  Ensembles of particles governed by quantum mechanical laws exhibit
fascinating emergent behavior. Atomic quantum gases, liquid helium, and
electrons in quantum materials all show distinct properties due to their
composition and interactions. Quantum degenerate samples of bosonic dipolar
molecules promise the realization of novel phases of matter with tunable
dipolar interactions and new avenues for quantum simulation and quantum
computation. However, rapid losses, even when reduced through collisional
shielding techniques, have so far prevented cooling to a Bose-Einstein
condensate (BEC). In this work, we report on the realization of a BEC of
dipolar molecules. By strongly suppressing two- and three-body losses via
enhanced collisional shielding, we evaporatively cool sodium-cesium (NaCs)
molecules to quantum degeneracy. The BEC reveals itself via a bimodal
distribution and a phase-space-density exceeding one. BECs with a condensate
fraction of 60(10) % and a temperature of 6(2) nK are created and found to be
stable with a lifetime close to 2 seconds. This work opens the door to the
exploration of dipolar quantum matter in regimes that have been inaccessible so
far, promising the creation of exotic dipolar droplets, self-organized crystal
phases, and dipolar spin liquids in optical lattices.
