Sommerfeld Lecture Series (ASC)

The density of states of a unitary quantum field theory is known to have a universal behavior at high energy. In two dimensions, this behavior is described by the Cardy formula. When the theory has symmetry, it is interesting to find out how the Hilbert space is decomposed into irreducible representation of the symmetry. In this talk, I will derive universal formulas for the decomposition of state...

Recent experiments suggest the phenomenon of light induced superconductivity above Tc in two different materials: fullerene superconductor K3C60 and high Tc cuprate YBCO. I will discuss the distinct phenomena taking place in these systems. In K3C60, the unusual character of electron-phonon interactions results in enhanced BCS pairing through optical driving and the slow relaxation of superconduct...

It is commonly recognized that scientific discoveries result in new technologies. In this talk we will discuss the reverse: behind every conceptual breakthrough lies some technological advance. To illustrate this point, we will review how modern progress in optical technologies is revolutionizing our understanding of quantum matter. We will discuss experiments that showed that we can optically con...

In this talk, I will discuss the applications of cavity electrodynamics for controlling many-body electron systems. The focus will be on achieving strong coupling between cavities and collective excitations of interacting electrons at Terahertz and IR frequencies. As a specific example I will consider a cavity platform based on a two dimensional electronic material encapsulated by a planar cavity...

Materials science has always balanced on the twin pillars of observation and abstraction—from the alchemists’ crude recipes to today’s AI-driven materials design. In this talk, we begin by revisiting the pre-quantum era, when early chemists grappled with the nature of elements and compounds, and examine how Mendeleev’s periodic table first imposed order on the chemical world. We then show that wha...

We will review the beginning of experimental and theoretical studies of moire systems and their evolution up to present. This type of systems represent a new way of “growing” materials, and has tremendous potential both for fundamental physics as well as for applications. Two dimensional periodic crystals, whose separation between atoms is of order angstroms, can be twisted controllably with respe...

I will show how a new set of twisted materials based on the M point rather than the K point can realize a series of exotic phases of matter, including quantum spin liquids and charge glasses. These materials, which have been exfoliated and twisted experimentally, will be at the forefront of new moire discoveries.

We start by describing the geometrical notions central to Einstein's theory of gravity. We then discuss current ideas for how spacetime geometry could emerge in a quantum theory of gravity. We will see that quantum entanglement plays a crucial role.

Euclidean gravity on a sphere (euclidean de-Sitter) gives rise to some phase factors. We discuss how these phase factors change when we include an observer. We also discuss situations involving products of spheres.