Eloi Descamps - The Hong-Ou-Mandel Interferometer:  From a simple measurement setup to advanced quantum metrology

The Hong-Ou-Mandel Interferometer:  From a simple measurement setup to advanced quantum metrology

This seminar, given by Eloi Descamps, will happend on 14 January 2026, at 13:0. It will take place in Room 25-26/105.

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Abstract

The Hong-Ou-Mandel (HOM) effect is one of the simplest and most striking manifestations of quantum interference: two indistinguishable photons entering a beam splitter always exit together. Despite its apparent simplicity, this effect plays a central role in quantum optics, from benchmarking single-photon sources to enabling remarkably precise parameter estimation with minimal resources. In this talk, I will revisit the HOM effect from a unifying perspective based on symmetry under exchange of spatial modes. I will show how this symmetry viewpoint not only clarifies the origin of photon bunching in the standard two-photon experiment, but also provides a powerful framework to generalize HOM interference to arbitrary input states and to multi-mode interferometers, naturally described by discrete Fourier transform networks. Beyond conceptual insight, this approach has direct implications for quantum metrology. The symmetry properties of the input states determine their sensitivity to physical parameters, allowing explicit precision bounds to be derived and guiding the design of efficient, quantum-enhanced sensing schemes. By focusing on symmetry as the organizing principle, the HOM effect emerges as a versatile and extensible tool for both fundamental studies of quantum interference and practical applications in precision measurement.