Electron teleportation with quantum dot arrays

Teleportation is a spectacular manifestation of quantum mechanics, and altogether an essential element of future information processing1 . It means reconstructing the (unmeasured) quantum state of a given object at a different location, without direct transfer of the object. Bennett et al.2 showed that EPR entanglement3 can be used for teleportation, which was recently experimentally demonstrated with photons4 . Here an implementation of this scheme is proposed with electrons in a mesoscopic circuit. It relies on Coulomb blockade and uses two superconductors as a generator and as an analyzer of entangled electrons5,6,7 . As a result, the spin state of electrons can be teleported through quantum dot arrays. Electron transport in nanostructures and propagation of photons in waveguides bear strong analogies. These are illustrated for example by the Hanbury-Brown and Twiss intensity and noise correlations for photons and electrons . The non–local character of quantum mechanics has been probed by quantum optics experiments , using two–photon entangled states. It results that correlations between particles persist although the interactions between them have been switched off. It is now especially relevant to test non-locality and its striking consequences with massive particles in solid-state devices. Using the spin degree of freedom of electrons is mostly promising. Actually, recent evidence for long spin coherence times in doped semiconductors opened the way to spin-based quantum computation . Here a protocol for electron spin teleportation based on the principle of Ref. 2 is presented. It relies on current nanofabrication techniques using quantum dots and a superconducting circuit. in contrast with a previous proposal with excitons , it involves steady state transport in a mesoscopic circuit and operates with purely electrical control. In Ref. 4 , an entangled photon pair is produced by parametric-down conversion. Another photon which carries the polarization state to be teleported is measured in an entangled state formed with one of the pair constituents, using of a two–photon interferometer. This measurement is effectively a projection process, and the remaining photon acquires the same state as the initial one. In order to implement this proposal with spin–1/2 electrons in mesoscopic circuits, one needs both a source of pairs of entangled electrons, and another