Berlin 2012 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 11: Transport: Quantum Coherence and Quantum Information Systems 2 (jointly with MA and HL)
TT 11.1: Vortrag
Montag, 26. März 2012, 15:00–15:15, BH 243
Control Pulse Engineering for Fast Controlled-Z Gates — •Daniel Egger, Seth Taylor Merkel, and Frank Wilhelm — Universität des Saarlandes, Saarbrücken, Germany
When manipulating quantum systems it is key to do so before decoherence destroys the fragile states. For quantum computing this sets a time within which the desired qubit manipulations can be done. To increase the number of computations, either the coherence times must be increased or the gate durations must be decreased with the help of Optimal Control Theory. In the following work we show how Gradient Pulse Shape Engineering [1] can be used to optimize the time taken to perform a controlled-Z gate in the framework of the RezQu architecture [2]: two qubits, sufficiently far apart, are coupled to a bus resonator. The only controls considered are the two qubit-bus detunings. All elements have three levels to account for leakage. Additionally the finite bandwidth of the electronics is taken into account though an impulse response function. We give a value of the critical time below which a high fidelity gate can no longer be realized and explore what affects the control pulses. For the case of phase qubits we find that a controlled-Z gate with an error of 10−4 can be realized in 27 ns. Furthermore, the found control pulses are ready to be tested experimentally.
N. Khaneja, J. Magn. Reson. 172, 296
M. Mariantoni, Science 334, 6052