Spatial decoherence due to non-inertial motion

We show that an accelerating, spatially-superposed particle interacting with the Minkowski vacuum exhibits decoherence in the position basis. Such spatial decoherence arises, to leading order, from two mechanisms: (1) coupling of the particle’s internal degree with the transformed field state seen in the proper frame, and (2) time dilation across the spatial extent of the superposition [1]. In the case of uniform acceleration, it is well-known that the particle observes a thermal field at the Davies-Unruh temperature $T_{DU}$ [2,3]—we demonstrate that the backaction of such a field leads to a spatial decoherence consistent with that of an inertial particle immersed in a thermal field at $T_{DU}$. For stationary worldlines other than uniform acceleration (e.g., circular motion), the particle perceives the Minkowski vacuum as a colored noise [4] and experiences a concomitant rate of decoherence. Since the particle’s trajectory determines the apparent correlations created between the otherwise uncorrelated vacuum field modes, the rate of decoherence is determined by the choice of trajectory. In this sense, spacetime behaves as an observer-specific thermodynamic reservoir which induces decoherence consequent to the worldline.

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