  Recent observation of diminishing superfluid phase stiffness upon increasing
carrier density in cuprate high-temperature superconductors is unexpected from
the quantum density-phase conjugation of superfluidity. Here, through analytic
estimation and verified via variational Monte Carlo calculation of an emergent
Bose liquid, we point out that Mottness of the underlying carriers can cause a
stronger phase fluctuation of the superfluid with increasing carrier density.
This effect turns the expected density-increased phase stiffness into a dome
shape, in good agreement with the recent observation. Specifically, the
effective mass divergence due to "jamming" of the low-energy bosons reproduces
the observed nonlinear relation between phase stiffness and transition
temperature. Our results suggest a new paradigm, in which unconventional
superconductivity in some strongly correlated materials is described by physics
of bosonic superfluidity, as opposed to pairing-strength limited Cooper
pairing.
