May decoherence be reversible?

[naima]

I found an interesting paper
here a two level system is measured by a harmonic oscillator(the apparatus). the apparatus is coupled to its environment, a bath of oscillators.
The article shows how the reduced matrix of S+ A decoheres (the off diagonal elements tend to zero).
I am looking for a similar calculation with an environment reduced to a single oscillator.
I think that we would find the off diagonal initial values after some time.
So there would be a revival of coherence in a cyclic process.
Have you a link?

 

[Demystifier]

I am looking for a similar calculation with an environment reduced to a single oscillator.
I think that we would find the off diagonal initial values after some time.
So there would be a revival of coherence in a cyclic process.

You are right, decoherence is reversible. When environment consists of a small number degrees of freedom, the typical recurrence time is relatively small. But when the number N of environment degrees of freedom is large, the recurrence time increases exponentially with N, implying that it appears irreversible for all practical purposes.