https://www.atmschools.org/school/2019/NCMW/cmrt

The velocity distribution of a gas in thermal equilibrium is known to be a gaussian. What is the distribution for an inelastic gas driven to a steady state through external driving? This is a central question in the kinetic theory of driven granular gases. For driven binary systems, experiments have reported different velocity distributions for the different components. The typical experiment consists of two layers: the bottom layer is driven externally while the top layer is excited by the bottom layer. In this talk, we review the experimental data for binary gases. We then propose a simple microscopic model consisting of a mixture of two types of particles. Assuming the well-mixed limit, we determine analytically the asymptotic behaviour of the velocity distribution for both types of particles for different types of driving mechanism. We show that the tails of the velocity distribution for both types of particles have similar behaviour, even though they are driven differently which run counter to the known result. The talk is based on the preprint ArXiv:1910.07745

https://www.atmschools.org/school/2019/NCMW/cmrt

We take a resource-theoretic approach to the problem of quantifying nonclassicality in Bell scenarios. We conceptualize the resources as probabilistic processes from the setting variables to the outcome variables having a particular causal structure, namely, one wherein the wings are only connected by a common cause. We term them "common-cause boxes". We define the distinction between classical and nonclassical resources in terms of whether or not a classical causal model can explain the correlations. We then quantify the relative nonclassicality of resources by considering their interconvertibility relative to the set of operations that can be implemented using a classical common cause (which correspond to local operations and shared randomness). We prove that the set of free operations forms a polytope, which in turn allows us to derive an efficient algorithm for deciding whether one resource can be converted to another. We moreover define two distinct monotones with simple closed-form expressions in the two-party binary-setting binary-outcome scenario, and use these to reveal various properties of the pre-order of resources, including a lower bound on the cardinality of any complete set of monotones. In particular, we show that the information contained in the degrees of violation of facet-defining Bell inequalities is not sufficient for quantifying nonclassicality, even though it is sufficient for witnessing nonclassicality. Finally, we show that the continuous set of convexly extremal quantumly realizable correlations are all at the top of the preorder of quantumly realizable correlations. In addition to providing new insights on Bell nonclassicality, our work also sets the stage for quantifying nonclassicality in more general causal networks. Based on arXiv:1903.06311

https://www.atmschools.org/school/2019/NCMW/cmrt