title: Macroscopic quantum mechanics in a classical spacetime.
abstract: We apply the many-particle Schrödinger-Newton equation, which describes the coevolution of a many-particle quantum wave function and a classical space-time geometry, to macroscopic mechanical objects. By averaging over motions of the objects' internal degrees of freedom, we obtain an effective Schrödinger-Newton equation for their centers of mass, which can be monitored and manipulated at quantum levels by state-of-the-art optomechanics experiments. For a single macroscopic object moving quantum mechanically within a harmonic potential well, its quantum uncertainty is found to evolve at a frequency different from its classical eigenfrequency-with a difference that depends on the internal structure of the object-and can be observable using current technology. For several objects, the Schrödinger-Newton equation predicts semiclassical motions just like Newtonian physics, yet quantum uncertainty cannot be transferred from one object to another.
authors.affiliation: Theoretical Astrophysics 350-17, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Huan
authors.initials: H
authors.lastname: Yang
authors.forename: Haixing
authors.initials: H
authors.lastname: Miao
authors.forename: Da-Shin
authors.initials: DS
authors.lastname: Lee
authors.forename: Bassam
authors.initials: B
authors.lastname: Helou
authors.forename: Yanbei
authors.initials: Y
authors.lastname: Chen