Fragility of quantum correlations and coherence in a multipartite photonic system

Certain quantum states are well known to be particularly fragile in the presence of decoherence, as illustrated by Schrodinger's famous gedanken cat experiment. More recently it has been considered that quantum states can be characterized through a hierarchy of quantum quantities such as entanglement, quantum correlations, and quantum coherence. It has been conjectured that each of these quantities has various degrees of fragility in the presence of decoherence. Here we experimentally confirm this conjecture by preparing tripartite photonic states and subjecting them to controlled amounts of dephasing. When the dephasing is applied to all the qubits, we find that the entanglement is the most fragile quantity, followed by the quantum coherence and then mutual information. This is in agreement with the widely held expectation that multipartite quantum correlations are a highly fragile manifestation of quantumness. We also perform dephasing on one of the three qubits on star and WW states. Here the distribution of the correlations and coherence in the star state becomes more important in relation to the dephasing location.