  Using tangent bundle geometry we construct an equivalent reformulation of
classical field theory on flat spacetimes which simultaneously encodes the
perspectives of multiple observers. Its generalization to curved spacetimes
realizes a new type of non-minimal coupling of the fields, and is shown to
admit a canonical quantization procedure. For the resulting quantum theory we
demonstrate the emergence of a particle interpretation, fully consistent with
general relativistic geometry. The path-dependency of parallel transport forces
each observer to carry his own quantum state; we find that the communication of
the corresponding quantum information may generate extra particles on curved
spacetimes. A speculative link between quantum information and spacetime
curvature is discussed which might lead to novel explanations for quantum
decoherence and vanishing interference in double-slit or interaction-free
measurement scenarios, in the mere presence of additional observers.
