
Jul 16 2013
WITS Node Seminar: Dr Hermann Uys (CSIR)
Dear all
Here are the details of the NITheP seminar to be held on Tuesday 16 July at the usual time (13:20) and place P216.
The speaker is Dr. Hermann Uys, from the CSIR. The title and abstract of his talk are below.
Efficient Quantum stateestimation and feedback on trapped ions using unsharp measurement
Parameter estimation and closed–loop feedback control is ubiquitous in every branch of classical science and engineering. Similar control of quantum systems is usually impossible due to two difficulties. Firstly, quantum phenomena are often short lived due to decoherence, and secondly, attempts to estimate the state of a quantum system through projective measurement, strongly disrupt the dynamics. One alternative is to use unsharp measurements, which are less invasive, but lead to less information gain about the system. A sequence of unsharp measurements, however, carried out in the presence of stronger dynamics, promise realtime state monitoring and control via feedback. Such measurements can be realised by periodically entangling an auxiliary quantum system with the target quantum system, and then carrying out projective measurements on the auxiliary system only. In this talk we discuss methods for estimating both the state of a twolevel system and the strength of its coupling to a drive field using unsharp measurement. We then model closed loop feedback control of the twolevel dynamics, and explore the level of control over the parameter regime of the model. Finally, we summarize the prospects for implementing the scheme using trapped ions.
contact
 NITheP Stellenbosch node
 Ms Monique Louw
National Institute for Theoretical Physics
Private Bag X1
Matieland,
Stellenbosch, South Africa,7602  Phone: +27 (0)21 808 2649  Fax: +27 (0)218083862
 NITheP Gauteng node
 Rene Kotze (contact person for the NITheP WITS node)
Physical address: University of Witwatersrand
School of Physics
Jan Smuts Avenue
Braamfontein
JHB
 Phone: 27 (0)218082653  Fax: 27 (0)218083862
 NITheP KZN node
 Ms Nelisiwe Mncube
National Institute for Theoretical Physics
University of KwaZuluNatal
Private Bag x54001
Durban
4000
South Africa
 Phone: 27 (0)31 260 7570  Fax: 27 (0)31 260 8090
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