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Quantum gravitational contrast in creating Schrödinger cat state

Anupam Mazumdar and Tian Zhou*

  • *Contact author: t.zhou@rug.nl
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Phys. Rev. D 114, 104025 – Published 6 November, 2026

DOI: https://doi.org/10.1103/dkq1-kbs5

Abstract

In this paper, we illustrate how a Schrödinger cat state created via a matter-wave interferometer can be viewed as the simplest quantum-gravity setup where we can treat both matter and gravity on an equal footing at a perturbative level. Here, we treat Einstein’s theory of general relativity using an effective field theory approach, quantizing the massless spin-2 graviton in the presence of a quantum spatial superposition of matter that creates a matter-wave interferometer in the nonrelativistic limit. We show that, due to the matter-graviton coupling, the graviton vacuum is displaced analogous to the coherent state. We study the contrast/overlap between the coherent states of the left and right superpositions in the matter-wave interferometer. We also study the entanglement between matter and the graviton in this setup and relate it to a gravitational contrast, or the overlap of the quantum geometries led by the coherent states. In Appendix B, we provide an example of a time-dependent harmonic oscillator and study the contrast/overlap of such coherent states of the graviton.

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Phys. Rev. D 114, 104025– Published 6 November, 2026
  • Received 4 June 2026
  • Accepted 16 October 2026
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