High-resolution measurement of spectral quantum correlations in the telecommunication band

We present an automated and stable method to measure an arbitrary portion of the joint spectral intensity of quantum photonic devices with an unprecedented resolution of 10 GHz in the telecommunication band. The method is applied to a 20 cm chalcogenide As2S3 fiber that generates correlated photons via spontaneous four-wave mixing. Good qualitative agreement between our measurements and an idealized theoretical model is obtained. The entanglement present in the system is extracted via a Schmidt decomposition where the reduction in the Schmidt number compared to that calculated via the model is attributed to the high amount of spontaneous Raman scattered noise photons present in chalcogenide fiber.