Quantum Information Processing With Frequency-Comb Qudits

Classical optical frequency combs have revolutionized a myriad of fields, from optical spectroscopy and optical clocks to arbitrary microwave synthesis and lightwave communication. Capitalizing on the inherent robustness and high dimensionality of this mature optical platform, their nonclassical counterparts, so-called "quantum frequency combs," have recently begun to display significant promise for fiber-compatible quantum information processing (QIP) and quantum networks. In this review, the basic theory and experiments of frequency-bin QIP, as well as perspectives on opportunities for continued advances, will be covered. Particular emphasis is placed on the recent demonstration of the quantum frequency processor (QFP), a photonic device based on electro-optic modulation and Fourier-transform pulse shaping that is capable of realizing high-fidelity quantum frequency gates in a parallel, low-noise fashion.