New paper published in Phys. Rev. Research: 『Harnessing hybrid frequency-entangled qudits through quantum interference』

Our paper has been published in Phys. Rev. Research.

In this work, we present an HD frequency-domain entangled state, the hybrid frequency-entangled qudit (HFEQ), generated via Hong-Ou-Mandel (HOM) interference, exhibiting both discrete-variable (DV) and continuous-variable (CV) characteristics in the frequency domain. By tuning HOM interference, we generate and control HFEQs with dimensions 𝐷=5,7,9, and 11, confirming their DV nature. Franson interferometry verifies global frequency correlations with a visibility of 97.6±0.6% and CV entanglement within individual frequency modes with a visibility exceeding 95%. Furthermore, based on the developed theoretical model, the generated HFEQs exhibit a Schmidt number that exceeds the upper bound 𝐷 of conventional frequency-entangled qudits, certifying additional entanglement inherent to the hybrid structure. Our findings provide deeper insight into the physical nature of frequency-entangled qudits generated by quantum interference and introduce a resource for HD time-frequency quantum information processing.

DOI: https://doi.org/10.1103/99qy-y833