Samuel J. Elman, Stephen D. Bartlett, Andrew C. Doherty


We propose and analyse a scheme for performing a long-range entangling gate for qubits encoded in electron spins trapped in semiconductor quantum dots. Our coupling makes use of an electrostatic interaction between the state-dependent charge configurations of a singlet-triplet qubit and the edge modes of a quantum Hall droplet. We show that distant singlet-triplet qubits can be selectively coupled, with gate times that can be much shorter than qubit dephasing times and faster than decoherence due to coupling to the edge modes. A two-qubit gate can take as little as 20 ns using parameters based on recent experiments, leading to predicted gate fidelities greater than 99%.