This title appears in the Scientific Report : 2014 

Two-qubit couplings of singlet-triplet qubits mediated by one quantum state
Mehl, Sebastian (Corresponding Author)
Bluhm, Hendrik / DiVincenzo, David
Theoretische Nanoelektronik; PGI-2
Physical review / B, 90 (2014) S. 045404
College Park, Md. APS 2014
10.1103/PhysRevB.90.045404
Journal Article
Spin-based and quantum information
OpenAccess
Please use the identifier: http://dx.doi.org/10.1103/PhysRevB.90.045404 in citations.
Please use the identifier: http://hdl.handle.net/2128/7829 in citations.
We describe high-fidelity entangling gates between singlet-triplet qubits (STQs) which are coupled via onequantum state (QS). The QS can be provided by a quantum dot itself or by another confined system. Theorbital energies of the QS are tunable using an electric gate close to the QS, which changes the interactionsbetween the STQs independent of their single-qubit parameters. Short gating sequences exist for controlled NOT(CNOT) operations. We show that realistic quantum dot setups permit excellent entangling operations with gateinfidelities below 10−3, which is lower than the quantum error correction threshold of the surface code. Weconsider limitations from fabrication errors, hyperfine interactions, spin-orbit interactions, and charge noise inGaAs and Si heterostructures.