**Relativistic quantum reference frames** - Alexander Smith

Progress in physics, from Aristotelian physics, to Galilean and Newtonian physics, and then to both special and general relativity, can be viewed as a continual refinement of the notion of a reference frame. The next natural step in this progression is the idea of a quantum reference frame. In this talk, I will summarize the basic tools that have been developed to study quantum reference frames and examine how they may be applied to relativistic scenarios. In particular we will look at how two observers in different Lorentz frames that are partially correlated can communicate via the exchange of a single massive spin 1/2 particle. We will then examine an approach to quantum reference frames involving a trace over global degrees of freedom, rather than an average over all possible orientations of a system with respect to an external reference frame. This approach is anticipated to help deal with reference frames associated with non-compact groups, such as the Poincaré group.