Hamburg 2009 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 56: Poster IV
Q 56.45: Poster
Donnerstag, 5. März 2009, 16:30–19:00, VMP 9 Poster
Construction of a Fast Two-Qubit Gate for Ultracold Atoms Using Optimal Control — •Michael Goerz1, Christian Schwenke1, Tommaso Calarco2, and Christiane P. Koch1 — 1Institut für Theoretische Physik, Freie Universität Berlin, Germany — 2Institut für Quanteninformationsverarbeitung, Universität Ulm, Germany
We study the implementation of a two-qubit gate for ultracold Ca atoms trapped in an optical lattice. The qubits are encoded in the internal electronic states of the atoms. The dynamics of the system are driven by shaped laser pulses. A two-qubit CNOT (π/2-phasegate) can be obtained by applying an appropriate pulse to two neighboring atoms, shifting their relative phase. An optimized pulse, producing the required unitary transformation, can be generated from an initial guess pulse via the Krotov method of Optimal Control Theory.
The main difficulty is that a laser pulse driving the molecular (two-qubit) phase will aways drive the atomic (single-qubit) phases as well. We present our findings in addressing this problem, depending on constraints such as lattice constants, pulse intensity and complexity. Our goal consists in achieving short, high fidelity pulses performing the target two-qubit π/2-gate.