We study adiabatic population transfer between discrete positions. Being closely related to stimulated Raman adiabatic passage in optical systems, this transport is coherent and robust against variations of experimental parameters. Thanks to these properties the scheme is a promising candidate for transport of quantum information in quantum computing. We study the effects of spatially registered noise sources on the quantum transport and in particular model Markovian decoherence via nonlocal coupling to nearby quantum point contacts which serve as information readouts. We find that the rate of decoherence experienced by a spatial superposition initially grows with spatial separation but surprisingly then plateaus. In addition we include non-Markovian effects due to couplings to nearby two-level systems and we find that although the population transport exhibits robustness in the presence of both types of noise sources, the transport of a spatial superposition exhibits severe fragility.
Kamleitner I, Cresser J and Twamley J, Phys. Rev. A, 77(3) 032331, March 2008. Copyright 2008 by the American Physical Society. The original article can be found at http://link.aps.org/doi/10.1103/PhysRevA.77.032331.