Higher entanglement and fidelity with a uniformly accelerated partner   via non-orthogonal states
  We show that nonorthogonal states achieve a higher level of entanglement when one party undergoes uniform acceleration. We also show that in this regime non-orthogonal states achieve a higher fidelity for teleportation. A quantum field as observed by an observer confined to a Rindler wedge acts as an open system. When one traces over the field modes in the causally disconnected region of space time, one finds that, for a qubit derived from the modes of a scalar field, the effective state space of a qubit is deformed. In order to show this we numerically calculate the Bures angle between states as seen by an accelerating observer. We also derive the Bures metric of an effective qubit in the limit of low accelerations. In order to show that the deformation is not just a coordinate transform, we calculate the scalar curvature of the effective Bures metric. We see that the effective Bures metric loses its isotropic nature. Despite taking the limit of low accelerations, our results are also relevant to large gravitational fields. 
G. A. White
quant-ph