Video Library

Theorists have been studying and classifying entanglement in many-particle quantum states for many years. In the past few years, experiments on such states have finally appeared, generating much excitement. I will describe experimental observations on magnetic insulators, ultracold atoms, and high temperature superconductors,  and their invigorating influence on our theoretical understanding.

In this talk, I will discuss about the notion of quantum renormalization group, and explain how (D+1)-dimensional gravitational theories naturally emerge as dual descriptions for D-dimensional quantum field theories. It will be argued that the dynamical gravitational field in the bulk encodes the entanglement between low energy modes and high energy modes of the corresponding quantum field theory.

We will point out that there is a universal thermodynamical property of entanglement entropy for excited states.  We will derive this by using the AdS/CFT correspondence in any dimension. We will also directly confirm this property from direct field theoretic calculations in two dimensions. We will define a new quantity called entanglement density by taking derivatives of entanglement entropy with respect to the shape of subsystem.

The
"psi-epistemic" view is that the quantum state does not represent a
state of the world, but a state of knowledge about the world.  It is
motivated, in part, by the observation of qualitative similarities between
characteristic properties of non-orthogonal quantum wavefunctions and between
overlapping classical probability distributions.  It might be suggested
that this gives a natural explanation for these properties, which seem puzzling
for the alternative "psi-ontic" view.  I will examine two such