  The interpretation of measurements of high-energy particle collisions relies
heavily on the performance of full event generators. By far the largest amount
of time to predict the kinematics of multi-particle final states is dedicated
to the calculation of the hard process and the subsequent parton shower step.
With the continuous improvement of quantum devices, dedicated algorithms are
needed to exploit the potential quantum computers can provide. We propose
general and extendable algorithms for quantum gate computers to facilitate
calculations of helicity amplitudes and the parton shower process. The helicity
amplitude calculation exploits the equivalence between spinors and qubits and
the unique features of a quantum computer to compute the helicities of each
particle involved simultaneously, thus fully utilising the quantum nature of
the computation. This advantage over classical computers is further exploited
by the simultaneous computation of s and t-channel amplitudes for a
2$\rightarrow$2 process. The parton shower algorithm simulates collinear
emission for a two-step, discrete parton shower. In contrast to classical
implementations, the quantum algorithm constructs a wavefunction with a
superposition of all shower histories for the whole parton shower process, thus
removing the need to explicitly keep track of individual shower histories. Both
algorithms utilise the quantum computer's ability to remain in a quantum state
throughout the computation and represent a first step towards a quantum
computing algorithm to describe the full collision event at the LHC.
