Decoherence of an Electron Spin Qubit due to Nuclear Spin

Sonderforschungsbereich TRR 160
Kohärente Manipulation wechselwirkender Spinanregungen in maßgeschneiderten Halbleitern
Seminarankündigung
Mittwoch, 11.05.2016, 10:15 Uhr
Raum P1-02-323
“Decoherence of an Electron Spin Qubit
due to Nuclear Spin:
Effects of Nuclear Electric Quadrupole Moments”
Vortragender: Dr. Erik Welander
Universität Münster
Decoherence of an Electron Spin Qubit due to Nuclear Spin:
Effects of Nuclear Electric Quadrupole Moments
Erik Welander
Institut für Festkörpertheorie, Universität Münster
An electron confined to a semiconductor quantum dot has been proposed to realize
a quantum bit by virtue of its spin. By interaction between the electron spin and some
104 − 105 nuclear spins of the atoms in the quantum dot, the qubit loses coherence over
time and the quantum information is partially lost. One way of restoring the information
is to apply an electromagnetic pulse causing the electron spin evolution to reverse direction
and results in an electron spin echo. However, time evolution of the nuclear spins degrades
the quality of the electron spin echo, which suggests searching for methods preventing the
nuclear spins from evolving.
In this talk, we will discuss magnetic dipole moments and electric quadrupole moments
of the atomic nuclei, and their contributions to the time evolution of the nuclear spins.
We will also look at the combined effect of nuclear electric quadrupole moments with
a partial polarization of the nuclear spins, which significantly reduces the exchange of
atomic nuclear spin.
References:
E. Welander, E. Chekhovich, A. Tartakovskii, and G. Burkard, arXiv:1405.1329 (2014).
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