Abstract
摘要 |
Controlling decoherence is an issue of central importance to quantum information, and indeed to many areas of quantum mechanics, since loss of phase information diminishes or eliminates entirely any advantage quantum mechanics might provide over classical mechanics (such as the speed-up of certain calculational algorithms).. In this talk, I will discuss a recent effort in the battle against decoherence. For a system interacting with its environment, I will ask (and answer!) the following question: Are there states of the environment allowing for decoherence-free evolution of the system? Within a class of models describing a system in interaction with its environment, I will derive a necessary and sufficient condition on the Hamiltonian in order for decoherence-free evolution to be possible, and studied several extensions to more realistic contexts. Since it is unlikely that perfect control of the environment is possible, I will also assess the impact of imperfect state preparation and discuss how to choose an initial state that minimizes decoherence when state preparation cannot avoid it altogether. |
