  Critical phenomena of quantum systems are useful for enhancement of quantum
sensing. However, experimental realizations of criticality enhancement have
been confined to very few systems, owing to the stringent requirements,
including the thermodynamical or scaling limit, and fine control of interacting
quantum susystems or particles. We here propose a simple critical quantum
sensing scheme that requires neither of these conditions. The critical system
is realized with a single parametrically-driven bosonic mode involving many
non-interacting bosons. We calculate the quantum Fisher information, and
perform a simulation, which confirms the criticality-enabled enhancement. We
further detail the response of one of the quadratures to the variation of the
control parameter. The numerical results reveal that its inverted variance
exhibits a diverging behavior at the critical point. Based on the presently
available control techniques of parametric driving, we expect our scheme can be
realized in different systems, e.g., ion traps and superconducting circuits.
