@article {1339, title = {Tunable Spin Qubit Coupling Mediated by a Multi-Electron Quantum Dot}, journal = {Physical Review Letters}, volume = {114}, year = {2015}, month = {2015/06/04}, pages = {226803}, abstract = {We present an approach for entangling electron spin qubits localized on spatially separated impurity atoms or quantum dots via a multi-electron, two-level quantum dot. The effective exchange interaction mediated by the dot can be understood as the simplest manifestation of Ruderman-Kittel-Kasuya-Yosida exchange, and can be manipulated through gate voltage control of level splittings and tunneling amplitudes within the system. This provides both a high degree of tuneability and a means for realizing high-fidelity two-qubit gates between spatially separated spins, yielding an experimentally accessible method of coupling donor electron spins in silicon via a hybrid impurity-dot system. }, doi = {10.1103/PhysRevLett.114.226803}, url = {http://arxiv.org/abs/1312.1711v3}, author = {V. Srinivasa and H. Xu and J. M. Taylor} }