  Blurring the boundary between bosons and fermions lies at the heart of a wide
range of intriguing quantum phenomena in multiple disciplines, ranging from
condensed matter physics and atomic, molecular and optical physics to high
energy physics. One such example is a multi-component Fermi gas with SU($N$)
symmetry that is expected to behave like spinless bosons in the large $N$
limit, where the large number of internal states weakens constraints from the
Pauli exclusion principle. However, bosonization in SU($N$) fermions has never
been established in high dimensions where exact solutions are absent. Here, we
report direct evidence for bosonization in a SU($N$) fermionic ytterbium gas
with tunable $N$ in three dimensions (3D). We measure contacts, the central
quantity controlling dilute quantum gases, from the momentum distribution, and
find that the contact per spin approaches a constant with a 1/$N$ scaling in
the low fugacity regime consistent with our theoretical prediction. This
scaling signifies the vanishing role of the fermionic statistics in
thermodynamics, and allows us to verify bosonization through measuring a single
physical quantity. Our work delivers a highly controllable quantum simulator to
exchange the bosonic and fermionic statistics through tuning the internal
degrees of freedom in any generic dimensions. It also suggests a new route
towards exploring multi-component quantum systems and their underlying
symmetries with contacts.
