In an exciting collaboration between experiment and theory, we revisit one of the staples of quantum optics: the Hong-Ou-Mandel effect. We show that when a quantum emitter produces a superposition of zero and one photon, the outcome of well-established quantum interference experiments changes and entanglement phenomena arise. This study not only showcases the rich quantum physics associated with photon-number coherence, but we also anticipate it can open up interesting possibilities for quantum information processing with photons.
I. Maillette de Buy Wenniger, S. C. Wein, D. Fioretto, S. E. Thomas, C. Antón-Solanas, A. Lemaître, I. Sagnes, A. Harouri, N. Belabas, N. Somaschi, P. Hilaire, J. Senellart, and P. Senellart, “Quantum interferences and gates with emitter-based coherent photon sources,” Optica Quantum 2, 404-412 (2024)