Reflectors for experimental set-ups in the laboratory.
Quantum mechanics is based on certain postulates, such as Born’s rule, which states that the probability density is given by the absolute square of the wavefunction. While it is impossible to proof this without making other assumptions on the mathematical structure of the measurement process, one can make interferometric experiments and check if the results follow the distribution predicted by Born’s rule. A consequence of any deviation would be higher-order interference in multi-path interferometers.
We have shown that a fundamental quantum advantage is possible when using true single photons instead of coherent states produced by a laser in interferometers. This allowed us to increase the sensitivity and find a tight upper bound to any potential deviation. Now we are increasing the phase stability of our interferometer and use more complex multi-path interferometers to further enhance the sensitivity of our experiments.