Search Talks

If a pure quantum state is drawn at random, this state will almost surely be almost maximally entangled. This is a well-known example for the "concentration of measure" phenomenon, which has proved to be tremendously helpful in recent years in quantum information theory. It was also used as a new method to justify some foundational aspects of statistical mechanics. In this talk, I discuss recent work with David Gross and Jens Eisert on concentration in the set of pure quantum states with fixed mean energy: We show typicality in this manifold of quantum states, and give a method to evaluate expectation values explicitly. This involves some interesting mathematics beyond Levy's Lemma, and suggests potential applications such as finding stronger counterexamples to the additivity conjecture.

Most often, the dark matter puzzle is analyzed along a single perspective, thus trying to answer a single question. Either "what is the dark matter?", focusing on its microscopic nature, or "how is dark matter distributed in the universe?" focusing on the large scale structure of the universe, or still "how does it affect what we observe in the sky?". Both my scientific interests and some random fluctuations at the beginning of my career have conspired so that I would take on projects in all these fields. Leaving aside the ambition -- and the impossible task -- to be comprehensive, I will review some interesting aspects of these fields and some of my contributions, ranging from using astrophysical cross-correlations to put constraints on the neutrino masses, to the interplay between Higgs searches at colliders and dark matter experiments, to using gamma ray observations to detect and measure properties of extra dimensions.

CMB measurements reveal a very smooth early universe. We propose a mech- anism to make this smoothness natural by weakening the strength of gravity at early times, and therefore altering which initial conditions have low entropy.