Experimental hierarchy of the nonclassicality of single-qubit states via potentials for entanglement, steering, and Bell nonlocality

Entanglement potentials are a promising way to quantify the nonclassicalityof single-mode states. They are defined by the amount of entanglement(expressed by, e.g., the Wootters concurrence) obtained after mixing theexamined single-mode state with a purely classical state; such as the vacuum ora coherent state. We generalize the idea of entanglement potentials to otherquantum correlations: the EPR steering and Bell nonlocality, thus enabling usto study mutual hierarchies of these nonclassicality potentials. Instead of theusual vacuum and one-photon superposition states, we experimentally test thisconcept using specially tailored polarization-encoded single-photon states. Onepolarization encodes a given nonclassical single-mode state, while the otherserves as the vacuum place-holder. This technique proves to be experimentallymore convenient in comparison to the vacuum and a one-photon superposition asit does not require the vacuum detection.