Artikelbeschreibung
Electron spins trapped in solid-state systems can
exhibit strong hyperfine interactions with a nuclear
spin reservoir, which is normally fluctuating and
randomly oriented. As this represents a fundamental
decoherence mechanism for the electron spin, several
theoretical scenarios to suppress this effect in
semiconductor quantum dots (QDs) have been proposed.
However, implementing these proposals requires a
deeper understanding of the properties of the QD
nuclear spin ensemble and of the possibilities to
manipulate the nuclear spins. The present work
describes an experimental assessment of these topics.
Optical preparation and detection of the spin and
energy of QD electrons was used to manipulate and
measure the average nuclear spin polarization (NSP)
in an individual QD. Studying NSP as a function of
external paramters such as magnetic fields, QD charge
and of time revealed the nonlinear character of
electron-nuclear spin coupl
ing and led to the
identification of the dominant spin-relaxation
mechanisms for QD nuclei. Ultimately, further
understanding of the subtle interactions that govern
the QD nuclear spin system could enable us to improve
the spin coherence time of QD electrons.
Personeninformation
P.M. studied Physics from 1998 to 2004 both at ETH Zürich and ENS
Paris. After obtaining his Diploma he worked as a Research
Assistant at JILA (Univerity of Colorado). From 2005 to 2008 he
graduated with the present work under the supervision of Prof. A.
Imamoglu (ETH Zürich). P.M. is currently a postdoctoral Research
Scholar at Harvard University.
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