It is well known that many operations in quantum information processing depend largely on a special kind of quantum correlation, that is, entanglement. However, quantum correlation can also display the quantum advantage without entanglement. But it is very vulnerable to environmental destruction. Dr.Chuanfeng Li research group of CAS Key Lab of Quantum Information used various Bell-diagonal states as input state under decoherence environment to study the evolution of correlations.
They have shown the sudden change in behaviour in the decay rates of different kinds of correlations in the two-photon system. Their results show that classical and quantum correlations can remain unaffected under certain decoherence areas, which is useful in distinguishing correlations and designing robust quantum protocols based only on quantum correlation.
Moreover, they verified sudden change of quantum and classical correlations under certain decoherence areas, and also show that quantum correlation is larger than classical correlation during the dynamics of a special input state, which disproves the early conjecture that classical correlation is always greater than quantum correlation. This observation will have important roles in quantum research and its application.