  There is a recent surge of interest in amplification and detection of tiny
motion in the growing field of opto and electro mechanics. Here, we demonstrate
widely tunable, broad bandwidth and high gain all-mechanical motion amplifiers
based on graphene/Silicon Nitride (SiNx) hybrids. In these devices, a tiny
motion of a large-area SiNx membrane is transduced to a much larger motion in a
graphene drum resonator coupled to SiNx. Furthermore, the thermal noise of
graphene is reduced (squeezed) through parametric tension modulation. The
parameters of the amplifier are measured by photothermally actuating SiNx and
interferometrically detecting graphene displacement. We obtain displacement
power gain of 38 dB and demonstrate 4.7 dB of squeezing resulting in a
detection sensitivity of 3.8 fm per square root Hz, close to the thermal noise
limit of SiNx.
