Manipulation of local and non-local spin entanglement with quantum dots

Orateur : Seigo TARUCHA (University of Tokyo, Japan)

Quantum entanglement is one of the most exotic quantum phenomena in solid-state systems and has been well studied for BCS Cooper pairs and Kondo singlet states. Quantum dots can be a powerful tool to explore the microscopic picture of quantum entanglement in a controlled manner and offer unique applications to quantum information processing with quantum entanglement as the central concept. In this talk I will discuss control of local and non-local spin entanglement with quantum dots. The local entanglement is typically the case for spin singlet states in single or multiple quantum dots, and their manipulation enables us to prepare universal sets of logical gates in quantum computation. We have recently used a two spin qubit gate of combined spin rotation and spin exchange coupling to control spin entanglement. The concept of non-local entanglement is well established for correlated photon pairs, which have been used to implement quantum teleportation, but not yet for electron spins in solid state systems. We study non-local entanglement using a double dot Josephson junction. The splitting of Cooper pairs into both dots may contribute to generate supercurrent, because Cooper pair tunnelling through the same dot is strongly suppressed by the electron-electron interaction. We observe the supercurrent depending on the double dot charge state and discuss the contribution from the split Cooper pair tunnelling to the supercurrent.

Télécharger dans mon agenda