Abstract: The averaged null energy operator is a light-ray integral of the null energy. This operator is known to be closely tied to causality in AdS/CFT, to deformations of the modular Hamiltonian in quantum field theory, and to the Lorentzian inversion formula in CFT. I will discuss a new connection between averaged null energy and the monotonicity of the renormalization … Read More
Abstract: I will discuss that a four-dimensional de Sitter space, if it exists in string theory, must be an excited state in the low energy effective field theory of string theory and not a vacuum state. I’ll argue that such a state is close to, but not exactly, a coherent state as it differs from it in some subtle way.
Abstract: We study closed cosmologies in simples models of two dimensional gravity. We show that there are stark contrast as well as connections between semi-classical and non-perturbative aspects of the theory of closed universes.
Abstract In the original CPT theorem one is restricted to flat space and is unable to make converse statements. In this talk I will show how we can reformulate the CPT theorem using a symmetry argument and generalise it to beyond flat space. This in turn allows us to make a non-perturbative statement of unitarity in de Sitter. I will … Read More
Abstract: We study black holes in two and three dimensions that have spacelike curvature singularities behind horizons. The 2D solutions are obtained by dimensionally reducing certain 3D black holes, known as quantum BTZ solutions. Furthermore, we identify the corresponding dilaton potential and show how it can arise from a higher-dimensional theory. Finally, we show that the rotating BTZ black hole develops … Read More
It has previously been observed that the evolution of entanglement entropies and OTOCs in systems ranging from random unitary circuits to holographic CFTs can be understood within a common framework known as the “membrane picture.” In this talk, we consider a class of Brownian local evolutions, where the Lorentzian evolution of the system on multiple copies can be equivalently described … Read More
Abstract: How do bulk strings relate to boundary Feynman diagrams? I will give an overview of my work with Rajesh Gopakumar on deriving the closed string dual to the simplest possible gauge theory, a Hermitian matrix integral. Working in the conventional ‘t Hooft limit, we extract topological string theories which replace the minimal string away from the double-scaling limit. We … Read More
Abstract: Nonlocal games are a foundational tool in quantum information and complexity. They give an operational perspective on entanglement, which in turn has led to many protocols in settings with multiple spatially-separated quantum devices. A recent line of work initiated by Kalai et al (STOC’23) investigates to which extent spatial separation can be replaced by timelike separation, by using cryptography. … Read More