TEP Seminar - Holger F. Hofmann

As  optical networks scale up, a wide variety of multi-photon entangled  states becomes available for applications in optical quantum computation, quantum communication and quantum metrology. Our group at Hiroshima University has been investigating new  protocols using the intrinsic nonlocality of optical modes based on the  phase coherence between separate components of the same waveform. Entanglement generation can then be described in  terms of a mode swap between two systems. We have used this method to  identify a nonlocal version of the Hong-Ou-Mandel effect, relating the  output correlations to orthogonal superpositions of the input modes of two photons. The mode-based analysis of  multi-photon interference makes the best possible use of our classical  intuition regarding the interference of waves and may help us to scale  up non-classical effects by converting familiar effects in multi-photon interferences involving only a few modes into nonlocal  correlations between spatially separated photon number distributions. 

[1] The non-local Hong-Ou-Mandel effect, Y. Kodama et al., arXiv:2604.10886 (2026).
[2] Entangled measurement for W states, G. Park et al., Sci. Adv. 11, eadx4180 (2025).
[3] Direct and efficient verification of entanglement between two multi-mode multi-photon systems, T. Kiyohara et al., Optica 7, 1517 (2020).