Heidelberg 2015 – scientific programme

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A: Fachverband Atomphysik

A 31: Ultracold Atoms: Trapping and Cooling I (with Q)

A 31.1: Group Report

Thursday, March 26, 2015, 11:00–11:30, P/H2

Isospaced ion crystals and fault-tolerant Hahn-Ramsey interferometry — •Michael Johanning¹, Timm F. Gloger¹, Peter Kaufmann¹, Delia Kaufmann¹, Thomas Collath¹, M. Tanveer Baig¹, Nikolay V. Vitanov², and Christof Wunderlich¹ — ¹Faculty of Science and Technology, Department of Physics, University of Siegen, Walter Flex Str. 3, 57072 Siegen, Germany — ²Department of Physics, St Kliment Ohridski University of Sofia, 5 James Bourchier blvd, 1164 Sofia, Bulgaria

We describe the static and dynamic properties of strings of ions stored in segmented electrodynamical Paul traps with a uniform ion separation achieved by an anharmonic effective potential generated by suitable voltages applied to segmented dc electrodes or by appropriate electrode shaping. We find expressions for the desired potential and calculate normal modes and the effective spin coupling when the ion string is exposed to a magnetic gradient. The effect on the radial confinement and the transition of the equidistant linear chain to an almost equidistant zigzag are investigated.

In the second part, a scheme for efficient correction of driving field frequency drifts in Ramsey interferometry is presented. The two near-resonant π/2 pulses of duration T used in the traditional Ramsey setup are supplemented with an additional refocussing pulse of duration 2T and opposite detuning. We demonstrate the validity of the concept by comparing experimental results from plain Ramsey and Hahn-Ramsey measurements, obtained from microwave spectroscopy on ¹⁷¹Yb⁺ ions in a segmented linear Paul trap.