title: Single-electron Spin Resonance in a Quadruple Quantum Dot.
abstract: Electron spins in semiconductor quantum dots are good candidates of quantum bits for quantum information processing. Basic operations of the qubit have been realized in recent years: initialization, manipulation of single spins, two qubit entanglement operations, and readout. Now it becomes crucial to demonstrate scalability of this architecture by conducting spin operations on a scaled up system. Here, we demonstrate single-electron spin resonance in a quadruple quantum dot. A few-electron quadruple quantum dot is formed within a magnetic field gradient created by a micro-magnet. We oscillate the wave functions of the electrons in the quantum dots by applying microwave voltages and this induces electron spin resonance. The resonance energies of the four quantum dots are slightly different because of the stray field created by the micro-magnet and therefore frequency-resolved addressable control of each electron spin resonance is possible.
authors.affiliation: Center for Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.|Department of Applied Physics, University of Tokyo, Bunkyo, Tokyo 113-8656, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Otsuka
authors.affiliation: Center for Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.|Department of Applied Physics, University of Tokyo, Bunkyo, Tokyo 113-8656, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakajima
authors.affiliation: Center for Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.|Department of Applied Physics, University of Tokyo, Bunkyo, Tokyo 113-8656, Japan.
authors.forename: Matthieu R
authors.initials: MR
authors.lastname: Delbecq
authors.affiliation: Center for Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Amaha
authors.affiliation: Center for Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.|Department of Applied Physics, University of Tokyo, Bunkyo, Tokyo 113-8656, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Yoneda
authors.affiliation: Center for Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.|Department of Applied Physics, University of Tokyo, Bunkyo, Tokyo 113-8656, Japan.
authors.forename: Kenta
authors.initials: K
authors.lastname: Takeda
authors.affiliation: Center for Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Giles
authors.initials: G
authors.lastname: Allison
authors.affiliation: Center for Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.|Department of Applied Physics, University of Tokyo, Bunkyo, Tokyo 113-8656, Japan.
authors.forename: Takumi
authors.initials: T
authors.lastname: Ito
authors.affiliation: Center for Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.|Department of Applied Physics, University of Tokyo, Bunkyo, Tokyo 113-8656, Japan.
authors.forename: Retsu
authors.initials: R
authors.lastname: Sugawara
authors.affiliation: Center for Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.|Department of Applied Physics, University of Tokyo, Bunkyo, Tokyo 113-8656, Japan.
authors.forename: Akito
authors.initials: A
authors.lastname: Noiri
authors.affiliation: Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum, Germany.
authors.forename: Arne
authors.initials: A
authors.lastname: Ludwig
authors.affiliation: Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum, Germany.
authors.forename: Andreas D
authors.initials: AD
authors.lastname: Wieck
authors.affiliation: Center for Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.|Department of Applied Physics, University of Tokyo, Bunkyo, Tokyo 113-8656, Japan.|Quantum-Phase Electronics Center, University of Tokyo, Bunkyo, Tokyo 113-8656, Japan.|Institute for Nano Quantum Information Electronics, University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505, Japan.
authors.forename: Seigo
authors.initials: S
authors.lastname: Tarucha