  We study particle and spin transport in a single mode quantum point contact
using a charge neutral, quantum degenerate Fermi gas with tunable, attractive
interactions. This yields the spin and particle conductance of the point
contact as a function of chemical potential or confinement. The measurements
cover a regime from weak attraction, where quantized conductance is observed,
to the resonantly interacting superfluid. Spin conductance exhibits a broad
maximum when varying the chemical potential at moderate interactions, which
signals the emergence of Cooper pairing. In contrast, the particle conductance
is unexpectedly enhanced even before the gas is expected to turn into a
superfluid, continuously rising from the plateau at 1/h for weak interactions
to plateaux-like features at non-universal values as high as 4/h for
intermediate interactions. For strong interactions, the particle conductance
plateaux disappear and the spin conductance gets suppressed, confirming the
spin-insulating character of a superfluid. Our observations document the
breakdown of universal conductance quantization as many-body correlations
appear. The observed anomalous quantization challenges a Fermi liquid
description of the normal phase, shedding new light on the nature of the
strongly attractive Fermi gases.
