title: Conditional rotation of two strongly coupled semiconductor charge qubits.
abstract: Universal multiple-qubit gates can be implemented by a set of universal single-qubit gates and any one kind of entangling two-qubit gate, such as a controlled-NOT gate. For semiconductor quantum dot qubits, two-qubit gate operations have so far only been demonstrated in individual electron spin-based quantum dot systems. Here we demonstrate the conditional rotation of two capacitively coupled charge qubits, each consisting of an electron confined in a GaAs/AlGaAs double quantum dot. Owing to the strong inter-qubit coupling strength, gate operations with a clock speed up to 6 GHz have been realized. A truth table measurement for controlled-NOT operation shows comparable fidelities to that of spin-based two-qubit gates, although phase coherence is not explicitly measured. Our results suggest that semiconductor charge qubits have a considerable potential for scalable quantum computing and may stimulate the use of long-range Coulomb interaction for coherent quantum control in other devices.
authors.affiliation: Key Laboratory of Quantum Information, CAS, University of Science and Technology of China, Hefei, Anhui 230026, China.|Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
authors.forename: Hai-Ou
authors.initials: HO
authors.lastname: Li
authors.affiliation: Key Laboratory of Quantum Information, CAS, University of Science and Technology of China, Hefei, Anhui 230026, China.|Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Cao
authors.affiliation: Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.|Department of Optics and Optical Engineering, University of Science and Technology of China, Hefei, Anhui 230026, China.
authors.forename: Guo-Dong
authors.initials: GD
authors.lastname: Yu
authors.affiliation: Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.|Department of Optics and Optical Engineering, University of Science and Technology of China, Hefei, Anhui 230026, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Xiao
authors.affiliation: Key Laboratory of Quantum Information, CAS, University of Science and Technology of China, Hefei, Anhui 230026, China.|Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
authors.forename: Guang-Can
authors.initials: GC
authors.lastname: Guo
authors.affiliation: Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA.
authors.forename: Hong-Wen
authors.initials: HW
authors.lastname: Jiang
authors.affiliation: Key Laboratory of Quantum Information, CAS, University of Science and Technology of China, Hefei, Anhui 230026, China.|Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
authors.forename: Guo-Ping
authors.initials: GP
authors.lastname: Guo