Regular Article – Quantum Optics
The Hong–Ou–Mandel experiment: from photon indistinguishability to continuous-variable quantum computing
Departamento de Óptica, Facultad de Física, Universidad Complutense, 28040, Madrid, Spain
2 Université Paris Cité, CNRS, Laboratoire Matériaux et Phénomènes Quantiques, 75013, Paris, France
3 Univ. Paris-Sud 11, Institut de Sciences Moléculaires d’Orsay (CNRS), Bâtiment 350–Campus d’Orsay, 91405, Orsay Cedex, France
Accepted: 6 October 2022
Published online: 21 October 2022
We extensively discuss the Hong–Ou–Mandel experiment by taking an original phase-space-based perspective. For this, we analyze time and frequency variables as quantum continuous variables in perfect analogy with position and momentum of massive particles or with the electromagnetic field’s quadratures. We discuss how this experiment can be used to directly measure the time-frequency Wigner function and implement logical gates in these variables. We also briefly discuss the quantum/classical aspects of this experiment providing a general expression for intensity correlations that make explicit the differences between a classical Hong–Ou–Mandel-like dip and a quantum one. Throughout the manuscript, we will often focus and refer to a particular system based on AlGaAs waveguides emitting photon pairs via spontaneous parametric down conversion, but our results can be extended to other analogous experimental systems and to various degrees of freedom.
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