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Lecture S.M. Frolov


02 March 2011 FWN-Building 5113.0202, Nijenborgh 4, 9747 AG, Groningen
Speaker: Dr. S.M. Frolov
Affiliation: Kavli Institute of Nanoscience, Delft
Title: Spin-orbit qubit in a nanowire
Date: Wed Mar 2, 2011
Start: 15.00
Location: FWN-Building 5113.0202
Host: C.H. van der Wal
Telephone: +31 50 363 4974


The Electron spin is a natural quantum two-level system with long coherence
times. This makes spin the leading candidate for solid state quantum computing.
A big challenge is to find a practical way of controlling spin on the nanoscale.
For instance, magnetic fields are hard to generate on a chip, especially at high
frequencies desired for quantum computing. A much preferred control knob is
the one that was the key to success for charge-based electronics – a gate voltage
or an electric field. It turns out that in semiconductors it is possible to couple
spin to electric fields. Through spin-orbit interaction we can control spin by
simply moving the electron around. I will describe a spin-orbit qubit that we
have realized in an InAs nanowire. We confined single electrons to quantum
dots and performed coherent spin manipulation using electric fields. The phase
of gigahertz microwave signals was used to implement two-axis qubit control,
and the difference in g-factors was used to selectively address nearby qubits.


Decoherence due to fluctuating nuclear spins remains a serious challenge for this
type of qubit, but coherence can already be extended using dynamical decoupling techniques.

Last modified:22 October 2012 2.31 p.m.