Initial state preparation and stability in narrow band-gap semiconductor qubits

Solid state quantum computing has been an area of intense research over the past few years. In most semiconductor implementations, III-V materials have been used in order to exploit their comparatively long mean-free paths and phase coherent times. While most of the attention has been focused on the different possible implementations of gates necessary for computation, little effort has been made to examine the preparation and stability of the initial state of these semiconductor qubits. In this paper, we examine initial state preparation and stability in coupled waveguide qubits formed in several III-V semiconductor hetrostructures. We examine the sensitivity of the initial state to variations in the coupling length between the waveguides, material disorder introduced through mean-free path approximations, and through introduction of phase coherent times.