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Quantum-Dot Spin-State Preparation with Near-Unity Fidelity. M. Atatüre, J. Dreiser, A. Badolato, A. Högele, K. Karrai, A. Imamoglou Science 312 , 551 (2006). 30.01.07. Overview. Optical controlling of spin in quantum-dots at 4 K High fidelity spin state preparation due to Pauli blockade
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Quantum-Dot Spin-State Preparation with Near-Unity Fidelity M. Atatüre, J. Dreiser, A. Badolato, A. Högele, K. Karrai, A. Imamoglou Science 312, 551 (2006) 30.01.07
Overview • Optical controlling of spin in quantum-dots at 4 K • High fidelity spin state preparation due to Pauli blockade • Self-assembled InAs/GaAs QD
Four-Level System for B=0 EF EF g (s+) Spontaneous spin-flip Raman scattering • (s-) Laser absorbtion EF EF x Hyperfine induced spin-flip
Four-Level System for B>0 EF EF g (s+) Spontaneous spin-flip Raman scattering • (s-) Laser absorbtion EF EF x Hyperfine induced spin-flip
Four-Level System for B>0 with Repump Laser EF EF g (s+) g (s-) • (s+) Laser absorbtion • (s-) Laser absorbtion EF EF x Hyperfine induced spin-flip
G (s-) How It Works Blocked! EF
Results: Laser Absorption Repump Laser detuned by 6 GHz (Zeeman splitting) Absorbtion suppressed due to Pauli blockade Absorbtion due to cotunneling Linewidth of the transition X-
Results: High Fidelity Theoretical model Repump Laser Experimental data Exponential fit
Conclusions and Outlook • High-fidelity spin preparation (99.8 %) • Spin cooling down to 20 mK (T=4 K) • Works for both spins • Prepare arbitrary superpostition of spin states • Tune g by changing the magnetic field orientation with respect to the confinement axis EF EF g