Heidelberg 2015 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 67: Quantum Information: Quantum Communication II
Q 67.6: Talk
Friday, March 27, 2015, 12:15–12:30, K/HS1
Sub-µs spin state detection of single trapped atoms for a loophole-free test of Bell’s inequality — •Norbert Ortegel1, Kai Redeker1, Daniel Burchardt1, Robert Garthoff1, Wenjamin Rosenfeld1,2, and Harald Weinfurter1,2 — 1Ludwig-Maximilians-Universität, München — 2Max-Planck Institut für Quantenoptik, Garching
We plan a test of Bell’s inequality with the detection and the locality loophole closed simultaneously in a single experiment. It consists of analyzing the Zeeman spin states of two 87Rb-atoms in the 5S1/2,F=1 ground state separated by 400m. Using entanglement swapping we create heralded entanglement between the atoms which allows closing the detection loophole.
To close the locality loophole we implemented an ultra-fast readout of the trapped atoms based on Zeeman-state selective ionization and subsequent detection of the ionization fragments with two channel electron multipliers (CEMs). Photo-ionization is done by Zeeman-state dependent excitation to 5P1/2,F=1 at 795nm and subsequent ionization at 450nm, where the polarization of the first exciting laser pulse determines the measurement basis of the readout.
We achieve a combined probabilty to detect the ion OR the electron from the ionization of a single atom of above 98%. This enables a fidelity for the state readout of 95%, mainly limited by off-resonant excitation to 5P1/2,F=2 during the photo-ionization. Including random setting of the measurement basis the overall duration of the readout is below 1µs.