  Super-Earths possess low-mass H$_2$/He atmospheres (typically less than 10%
by mass). However, the origins of super-Earth atmospheres have not yet been
ascertained. We investigate the role of rapid disk clearing by photoevaporation
during the formation of super-Earths and their atmospheres. We perform unified
simulations of super-Earth formation and atmospheric evolution in evolving
disks that consider both photoevaporative winds and magnetically driven disk
winds. For the growth mode of planetary cores, we consider two cases in which
planetary embryos grow with and without pebble accretion. Our main findings are
summarized as follows. (i) The time span of atmospheric accretion is shortened
by rapid disk dissipation due to photoevaporation, which prevents super-Earth
cores from accreting massive atmospheres. (ii) Even if planetary cores grow
rapidly by embryo accretion in the case without pebble accretion, the onset of
runaway gas accretion is delayed because the isolation mass for embryo
accretion is small. Together with rapid disk clearing, the accretion of massive
atmospheres can be avoided. (iii) After rapid disk clearing, a number of
high-eccentricity embryos can remain in outer orbits. Thereafter, such embryos
may collide with the super-Earths, leading to efficient impact erosion of
accreted atmospheres. We, therefore, find that super-Earths with low-mass
H$_2$/He atmospheres are naturally produced by N-body simulations that consider
realistic disk evolution.
