Quantum repeaters based on individual electron spins and nuclear-spin-ensemble memories in quantum dots

Inspired by recent developments in the control and manipulation of quantum dot nuclear spins, which allow for the transfer of an electron spin state to the surrounding nuclear-spin ensemble for storage, we propose a quantum repeater scheme that combines individual quantum dot electron spins and nuclear-spin ensembles, which serve as spin-photon interfaces and quantum memories respectively. We consider the use of low-strain quantum dots embedded in high-cooperativity optical microcavities. Quantum dot nuclear-spin ensembles allow for the long-term storage of entangled states, and heralded entanglement swapping is performed using cavity-assisted gates. We highlight the advances in quantum dot technologies required to realize our quantum repeater scheme which promises the establishment of high-fidelity entanglement over long distances with a distribution rate exceeding that of the direct transmission of photons.

Spin-polarized dwell time for electrons in a δ-doped magnetic nanostructure

We theoretically investigate dwell time for electrons in a magnetic nanostructure with a [Formula: see text]-doping, which is formed on [Formula: see text] heterostructure by depositing a ferromagnetic (FM) stripe. We find that dwell time depends strongly on electron-spins owing to Zeeman coupling and broken symmetry. We also demonstrate that spin-polarized dwell time can be manipulated by [Formula: see text]-doping. Thus, electron spins can be separated in time dimension and such a magnetic nanostructure can be employed as a structurally-controllable temporal spin splitter for spintronics device applications.