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Getting through to a qubit by magnetic solitons

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Getting through to a qubit by magnetic solitons
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62
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We propose a method for acting on the spin state of a spin- 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- 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.
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Transcript: English(auto-generated)
Hi, I'm Darniel Nussi, and this is the video abstract of the paper Getting Through the Single Fluid by magnetic solvents, written together with Alessandro Pucoli, N. Geroaia and Paolo De Nussi. Addressing, initializing and possibly controlling one single fluid
are essential steps in order to put into actions a quantum device. As these actions involve the use of some control apparatus, which is usually some atmospheric instrument, it can be difficult to obtain such results without scoring a quantum feature of the fluid or disturbing other nearby fluids. The solution to this problem can be to put the control apparatus far from the target
and then convey the proper signal to the target itself. In this work, we showed that it is impossible possible to control a fluid state using a discretized member chain as the wire and a magnetic solitor as the proper signal.
Solitons can be regarded as good signals because they travel at constant velocity with stability against noise and disorder, and they are also localized as based on time, looking signal to the past signal, but without being spread by the solution. Moreover, within the same model, one can have solitons with different shapes,
giving the freedom to choose the proper signal to control the qubit without changing the wire. Having chosen a discretized member chain as its official line, we now have to deal with the problem of how to generate the proper signal in the chain. As you can see by this discretized system, which represents a chain of covered pendula,
it seems to be possible to generate a solitons just tapped with the proper action just on the edge of the chain. In analogous piece, we simulate the dynamics generated by time-dependent boundary condition, schematized as the magnetic field acting on the first pin of the chain,
and whose time dependence is given by the solitons one wants to inject. The main results are that the dynamical configuration is indegenerated and it possesses the essential features of the injected shape. This picture holds holes in presence of thermal noise,
as it is shown in the pictures where the valves of the third component of the chain's pins are plotted as a function of position and dimensional style. Coming back to the original problem, we now have that the soliton traveling around the chain will generate an effective magnetic field,
proportional to the sum of the contribution of all the spins near to the qubit, each being weighted with a function decreasing with the least time qubit itself. Under its assumptions, qubit dynamics is described by the following Hamiltonian,
which represents the Hamiltonian of the spin-one-half qubit in an identical field, where pin-one is a uniform field which identifies the direction of third axis. The typical dynamics resulting from this scheme is shown in the animation.
The soliton starts moving far from the qubit and the block vector describing qubit states is aligned with the uniform field. When the soliton is close to the qubit, the block vector starts moving from the initial configuration. After the transit of the soliton is complete, the vector describing qubit states keeps making a possession motion,
with the component along the third axis constant, unless it is completely flipped. This kind of dynamics can be interesting for what concerns qubit state manipulation, as the transit of the soliton near to the qubit leaves a permanent change in qubit state. In the figures are shown two examples of density maps, reporting the syntactic values of the third component of the block vector,
describing the qubit as a function of two of the parameters, while the others are fixed. As can be seen, the scheme is effective within an entire region of armature space, rather than isolated points, meaning that a perfect tuning of parameters is not necessary to accomplish a particular goal. So, I hope you enjoyed it,
and I want to remember that this is just a lot of this work, but if you want to know the whole story, you can find me the full details at the article. Thank you for your attention.