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Published August 26, 2016 | Published
Journal Article Open

Universal Decoherence under Gravity: A Perspective through the Equivalence Principle


Pikovski et al. [Nat. Phys. 11, 668 (2015)] show that a composite particle prepared in a pure initial quantum state and propagated in a uniform gravitational field undergoes a decoherence process at a rate determined by the gravitational acceleration. By assuming Einstein's equivalence principle to be valid, we analyze a physical realization of the (1+1)D thought experiment of Pikovski et al. to demonstrate that the dephasing between the different internal states arises not from gravity but rather from differences in their rest mass, and the mass dependence of the de Broglie wave's dispersion relation. We provide an alternative view to the situation considered by Pikovski et al., where we propose that gravity plays a kinematic role by providing a relative velocity to the detector frame with respect to the particle; visibility can be easily recovered by giving the screen an appropriate uniform velocity. We then apply this insight to their thought experiment in (1+1)D to draw a direct correspondence, and obtain the same mathematical result for dephasing. We finally propose that dephasing due to gravity may in fact take place for certain modifications to the gravitational potential where the equivalence principle is violated.

Additional Information

© 2016 American Physical Society. Received 28 March 2016; published 24 August 2016. Y. C. and B. P. are supported by the Institute for Quantum Information and Matter, as well as NSF Grants No. PHY-1404569 and No. PHY-1506453. F. K. was supported by the LIGO NSF Grant No. PHY-1305863 and the Russian Foundation for Basic Research Grant No. 14-02-00399. We thank C. Brukner, I. Pikovski, Y. Ma, B. L. Hu, and O. Romero-Isart for exciting discussions.

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Published - PhysRevLett.117.090401.pdf


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August 20, 2023
August 20, 2023