Dimension witnesses and quantum state discrimination

Understand

Dimension witnesses allow one to test the dimension of an unknown physical system in a device-independent manner, that is, without placing assumptions about the functioning of the devices used in the experiment.

• Here we present simple and general dimension witnesses for quantum systems of arbitrary Hilbert space dimension.
• Our approach is deeply connected to the problem of quantum state discrimination, hence establishing a strong link between these two research topics.
• Finally, our dimension witnesses can distinguish between classical and quantum systems of the same dimension, making them potentially useful for quantum information processing.