摘要
Precision time synchronization underpins a wide array of modern technologies,from relativistic geodesy to distributed quantum networks.Quantum two-way time transfer(QTWTT),which harnesses the tight temporal correlations of energy-time entangled photon pairs,has achieved remarkable sub-picosecond stability[1]while offering intrinsic security against timing attacks[2].Yet,the quantum nocloning theorem—prohibiting the amplification of quantum states—imposes a fundamental barrier to extending QTWTT over long distances due to inevitable signal loss in fiber-optic channels[3].In a recent study published in Science China Physics,Mechanics&Astronomy,a cascaded Q-TWTT architecture is presented that bypasses this challenge by using relay stations to generate and distribute entangled photon pairs[4].
