Quantum Phase Transition of ${}^3\mathrm{He}$ in Aerogel at a Nonzero Pressure

We present evidence for a nonzero pressure, $T=0\mathrm{}$ superfluid phase transition of ${}^3\mathrm{He}$ in 98.2% open aerogel. Unlike bulk ${}^3\mathrm{He}$ which is a superfluid at $T=0\mathrm{}$ at all pressures (densities) between zero and the melting pressure, ${}^3\mathrm{He}$ in aerogel is not superfluid unless the ${}^3\mathrm{He}$ density exceeds a critical value ${\rho }_c$. About 90% of the ${}^3\mathrm{He}$ added above ${\rho }_c$ contributes to the superfluid density.