Community Research and Development Information Service - CORDIS


MassQ Report Summary

Project ID: 339897
Funded under: FP7-IDEAS-ERC
Country: Germany

Mid-Term Report Summary - MASSQ (Massive-Object Quantum Physics)

The world of quantum physics is usually associated with the microscopic cosmos of atoms and photons. In principle, but so far without any demonstration, even heavy objects can exhibit the distinguished properties of quantum world particles. In 1935, Einstein, Podolsky and Rosen (EPR) challenged a particular prediction of quantum theory saying that two particles can exist in a so-called entangled state in which the two particles do not have individually defined (‘local’) positions and momenta. Most interestingly, the existence of entangled states was subsequently fully confirmed in experiments with photons and atoms.
The ERC project ‘MassQ’ aims to test and to confirm quantum theory in the macroscopic world of massive, human-world sized objects by realizing an EPR entanglement experiment with heavy mirrors. Two kg-sized mirrors will be cooled to low temperature and their centre of mass motion driven by radiation pressure of intense laser light in such a way that the mirrors will lose their individually defined positions and momenta. As a result, their joint motion will form a unified massive quantum object.
The goal of this project is a fundamental test of quantum theory in the so far unexplored regime of human-world sized objects. Recent advances in gravitational wave detector research and in opto-mechanics make this project feasible. The vision of this project points even further into the future. This project aims to lay the basis for a completely new class of physics experiments. Mirrors with kilogram masses have a proper gravitational field and cause a space-time curvature in their vicinity. This way, in principle, the dynamics of two heavy entangled mirrors need to be described not only by quantum theory but also by general relativity. Today it is completely unclear what the results of such a new class of physics experiments will be. Undoubtedly, they are important to illuminate the deep connection between the two most successful theories in physics.

The idea behind MassQ is to prepare two super-polished laser mirrors that are suspended as pendulums in a very cold and silent environment, to shine two laser beams onto these mirrors, and to photo-electrically detect the interference products of these laser beams. If the quantum uncertainty of the laser beams’ radiation pressure influences the motion of the mirrors stronger than any remaining coupling to the environment, light and mirror motion gets entangled. By detecting the laser beams’ interference product the entanglement is swapped to entanglement of the motion of the two mirrors. Laser light will also used to verify the entanglement of the two mirrors by observing the EPR paradox.
So far, MassQ has developed a new laser interferometer type, which efficiently allows for the generation and verification of the entanglement. First experimental tests on the laser interferometer type were successful when using a 1mm2-sized membrane mirror instead of a massive mirror. The experiment confirmed that the new interferometer type is able to generate entanglement between two mirrors. Our work provides new fundamental insight in optomechanical coupling between light and mirror motion. For the first time, generalized optomechanical coupling was observed where the out-coupled information about the mirror motion was collected by a photo-diode. Generalized optomechanical coupling simultaneously uses two distinct coupling mechanisms and are in particular useful to produce entanglement of heavy mirrors. The successful test of the new laser interferometer type has been crucial for the realization of entangled motion of two heavy mirrors, which is the goal of the remaining two and a half years of MassQ.

Reported by

Follow us on: RSS Facebook Twitter YouTube Managed by the EU Publications Office Top