  Proximity effect is a very powerful approach and has been widely applied to
induce electron correlations such as: superconductivity, magnetism and
spin-orbit effects at the interface of heterostructure quantum materials.
However, proximity induced charge density wave (CDW) state has remained
elusive. We report the first observation of a novel proximity induced CDW
within a graphene layer that is deposited on 1T-TaS2 crystal. By using scanning
tunneling microscopy and spectroscopy to probe the interface of the
graphene/1T-TaS2 heterostructure together with theoretical modeling, we show
that the interactions between the Dirac-like carriers in graphene and the
correlated electrons in 1T-TaS2 induce a periodic charge density modulation
within graphene and modify the band structure at the surface of 1T-TaS2,
resulting in a 7.5% reduction of its gap size. Our results provide a new
platform to manipulate the electron charge correlations in heterostructures.
