In this article, we address the problem of how temperature of a quantum system is observed. By proposing a thought experiment, we argue that temperature must be conceived as an operator and its measurement must necessarily accompany a collapse in the wavefunction. We model a temperature measurement device and determine the expectation value and quantum uncertainty of its readout. Lastly, we explore the consequences of this point of view and propose an experiment to verify if temperature is indeed a quantum observable. * dvural@nd.edu arXiv:1708.09374v3 [quant-ph]

Many physical, biological and social phenomena can be described by cascades taking place on a network. Often, the activity can be empirically observed, but not the underlying network of interactions. In this paper we offer three topological methods to infer the structure of any directed network given a set of cascade arrival times. Our formulas hold for a very general class of models where the activation probability of a node is a generic function of its degree and the number of its active neighbors. We report high success rates for synthetic and real networks, for several different cascade models.

No abstract