Bell inequality violation in frequency domain using 25 GHz frequency sideband modulation architecture

Since the pioneering work of A. Ekert, it has been known that entangled quantum states could be used for quantum key distribution (QKD). Using entangled photons could potentially allows the realization of key distribution protocols over distances greater than a few hundred kilometres, and allows security certification without a priori trust of the devices. Although practical QKD methods based on time-bin entanglement have seen significant development, it is only recently that frequency-bin entanglement has been investigated. In what follows, we report the performance of a new automated architecture based on 25 GHz frequency sideband modulation designed specifically for manipulation of frequency-bins, with potential applications such as QKD.