A monocycle entangled photon pair is a two-photon state that has a temporal quantum correlation within an optical cycle (~3.6 fs). By making use of such correlation in ultrafast time scale, one can expect several applications to quantum metrology including sub-micron quantum optical coherence tomography. In this presentation we introduce the generation of ultra-broadband near-infrared photon pairs from MgSLT crystal with chirped poling period and the observation of frequency correlation. We also discuss the possibility of compressing photon pairs in monocycle time scale.