately, the holographic models of metals that have previously been studied have not been successful in capturing even the most basic physics that any realistic model of a metal should obey. In this talk, I will review the essential properties that any metal (strongly coupled or not) must satisfy, and propose a new holographic model that is consistent with these requirements. The new model is based on a radically different approach compared with previous holographic models of metals, and crucially relies on recent work that formulates in a precise way the conditions for an IR effective field theory to be "emergeable" from a UV theory at nonzero charge density. In particular, the holographic model I study is dual to a quantum field theory with a global symmetry group LU(1) -- the "loop group" whose elements are smooth functions from the circle into U(1). I present the results of a solution of the model and argue that its properties are qualitatively consistent with what one should expect to find in a strongly coupled metal.

Zoom Link: TBD

It has long been known in studies of Pion physics, non-linear sigma models and cosmology that thinking in terms of field space metrics can be useful. Such an approach can help identify and define field redefinition invariant physics in observables. This approach is reemerging recently an a key organizing principle and calculational tool for interpreting collider physics data to study Higgs properties. I will review some known results and discuss outstanding issues being worked on in this area. 

Zoom Link: https://pitp.zoom.us/j/96662488113?pwd=cGs0THQwWXRkcm9pVzcwVytnNjZ5Zz09

For a theory whose half-BPS sector can be described by N=4 quiver quantum mechanics, its BPS algebra (à la Harvey-Moore) is given by the quiver Yangian. I will first review the construction of the BPS quiver Yangians and then discuss their applications, such as on BPS counting, Gauge/Bethe correspondence, and knot-quiver correspondence. 

Zoom Link: TBD

I review a class of quantum error correcting codes that directly takes into account the large-N aspects of holographic theories. I will discuss some aspects of the vacuum sector of these codes and use them to show the equivalence between two different approaches to entanglement wedge reconstruction.

Zoom link:  https://pitp.zoom.us/j/96318197584?pwd=YXJEdkJrVktXVmI3SWVlRmlaK3A4Zz09

Universal properties of two-dimensional conformal interfaces are encoded by the flux of energy transmitted and reflected during a scattering process.

In this talk, I will develop a method that allows me to extend previous results based on thin-brane holographic models to smooth domain-wall solutions of 3-dimensional gravity.

As an application, I will compute the transmission coefficient of a Janus interface in terms of its deformation parameter.

Zoom link:  https://pitp.zoom.us/j/98684574364?pwd=WGdrQXhRcHRJZUZMYmNObUVZT1ZCZz09