Volumes of Space as Subsystems

Understand

As a novel approach with possible relevance to semiclassical gravity, we propose to define regions of space as quantum subsystems.

• After recalling how to divide a generic quantum system into ``parts'', we apply this idea to a free scalar field in Minkowski space and we compare two different localization schemes.
• The first scheme is the standard one, induced by the local relativistic fields; the alternative scheme that we consider is the one induced by the Newton-Wigner operators.
• If degrees of freedom are divided according to the latter, the Hamiltonian of the field exhibits a certain amount of non-locality.