Temperature Can Enhance Coherent Oscillations at a Landau-Zener Transition

Robert S. Whitney, Maxime Clusel, Timothy Ziman
2011 Physical Review Letters  
We consider sweeping a system through a Landau-Zener avoided-crossing, when that system is also coupled to an environment or noise. Unsurprisingly, we find that decoherence suppresses the coherent oscillations of quantum superpositions of system states, as superpositions decohere into mixed states. However, we also find an effect we call "Lamb-assisted coherent oscillations", in which a Lamb shift exponentially enhances the coherent oscillation amplitude. This dominates for high-frequency
more » ... igh-frequency environments such as super-Ohmic environments, where the coherent oscillations can grow exponentially as either the environment coupling or temperature are increased. The effect could be used as an experimental probe for high-frequency environments in such systems as molecular magnets, solid-state qubits, spin-polarized gases (neutrons or He3) or Bose-condensates.
doi:10.1103/physrevlett.107.210402 pmid:22181860 fatcat:n3av4kf6pbevlf5ygt36sepuce