Macroscopic quantum resonators (MAQRO)

Abstract

Quantum physics challenges our understanding of the nature of physical reality and of space-time and suggests the necessity of radical revisions of their underlying concepts. Experimental tests of quantum phenomena involving massive macroscopic objects would provide novel insights into these fundamental questions. Making use of the unique environment provided by space, MAQRO aims at investigating this largely unexplored realm of macroscopic quantum physics. MAQRO has originally been proposed as a medium-sized fundamental-science space mission for the 2010 call of Cosmic Vision. MAQRO unites two experiments: DECIDE (DECoherence In Double-Slit Experiments) and CASE (Comparative Acceleration Sensing Experiment). The main scientific objective of MAQRO, which is addressed by the experiment DECIDE, is to test the predictions of quantum theory for quantum superpositions of macroscopic objects containing more than 10 8 atoms. Under these conditions, deviations due to various suggested alternative models to quantum theory would become visible. These models have been suggested to harmonize the paradoxical quantum phenomena both with the classical macroscopic world and with our notion of Minkowski space-time. second scientific objective of MAQRO, which is addressed by the experiment CASE, is to demonstrate the performance of a novel type of inertial sensor based on optically trapped microspheres. CASE is a technology demonstrator that shows how the modular design of DECIDE allows to easily incorporate it with other missions that have compatible requirements in terms of spacecraft and orbit. CASE can, at the same time, serve as a test bench for the weak equivalence principle, i.e., the universality of free fall with test-masses differing in their mass by 7 orders of magnitude.

Macroscopic quantum mechanics: theory and experimental concepts of optomechanics

“…[261], Romero-Isart discussed more types of decoherence models that are motivated by the interplay between gravity and quantum mechanics, and outlined an ambitious research program not using nearly Gaussian states, but states that have wavefunction spread comparable to or bigger than the physical size of the mechanical objects. These experiments are intended to be performed in space, where decoherence from a suspension system will no longer be an issue [262].…”

Optomechanical Schrödinger cats – a case for space

“…We consider a situation in which we can cool the center-of-mass of a nano-or microsphere close to its quantum ground state of motion (see [51] for more details on the experimental requirements). After successful cooling, the particle will be released and its wave-packet will expand rapidly.…”

“…We have analyzed the technical requirements for a space-based configuration of this type in detail in two recent studies [51,57] and we refer the reader to these documents for more technical details.…”

“…According to quantum theory, a successful preparation of such a state will result in an interference pattern similar to the one occurring in the well-known double-slit experiment. Experiments of this type have been proposed both for ground-based experiments [59,60] as well as for experiments in a space environment [51,57]. In a space environment, such experiments could allow for testing quantum theory over a vastly larger parameter range than WAX [51,57] -hopefully resulting in increasingly "burlesque" situations of superpositions of macroscopically distinct states.…”

“…Experiments of this type have been proposed both for ground-based experiments [59,60] as well as for experiments in a space environment [51,57]. In a space environment, such experiments could allow for testing quantum theory over a vastly larger parameter range than WAX [51,57] -hopefully resulting in increasingly "burlesque" situations of superpositions of macroscopically distinct states. Ultimately, one should attempt to increase the mass of the particle to a regime, where its own gravitational field can no longer be neglected.…”