Newtonian Gravity Produces Quantum Entanglement Via Two-Qubit Interaction, Demonstrating Non-Local Coupling

The fundamental connection between gravity and quantum mechanics remains one of the most challenging problems in physics, and researchers continually seek ways to bridge these seemingly disparate realms. Feng-Li Lin of National Taiwan Normal University and Sayid Mondal of Universidad Arturo Prat, along with their colleagues, now demonstrate that even Newtonian gravity, the classical description of gravitational force, can generate quantum entanglement between objects. This achievement establishes a framework for understanding how classical gravity influences quantum phenomena, revealing that entanglement arises from the way objects interact gravitationally through a non-local coupling. The discovery offers a novel perspective on the interplay between gravity and quantum mechanics, potentially paving the way for exploring quantum gravity effects in macroscopic systems.

Gravity Entangles Quantum Bodies via Superposition

Scientists have demonstrated that Newtonian gravity can induce quantum entanglement between two distant bodies, a result achieved through a novel combination of classical gravity and quantum superposition. The research centers on preparing “quantum bodies”, objects in a superposition of two mass distributions, and examining their interaction via gravity. These quantum bodies are created using N00N states, which distribute quantum properties across spatial locations, effectively creating a qubit representing the object’s mass configuration. The team derived an effective field theory describing the interaction, revealing a two-qubit interaction governed by a Newtonian, nonlocal quadrupole-quadrupole coupling.

This interaction, stemming from the gravitational force between the mass distributions, produces entanglement, as evidenced by a non-zero entanglement entropy in the final state after the system evolves. Measurements confirm that the entanglement is governed by a coupling constant that is nonlocal, meaning the interaction doesn’t diminish with distance as expected in classical physics. The team calculated the entanglement generated, finding it scales with the gravitational coupling constant, the mass fluctuations, the interaction time, and is inversely proportional to both the distance between the bodies and their size. The calculations demonstrate that the entanglement strength is approximately proportional to GδM1δM2 r12 -4 T, where G is the gravitational constant, δM1 and δM2 represent the mass fluctuations, r12 is the distance between the bodies, and T is the interaction time.

This work establishes a direct link between Newtonian gravity and quantum entanglement, suggesting that even classical gravity can generate quantum correlations under specific conditions. Importantly, the team identified specific parameter values, termed “magic points”, where entanglement production vanishes entirely, suggesting a nuanced relationship between gravitational interaction and quantum coherence. While acknowledging the limitations of restricting calculations to Newtonian order, the authors suggest that incorporating higher-order post-Newtonian interactions could further refine the understanding of entanglement production. Future research may focus on exploring the physical implications of these “magic points” and investigating the role of higher-order interactions in mediating quantum entanglement through classical gravity.