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Control of Inter-dot Electrostatic Coupling in an Asymmetric Silicon Double Quantum Dot Operating at 4.5 K

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  • Physics

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Control of Inter-Dot Electrostatic Coupling by a Side Gate in a Silicon Double Quantum Dot Operating at 4.5K Control of Inter-Dot Electrostatic Coupling by a Side Gate in a Silicon Double Quantum Dot Operating at 4.5K Gento Yamahata1�, Tetsuo Kodera1, Hiroshi Mizuta2;3;4, Ken Uchida3;4, and Shunri Oda1;4 1Quantum Nanoelectronics Research Center, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro, Tokyo 152-8552, Japan 2School of Electronics and Computer Science, University of Southampton, Highfield, Southampton SO17 1BJ, U.K. 3Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro, Tokyo 152-8552, Japan 4SORST-JST, Chiyoda, Tokyo 102-0075, Japan Received June 24, 2009; accepted July 28, 2009; published online August 21, 2009 We report on electron transport measurements of a lithographically-defined silicon double quantum dot (DQD) coupled in series with a top gate and side gates. The structure of the top gate coupled uniformly to the DQD is suitable for realizing a few-electron regime. The obtained small DQD enables us to observe a clear honeycomb-like charge stability diagram at a temperature of 4.5K. The validity of the DQD structure is confirmed by theoretical calculations. Furthermore, we demonstrate successful modulation of the inter-dot electrostatic coupling by the side gate. Externally tunable coupling is essential for practical implementation of spin-based quantum information devices. # 2009 The Japan Society of Applied Physics DOI: 10.1143/APEX.2.095002 D ouble quantum dots (DQDs) are key structures to prepare, manipulate, and detect electron spins toward spin-based quantum information proces- sing.1) Coherent manipulation of individual and coupled electron spin states has been extensively studied in GaAs- based DQD devices.2–5) However, nuclear spins of the host materials cause electron spin decoherence via strong hyperfine coupling.2,3,6) In order to eliminate the effect, group IV materials, such as carbon, sili

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