Transition from a polaronic condensate to a degenerate Fermi gas of heteronuclear molecules

The interplay of quantum statistics and interactions in atomic Bose--Fermi mixtures leads to a phase diagram markedly different from pure fermionic or bosonic systems. However, investigating this remains challenging when bosons condense. Here, we observe evidence for transition polaronic molecular density-matched degenerate mixture. condensate fraction, representing the order parameter transition, is depleted by build-up strong correlations results emergence Fermi gas. By driving through ultimately produce quantum-degenerate sample sodium-potassium molecules exhibiting large molecule-frame dipole moment 2.7 Debye. observed represents new phenomenon complementary paradigmatic BEC-BCS crossover