Fig. 1: Experimental setup.

a Generation of high-dimensional frequency-entangled qudits through b Hong-Ou-Mandel interference. c Observation of frequency anti-correlations with a monochromator. Assisted by the elimination of spatially bunched photons d, HOM interference of high dimensional entanglement is observed e. LD laser diode, PBS polarizing beam splitter, HWP half wave plate, DM dichroic mirror, TEC temperature controller, LP long pass filter, SMF single-mode fiber, BS beam splitter, MMF multi-mode fiber, POL polarizer.