Hannover 2013 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 53: Quantum information: Atoms and ions IV

Q 53.5: Vortrag

Donnerstag, 21. März 2013, 15:15–15:30, A 310

Microwave sideband cooling of trapped ions using a static magnetic gradient — •Andrés F. Varón, Benedikt Scharfenberger, Christian Piltz, Anastasiya Khromova, and Christof Wunderlich — Universität Siegen, NT Fakultät, Department Physik, 57068 Siegen, Germany

We report on microwave sideband cooling of trapped ¹⁷¹Yb⁺ ions. Different to laser cooling, microwave sideband cooling requires an additional mechanism that allows to couple internal states of a trapped ion with its vibrational states. This is done in the presence of a static magnetic field gradient created by two permanent magnets. Cooling is achieved by repetitions of the following two steps: First, microwave radiation, tuned to the red sideband of the hyperfine transition F=0 ↔ F=1 in the electronic ground state S_1/2 of ¹⁷¹Yb⁺, excites the ion reducing the phonon number by one. Second, laser light exciting the S_1/2, F=1 ↔ P_1/2, F=1 dipole allowed resonance pumps the ion back to the initial F=0 state but with a phonon less. The trap is characterized by an axial trapping frequency of 121 kHz. We systematically measure the final ion temperature for different microwave and laser intensities. For the optimized set of parameters we show a reduction of more than one order of magnitude on the mean phonon occupation number from ⟨ n ⟩ = 176 ± 30 to ⟨ n ⟩ = 4 ± 4 achieving temperatures close to the ground state.