2009 APS March Meeting
Volume 54, Number 1
Monday–Friday, March 16–20, 2009;
Pittsburgh, Pennsylvania
Session D4: Spin Qubits in Quantum Dots
2:30 PM–5:30 PM,
Monday, March 16, 2009
Room: 306/307
Sponsoring
Units:
GQI DCMP
Chair: Jason Petta, Princeton University
Abstract ID: BAPS.2009.MAR.D4.2
Abstract: D4.00002 : Locking electron spins into resonance by electron-nuclear feedback*
3:06 PM–3:42 PM
Preview Abstract
Abstract
Author:
Katja Nowack
(Delft University of Technology)
All basic building blocks for spin-based quantum information
processing
using electron spins in GaAs quantum dots have recently been
realized.
Recent experiments have shown single-shot read-out of an
individual spin
[1], the implementation of the SWAP gate [2] and (magnetically
induced)
coherent single electron spin rotations [3]. However, the main
drawback of
using electron spins in a GaAs environment is the short spin
coherence time,
which is measured to be in the nanosecond range [2,4]. The source
of this
fast decoherence is the hyperfine interaction of the localized
electron spin
with the randomly fluctuating nuclear spins of the host lattice. The
fluctuations of the nuclear spins have to be reduced to extend
the electron
spin coherence time. We therefore study the electron-nuclear spin
interaction and use magnetically driven spin resonance to control
the
electron spin and indirectly manipulate the nuclear spins.
We apply continuous microwave excitation to the electron spin and
observe
strong electron-nuclear feedback. One experimental signature of this
feedback is the locking of the electron spin system into
resonance with the
microwaves. Once the electron spin is locked into resonance, this
resonance
condition remains fullfilled even when the external magnetic
field or the
microwave frequency is changed. This is due to dynamically build
up nuclear
polarizations (up to 500 mT) which generally counteract the external
magnetic field. Locking of the electron spin system into
resonance might
indicate that the nuclear polarization exhibits stable
configurations where
fluctuations of the nuclear distribution are reduced [5].
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References
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[1] J. M. Elzerman et al. , \textit{Nature} \textbf{430}, 431 (2004)
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[2]. J. R. Petta et al., \textit{Science} \textbf{309}, 2180 (2005).
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[3] F. H. L. Koppens et al., \textit{Nature }\textbf{442}, 766
(2006).
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[4] F. H. L. Koppens et al., \textit{Phys. Rev. Lett.}
\textbf{100}, 236802 (2008).
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[5] J. Danon and Yu. V. Nazarov, \textit{private communication}.
*Supported by the Dutch Organization for Fundamental Research on Matter (FOM) and the Netherlands Organization for Scientific Research (NWO).
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2009.MAR.D4.2