Regensburg 2016 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 58: Transport: Poster Session
TT 58.22: Poster
Mittwoch, 9. März 2016, 15:00–18:30, Poster D
Two-qubit Quantum Gates on Qubit Chains — •Raphael Salchner1, Daniel Egger2, and Frank Wilhelm-Mauch3 — 1Universität des Saarlandes, Saarbrücken, DE — 2Universität des Saarlandes, Saarbrücken, DE — 3Universität des Saarlandes, Saarbrücken, DE
Quantum computers are of huge interest for scientific research and applications for their ability to solve exponentially scaling problems. There are several physical implementations of quantum bits, one of them is the superconducting qubit which is built out of Josephson junctions [1]. Usually two qubits are coupled via a resonator, but research has shown that quantum gates can be executed via direct coupling of the qubits [2].
We investigate the effect of weakly coupled idling qubits on two-qubit gate operations.
We use numerical optimal control algorithms (GRAPE, Nelder-Mead Simplex) [3] to find control pulses for the Controlled-Z gate, which is important for entangling two qubits.
The results indicate that already one spuriously coupled idling qubit can cause the optimization to reach less than 99% gate fidelity, independent of the positioning of the qubits in the circuit. Additionally, several attempts are made to find control pulses that compel the desired gate, all without relevant success.
D. diVincenzo, "Quantum Information Processing: Lecture Notes",
44th IFF Spring School vol. 52, FZ Jülich (2013)
R. Barends et al, arXiv:1402.4848
Navin Khaneja et al., J. Magn. Reson. 172, 296 (2005)