Recent developments in space technology like micro-propulsion systems for drag-free control, thermal shielding, ultra-stable laser sources and stable optical cavities set an ideal platform for quantum optomechanical exper- iments with optically trapped dielectric spheres. Here, we will provide an overview of the results of recent studies aiming at the realization of the space mission MAQRO to test the foundations of quantum physics in a parameter regime orders of magnitude beyond existing experiments. In particular, we will discuss DECIDE, which is an experiment to prepare and then study a Schrodinger-cat-type state, where a dielectric nanosphere of around 100 nm radius is prepared in a superposition of being in two clearly distinct positions at the same time. This superposition leads to double-slit-type interference, and the visibility of the interference pattern will be compared to the predictions of quantum theory. This approach allows for testing for possible deviations from quantum theory as our test objects approach macroscopic dimensions. With DECIDE, it will be possible to distinctly test several prominent theoretical models that predict such deviations, for example: the Diósi-Pensrose model, the continuous-spontaneous-localization model of Ghirardi, Rimini, Weber and Pearle, and the model of Károlyházy.
Chirped-pulse interferometry is a new interferometric technique encapsulating the advantages of the quantum
Hong-Ou-Mandel interferometer without the drawbacks of using entangled photons. Both interferometers can
exhibit even-order dispersion cancellation which allows high resolution optical delay measurements even in thick
optical samples. In the present work, we show that finite frequency correlations in chirped-pulse interferometry
and Hong-Ou-Mandel interferometry limit the degree of dispersion cancellation. Our results are important
considerations in designing practical devices based on these technologies.
Quantum physics experiments in space using entangled photons and
satellites are within reach of current technology. We propose a series of fundamental quantum physics experiments that make advantageous use of the space infrastructure with specific emphasis on the satellite-based distribution of entangled photon pairs. The experiments are feasible already today and will eventually lead to a Bell-experiment over thousands of kilometers, thus demonstrating quantum correlations over distances which cannot be achieved by purely earth-bound experiments.