  The quasi-stellar object (QSO)/merger Mrk 231 is arguably the nearest and
best laboratory for studying QSO feedback. It hosts several outflows, including
broad-line winds, radio jets, and a poorly-understood kpc scale outflow. In
this Letter, we present integral field spectroscopy from the Gemini telescope
that represents the first unambiguous detection of a wide-angle, kpc scale
outflow from a powerful QSO. Using neutral gas absorption, we show that the
nuclear region hosts an outflow with blueshifted velocities reaching 1100 km/s,
extending 2-3 kpc from the nucleus in all directions in the plane of the sky. A
radio jet impacts the outflow north of the nucleus, accelerating it to even
higher velocities (up to 1400 km/s). Finally, 3.5 kpc south of the nucleus,
star formation is simultaneously powering an outflow that reaches more modest
velocities of only 570 km/s. Blueshifted ionized gas is also detected around
the nucleus at lower velocities and smaller scales. The mass and energy flux
from the outflow are >~2.5 times the star formation rate and >~0.7% of the
active galactic nucleus luminosity, consistent with negative feedback models of
QSOs.
