Scaling Considerations in Ground State Quantum Computation

We study design challenges associated with realizing a ground state quantum computer. In such a computer, the energy gap between the ground state and first excited state must be sufficiently large to prevent disruptive excitations. Here, an estimate is provided of this gap as a function of computer size. We then address the problem of detecting the output of a ground state quantum computer. It is shown that the exponential detection difficulties that appear to be present at first can be overcome in a straightforward manner by small design changes.