Darmstadt 2008 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 28: Poster Quanteninformation

Q 28.20: Poster

Dienstag, 11. März 2008, 16:30–19:00, Poster C2

Application of optimal control techniques in scalable ion trap quantum logic — •Ulrich Poschinger, Kilian Singer, and Ferdinand Schmidt-Kaler — Institut für Quanteninformationsverarbeitung, Universität Ulm, Albert-Einstein-Allee 11, 89069 Ulm

Strings of laser cooled ions in a Paul trap provide a yet unmatched degree of quantum control[1]. The drawback of this concept lies in the limited scalability, which can be overcome by operating a microstructured array of Paul traps and shuttling the ions between different trap sites. The shuttling operations are carried out by dynamically changing the confining voltages at the trap segments. They have to be fast, robust and should not contribute excess energy to the ion qubit as this would spoil subsequent quantum logic operations. This setting suggests the application of optimal control (OCT) techniques. We present numerical results showing that OCT should indeed make such shuttling operations possible[2]. Furthermore, quantum logic logic gates can benefit from OCT as well since achieving high fidelities is crucial for attaining the quantum error correction threshold[3]. We demonstrate numerically that shaped pulse sequences obtained by OCT allow for the implicit compensation of parameter offsets. Analogously to NMR experiments, the logic operations can therefore be robustified[4].

[1] H.Häffner et al., Nature 438, 643 (2005)

[2] S. Schulz et al., Progress of Physics, Wiley 54, No. 8-10, 648 (2006)

[3] C. Roos, arXiv:0710.1204v3 (2007)

[4] N. Timoney et al. quant-ph/0612106 (2006)