Getting through to a qubit by magnetic solitons

We propose a method for acting on the spin state of a spin- ##IMG## [http://ej.iop.org/images/1367-2630/17/8/083053/njp517953ieqn1.gif] {$\frac{1}{2}$} localized particle, or qubit , by means of a magnetic signal effectively generated by the nearby transit of a magnetic soliton, there conveyed through a transmission line. We first introduce the specific magnetic soliton of which we will make use, and briefly review the properties that make it apt to represent a signal. We then show that a Heisenberg spin chain can serve as transmission line, and propose a method for injecting a soliton into the chain by acting just on one of its ends. We finally demonstrate that the resulting magnetic pulse can indeed cause, just passing by the spin- ##IMG## [http://ej.iop.org/images/1367-2630/17/8/083053/njp517953ieqn2.gif] {$\frac{1}{2}$} localized particle embodying the qubit, a permanent change in its spin state, thus realizing the possibility of getting through to a single, localized qubit, and manipulating its state. A thorough analysis of how the overall dynamical system operates depending on the setting of its parameters demonstrates that fine tuning is not necessary as there exists an extended region in the parameters space that corresponds to effective functioning. Moreover, we show that possible noise on the transmission line does not invalidate the scheme.