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Q: Fachverband Quantenoptik und Photonik

Q 51: Quantum Optical Correlations

Q 51.6: Talk

Thursday, March 14, 2024, 16:00–16:15, HS 1199

Multi-particle Hong-Ou-Mandel interference with Ultracold Atoms — •Martin Quensen, Mareike Hetzel, and Carsten Klempt — Institut für Quantenoptik, Leibniz Universität Hannover, Welfengarten 1, D-30167 Hannover, Germany

Two photons, coupled by a 50:50 beamsplitter, always exit at the same output port. This effect was first observed in 1987 by Hong, Ou and Mandel and lies at the heart of quantum optics, as it describes the interference of single, indistinguishable bosons.

Here, we demonstrate this effect with massive particles instead of photons, and extend it to the interference of up to eight atoms at once. To achieve this, we employ spin-changing collisions in a Bose-Einstein condensate of Rb-87 and generate coherent superpositions of multiple twin-atom pairs. A dynamic, low-noise microwave source realizes the 50:50 beamsplitter-like coupling via Rabi oscillations. We use an optical-molasses-based detection setup to count the number of atoms in the output ports with single-atom accuracy.

The observation of the Hong-Ou-Mandel effect in our setup paves the way for the generation and analysis of entangled quantum states of massive particles with increasing fidelity and atom number. The concepts can be employed for realizing Heisenberg-limited atom interferometry with mesoscopic states of matter.

Keywords: entanglement; non-classical states of matter; number resolved detection; foundations of quantum optics; Bose-Einstein condensate