UltrafaSt Post-Selection Free Time-Bin Entanglement on a Thin Film Lithium Niobate Photonic Chip

The distribution of entangled photons between remote parties is fundamental for quantum communication protocols such as quantum teleportation and quantum key distribution (QKD). Among the various encoding schemes, time-bin entanglement is particularly promising as it ensures reliable long-distance communication for both optical fibre and free-space channels. However, the practical utility of time bin entanglement is constrained by the post-selection loophole (PSL), which allows for the possibility of local hidden variable models [1]. Temporal post-selection also opens the door to attack schemes and demands high temporal resolution. Initial efforts to close the PSL employed hyperentangled states combining polarization and time-bin degrees of freedom [2]. Later, Vedovato et al. used active switching to remove the need for post-selection [3], and an integrated “hug” scheme was used to demonstrate PSL-free certification through a phase-stabilized optical link [4].