05.70.+o Quantum information & quantum control

Communication at the quantum speed limit along a spin chain


Michael Murphy, Simone Montangero, Vittorio Giovannetti, Tommaso Calarco
arXiv:1004.3445v1 [quant-ph] (http://arxiv.org/abs/1004.3445v1)

Spin chains have long been considered as candidates for quantum channels to facilitate quantum communication. We consider the transfer of a single excitation along a spin-1/2 chain governed by Heisenberg-type interactions. We build on the work of Balachandran and Gong [1], and show that by applying optimal control to an external parabolic magnetic field, one can drastically increase the propagation rate by two orders of magnitude. In particular, we show that the theoretical maximum propagation rate can be reached, where the propagation of the excitation takes the form of a dispersed wave.

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