  We report on the creation of bosonic NaCs molecules in their absolute
rovibrational ground state via stimulated Raman adiabatic passage. We create
ultracold gases with up to 22,000 dipolar NaCs molecules at a temperature of
300(50) nK and a peak density of $1.0(4) \times 10^{12}$ cm$^{-3}$. We
demonstrate comprehensive quantum state control by preparing the molecules in a
specific electronic, vibrational, rotational, and hyperfine state. Employing
the tunability and strength of the permanent electric dipole moment of NaCs, we
induce dipole moments of up to 2.6 D. Dipolar systems of NaCs molecules are
uniquely suited to explore strongly interacting phases in dipolar quantum
matter.
