Speaker
Description
The dynamics of quantum systems in indefinite spacetimes—such as superpositions of macroscopically distinct semiclassical geometries—have been studied extensively in the contexts of quantum reference frames and quantum field theory in curved spacetimes. These studies typically assume that quantum states associated with different spacetimes (i) form a complete orthonormal basis and (ii) possess no intrinsic dynamics. Motivated by arguments from the quantum gravity community, we relax the first assumption and treat different spacetimes as partially distinguishable. This leads to novel dynamical effects arising from the nonorthogonality of spacetime states. We explore the consequences of this framework and predict several new phenomena, including a thought experiment that constrains the inner product between distinct metric states.
