In quantum nanoelectronics, one of the paradigms is to use quantum mechanics in order to build more efficient nanoprocessors. In this context, the electron spin has been identified as a good degree of freedom to store and to manipulate quantum information efficiently. The defined building block of this quantum computer strategy is called a spin qubit. Towards this goal, intense experimental efforts have been invested in AlGaAs heterostructures where quantum dots with only one electron can be realized. In such a system, all the basic operations of a quantum nanoprocessor have been demonstrated in spin qubits and they constitute a very promising platform to study spin dynamics at the single electron level.
To scale up the spin qubit system, one has to be able to make two distant qubits interacting. The protocol consists in the exchange of a quantum particle between the two qubits. In this respect, one can take advantage of the fact that a single electron can be transported within nanostructures. Understanding how to preserve quantum information stored in the spin of an electron while transferring it between two quantum dot systems is of crucial importance. Recently, the PI has realized a first important step towards this goal, namely the realization of efficient single electron transfer between two distant quantum dots on a timescale faster than the spin decoherence time
Here we propose to give a new dimension to the spin qubit system by investigating quantum coherence and manipulation of a single flying electron spin. Displacing coherently a single electron spin between two distant quantum dots not only represents a viable solution towards entanglement between distant qubits but also opens new ways of manipulating coherently electron spins via spin-orbit interaction. The new knowledge expected from these experiments is likely to have a broad impact extending from quantum spintronics to other areas of nanoelectronics.
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