  Understanding the origins of unconventional superconductivity has been a
major focus of condensed matter physics for many decades. While many questions
remain unanswered, experiments have found that the systems with the highest
critical temperatures tend to be layered materials where superconductivity
occurs in two-dimensional (2D) structures. However, to what extent the
remarkable stability of these strongly correlated 2D superfluids is related to
their reduced dimensionality is still an open question. In this work, we use
dilute gases of ultracold fermionic atoms as a model system to directly observe
the influence of dimensionality on strongly interacting fermionic superfluids.
We achieve this by measuring the superfluid gap of a strongly correlated
quasi-2D Fermi gas over a wide range of interaction strengths and comparing the
results to recent measurements in 3D Fermi gases. We find that the superfluid
gap follows the same universal function of the interaction strength in both
systems, which suggests that there is no inherent difference in the stability
of fermionic superfluidity between two- and three-dimensional quantum gases.
Finally, we compare our data to results from solid state systems and find a
similar relation between the interaction strength and the gap for a wide range
of two- and three-dimensional superconductors.
