Landau–Zener transitions in coupled qubits: Effects of coloured noise

Abstract

Abstract The feasibility of stochastic Hamiltonians for interacting qubits to deliver consistent quantum speedups in quantum adiabatic optimisation remains an open question. This paper studies theoretically the noisy Landau–Zener model of a system of two interacting qubits. Exact analytic results are obtained for all transition probabilities via nonstationary perturbation technique, even where semiclassical trajectories interfere. Where the system is driven by slow classical Gaussian noise, destructive interference of the trajectories results in forbidden transitions. However, in the fast noise regime, these transitions have non-zero probabilities. We elucidate the roles of noise parameters on the decoherence of coupled qubits.