  The velocity of alpha particles relative to protons can vary depending on the
solar wind type and distance from the Sun (Marsch 2012). Measurements from the
previous spacecraft provided the alpha-proton's differential velocities down to
0.3 au. Parker Solar Probe (PSP) now enables insights into differential flows
of newly accelerated solar wind closer to the Sun for the first time. Here, we
study the difference between proton and alpha bulk velocities near PSP
perihelia of Encounters 3-7 when the core solar wind is in the field of view of
the Solar Probe Analyzer for Ions (SPAN-I) instrument. As previously reported
at larger heliospheric distances, the alpha-proton differential speed observed
by PSP is greater for fast wind than the slow solar wind. We compare PSP
observations with various spacecraft measurements and present the radial and
temporal evolution of the alpha-proton differential speed. The differential
flow decreases as the solar wind propagates from the Sun, consistent with
previous observations. While Helios showed a small radial dependence of
differential flow for the slow solar wind, PSP clearly showed this dependency
for the young slow solar wind down to 0.09 au. Our analysis shows that the
alpha-proton differential speed's magnitude is mainly below the local Alfv\'en
speed. Moreover, alpha particles usually move faster than protons close to the
Sun. PSP crossed the Alfv\'en surface during its eighth Encounter and may cross
it in future Encounters, enabling us to investigate the differential flow very
close to the solar wind acceleration source region for the first time.
