Abstract
We investigate quantum dynamics in phase-space regions containing “shearless tori.” We show that the properties of these peculiar classical phase-space structures—important to the dynamics of tokamaks—may be exploited for quantum information applications. In particular we show that shearless tori permit the nondispersive transmission of localized wave packets. The quantum many-body Hamiltonian of a Heisenberg ferromagnetic spin chain, subjected to an oscillating magnetic field, can be reduced to a classical one-body “image” dynamical system which is the well-studied Harper map. The Harper map belongs to a class of Hamiltonian systems (nontwist maps) which contain shearless tori. We show that a variant with sinusoidal time driving “driven Harper model” produces shearless tori which are especially suitable for quantum state transfer. The behavior of the concurrence is investigated as an example.
- Received 20 January 2008
DOI:https://doi.org/10.1103/PhysRevE.77.055203
©2008 American Physical Society