We numerically study the evolution of an adiabatic quantum computer in the presence of a Markovian ohmic environment. We consider Ising spin glass systems with up to 20 coupled qubits that are independently coupled to the environment via two conjugate degrees of freedom. We demonstrate that the required computation time in the presence of the environment is of the same order as that for an isolated system, and is not limited by the single qubit decoherence time T2*, even when the minimum gap is much smaller than temperature. We also show that the behavior of the system can be efficiently described by a two-state model with only longitudinal coupling to the environment.
The main result is summarized in the conclusions:
…we have explicitly demonstrated that the computation time in AQC can be much longer than single qubit decoherence time T2∗.