  We propose a theoretical scheme to realize a sensitive amplification of
quantum discord (QD) between two atomic qubits via a cavity-Bose-Einstein
condensate (BEC) system which was used to firstly realize the Dicke quantum
phase transition (QPT) [Nature 464, 1301 (2010)]. It is shown that the
influence of the cavity-BEC system upon the two qubits is equivalent to a phase
decoherence environment. It is found that QPT in the cavity-BEC system is the
physical mechanism of the sensitive QD amplification.
