# Mainz 2017 – wissenschaftliches Programm

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# Q: Fachverband Quantenoptik und Photonik

## Q 47: Quantum Computing I

### Q 47.2: Vortrag

### Donnerstag, 9. März 2017, 15:00–15:15, P 2

**Adaptive selective addressing of microwave-driven trapped ion qubits** — •Patrick Huber, Theeraphot Sriarunothai, Sabine Wölk, Gouri Giri, and Christof Wunderlich — Department Physik, Universität Siegen, 57068 Siegen, Germany

Cold ions stored in Paul traps are well suited for experiments in quantum information science. Applying a spatially varying magnetic field results in a MAgnetic Gradient Induced Coupling (MAGIC) between ions and allows for conditional quantum dynamics. Due to this gradient qubit resonances are individually shifted and become position dependent, thereby making them addressable in frequency space. We apply microwave pulses to realize single qubit gates, to control conditional gates with several ions, and for dynamical decoupling. Such quantum gates rely on the precise knowledge of qubit resonance frequencies that may, however, vary during the execution of a quantum algorithm. Here we report on the implementation of adaptive individual addressing of trapped ion qubits, that is, we measure resonance frequencies periodically using Ramsey interferometry and adapt the microwave pulses' frequency accordingly. First experiments showed that the application of this method results in a twelve-fold reduction of the width of the resonance frequencies' distribution. This improvement in determining qubit resonances is expected to lead to a significant improvement of the fidelity of multi-qubit conditional quantum gates.