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Q: Fachverband Quantenoptik und Photonik

Q 60: Quantum Information II

Q 60.9: Poster

Thursday, March 17, 2022, 16:30–18:30, P

A nondestructive Bell-state measurement on two distant atomic qubits — •Matthias Seubert, Stephan Welte, Philip Thomas, Lukas Hartung, Severin Daiss, Stefan Langenfeld, Oliver Morin, Emanuele Distante, and Gerhard Rempe — Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, 85748 Garching, Germany

To exploit the full capability of quantum networks, it is necessary to develop schemes to generate, store and detect entanglement. Most of the detection techniques presented so far, are impaired by being local, destructive or not complete.

Here, we describe a complete and nondestructive entanglement detection scheme on two spatially separated network nodes. Each node is realized by a single ⁸⁷Rb atom stored in a strong coupling optical resonator connected by a 60 m optical fiber link. At first, an ancillary photon is consecutively reflected on each resonator, performing atom-photon gates at each reflection [1]. Repeating this sequence with a second ancillary photon, any initial two atom state is projected onto one of the four Bell-states [2]. The generated state is identified by polarization measurements of both photons. As this scheme does not destroy the quantum states, it can be utilized in future applications to preserve entanglement from dephasing by repetitive measurements using the quantum Zeno effect.

[1] Andreas Reiserer et al., Nature 508, 237 (2014)

[2] Stephan Welte et al., Nature Photonics 15, 504-509 (2021)