  With a large portfolio of elemental quantum components, superconducting
quantum circuits have contributed to dramatic advances in microwave quantum
optics. Of these elements, quantum-limited parametric amplifiers have proven to
be essential for low noise readout of quantum systems whose energy range is
intrinsically low (tens of $\mu$eV ). They are also used to generate non
classical states of light that can be a resource for quantum enhanced
detection. Superconducting parametric amplifiers, like quantum bits, typically
utilize a Josephson junction as a source of magnetically tunable and
dissipation-free nonlinearity. In recent years, efforts have been made to
introduce semiconductor weak links as electrically tunable nonlinear elements,
with demonstrations of microwave resonators and quantum bits using
semiconductor nanowires, a two dimensional electron gas, carbon nanotubes and
graphene. However, given the challenge of balancing nonlinearity, dissipation,
participation, and energy scale, parametric amplifiers have not yet been
implemented with a semiconductor weak link. Here we demonstrate a parametric
amplifier leveraging a graphene Josephson junction and show that its working
frequency is widely tunable with a gate voltage. We report gain exceeding 20 dB
and noise performance close to the standard quantum limit. Our results complete
the toolset for electrically tunable superconducting quantum circuits and offer
new opportunities for the development of quantum technologies such as quantum
computing, quantum sensing and fundamental science.
