  Quantum correlations can be stronger than anything achieved by classical
systems, yet they are not reaching the limit imposed by relativity. The
principle of information causality offers a possible explanation for why the
world is quantum and why there appear to be no even stronger correlations.
Generalizing the no-signaling condition it suggests that the amount of
accessible information must not be larger than the amount of transmitted
information. Here we study this principle experimentally in the classical,
quantum and post-quantum regimes. We simulate correlations that are stronger
than allowed by quantum mechanics by exploiting the effect of
polarization-dependent loss in a photonic Bell-test experiment. Our method also
applies to other fundamental principles and our results highlight the special
importance of anisotropic regions of the no-signalling polytope in the study of
fundamental principles.
