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arXiv:quant-ph/0007078

Gravitationally induced transition to classical behavior above 10^10 proton masses

Sergio De Filippo

Published Jul 20, 2000• 0 citations
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Abstract

The localization length for the center of mass motion of a matter lump, induced by gravitation, is obtained, without using any phenomenological constants. Its dependence from mass and volume is consistent both with unitary evolution of microscopic particles and with the classical behavior of macroscopic bodies required to account for wave function collapse in quantum measurements, the transition between the two regimes being rather sharp. The gravitational interaction of nonrelativistic matter is modelled by a Yukawa Hamiltonian with vanishing pion mass, no gravitational background is needed and the only hypothesis consists in assuming unentanglement between matter and the Yukawa field.

DOI
10.48550/arxiv.quant-ph/0007078

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The localization length for the center of mass motion of a matter lump, induced by gravitation, is obtained, without using any phenomenological constants. Its dependence from mass and volume is consistent both with unitary evolution of microscopic particles and with the classical behavior of macroscopic bodies required to account for wave function collapse in quantum measurements, the transition between the two regimes being rather sharp. The gravitational interaction of nonrelativistic matter is modelled by a Yukawa Hamiltonian with vanishing pion mass, no gravitational background is needed and the only hypothesis consists in assuming unentanglement between matter and the Yukawa field.
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What if gravity is classical? If true, a consistent coexistence of classical gravity and quantum matter requires that gravity exhibit irreducible fluctuations. These fluctuations can mediate classical correlations, but not quantum entanglement, between the quantized motion of the gravitationally interacting matter. We use a consistent theory of quantum-classical dynamics in the Newtonian limit of gravity to show that experimentally relevant observables can conclusively test the hypothesis that gravity is classical. This can be done, for example, by letting highly coherent source masses interact with each other gravitationally, and performing precise measurements of the cross-correlation of their motion. Theory predicts a characteristic phase response that distinguishes classical gravity from quantum gravity, and from naive sources of decoherence. Such experiments are imminently viable.