We demonstrate correlations between non-twin beams of a frequency comb generated from a silicon nitride ring resonator optical parametric oscillator. The normalized correlation coefficient between these two modes is 0.997, corresponding to near-perfect correlations between the two beams.
This experimental work demonstrates multipartite quantum correlation in bright frequency combs out of a microresonator integrated on silicon nitride operating above its oscillation threshold. Multipartite features, going beyond so far reported two-mode correlation, naturally arise due to a cascade of nonlinear optical processes, making a single-color laser pump sufficient to initiate their generation. Our results show the transition from two-mode to multipartite correlation, witnessed by noise reductions as low as − 2.5 dB and − 2 dB , respectively, compared to corresponding classical levels. A constant of the movement of the nonlinear interaction Hamiltonian is identified and used to asses the multipartite behavior. Reported demonstrations pave the way to next generation on-chip multipartite sources for quantum technologies applications.
Multimode nonclassical states of light are an essential resource in quantum computation with continuous variables, for example, in cluster state computation. We report in this Letter the first experimental evidence of a multimode nonclassical frequency comb in a femtosecond synchronously pumped optical parametric oscillator. In addition to a global reduction of its quantum intensity fluctuations, the system features quantum correlations between different parts of its frequency spectrum. This allows us to show that the frequency comb is composed of several uncorrelated eigenmodes having specific spectral shapes, two of them at least being squeezed, and to characterize their spectral shapes.
Our work shows the existence of multipartite quantum correlations in bright frequency combs at the output of a microresonator integrated on silicon nitride platform. Multipartite features go beyond so far reported two-mode correlation and naturally arise due to a cascade of non-linear optical processes that, contrarily to other common experimental configurations, can be initiated by a single-color laser pump. We experimentally illustrate this behaviour by detecting the quantum correlation on the intensity noise spectra of up to 4 bright modes. Presented results, as well as the theoretical and experimental tools dedicated to their measurement, open the way to the exploitation of frequency combs for future quantum technology applications in continuous variable multipartite quantum photonics