Düsseldorf 2007 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 57: Quanteninformation (Quantencomputer II)
Q 57.8: Vortrag
Donnerstag, 22. März 2007, 16:00–16:15, 5L
Quantum gates for optical transition qubits in ion trap — •Kihwan Kim1, Mark Riebe1, Michael Chwalla1, Thomas Monz1, Philipp Schindler1, Hartmut Häffner2, Christian Roos2, Wolfgang Hänsel1, Timo Körber2, Piet Schmidt1, and Rainer Blatt1,2 — 1Institute für Experimentalphysik, Universität Innsbruck, Austria — 2Institut für Quantenoptik und Quanteninformation, Austria
Qubits in ion trap quantum computation have been implemented at the long lived atomic states of either micro wave transitions or optical transitions. To realize a controlled-NOT gate, quantum gate operations have been studied theoretically and experimentally that use spin-dependent forces on hyperfine qubits. For qubits encoded in optical transitions, however, only controlled-NOT gates of Cirac-Zoller have been investigated so far [1,2]. Here, we show that similar forces to spin dependent one can also be employed for qubits on optical transitions. In contrast to hyperfine qubits, we find that the forces on optical quadrupole transitions have the following interesting properties: (1) Spontaneous photon scattering rates are low, (2) σz spin dependent forces can be be applied to magnetic-field insensitive states, (3) maximum coupling strength is achieved in a pair of co-propagating laser beams, which makes the gate robust against phase errors from optical path length fluctuations. We discuss the physics behind the gate operation and discuss its sensistivity against experimental imperfections.
[1] F. Schmidt-Kaler, et al., Nature 422, 408 (2003).
[2] M. Riebe, et al., Phys. Rev. Lett. 97, 220407 (2006).