  We propose Gaussian quantum illumination(QI) protocol exploiting
asymmetrically squeezed two-mode(ASTM) state that is generated by applying
single-mode squeezing operations on each mode of an initial two-mode squeezed
vacuum(TMSV) state, in order to overcome the limited brightness of a TMSV
state. We show that the performance of the optimal receiver is enhanced by
local squeezing operation on a signal mode whereas the performance of a
realistic receiver can be enhanced by local squeezing operations on both input
modes. Under a fixed mean photon number of the signal mode, the ASTM state can
be close to the TMSV state in the performance of QI while there is a threshold
of beating classical illumination in the mean photon number of the initial TMSV
state. We also verify that quantum discord cannot be a resource of quantum
advantage in the Gaussian QI using the ASTM state, which is a counterexample of
a previous claim.
