  Quarks and gluons are the fundamental building blocks of matter responsible
for most of the visible energy density in the universe. However, they cannot be
directly observed due to the confining nature of the strong force. The LHC uses
pp collisions to probe the highest energy reactions involving quarks and gluons
happening at the smallest distance scales ever studied in a terrestrial
laboratory. The quantum properties of the initiating partons are encoded in the
distribution of energy inside and around jets. These quantum properties of jets
(QPJ) can be used to study the high energy nature of the strong force and
provide a way to tag the hadronic decays of heavy boosted particles. The ATLAS
detector is well-suited to perform measurements of the structure of high energy
jets. A variety of novel techniques utilizing the unique capabilities of the
ATLAS calorimeter and tracking detectors are introduced in order to probe the
experimental and theoretical limits of the QPJ.
  Quarks and gluons may also be the key to understanding fundamental problems
with the SM. In particular, the top quark has a unique relationship with the
newly discovered Higgs boson and as such could be a portal to discovering new
particles. In many extensions of the SM, the top quark has a partner with
similar properties. For example, a SUSY stop could solve The Hierarchy Problem.
Miraculously, a SUSY neutralino could also account for the DM observed in the
universe and may be copiously produced in stop decays. High-energy top quarks
from stops result in jets with a rich structure that can be identified using
the techniques developed in the study of the QPJ. While there is no significant
evidence for stop production at the LHC, the stringent limits established by
this search have important implications for SUSY and other models.
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