QDev Seminar: David M. Zajac – University of Copenhagen

QDev Seminar: David M. Zajac

Department of Physics, Princeton University

Two Qubit Control of Single Electron Spin Qubits in Silicon

Realizing robust two qubit gates has been one of the major hurdles for semiconductor spin qubits. Extremely long coherence times and high fidelity single qubit gates have been realized in spin qubits, but conventional exchange based two qubit couplings have suffered from a high sensitivity to charge noise. I will demonstrate a two qubit CNOT gate based on a conditional spin transition in a regime where the exchange interaction is small compared to the other terms in the two qubit Hamiltonian. Single qubit Rabi frequencies greater than 10 MHz are achieved by modulating the position of the two electrons in a spatially non-uniform magnetic field, while two qubit coupling is enabled by controlling the overlap of the two electronic wavefunctions. Entanglement is verified by measuring the two qubit density matrix, with a CNOT operation time of ~200 ns.