Quantum frequency synchronization of distant clock oscillators

We propose the protocol for noise-resilient frequency synchronization (syntonization) of distant clocks’ local oscillators through a distributed quantum network. The syntonization is performed in two steps; First, we identify the node undergoing the systematic shift along with a coarse estimate of the shift. Second step provides the precise syntonization at the affected node, which involves optimal utilization of the available resources for this node. The protocol requires no prior shared phase reference because no quantum operation is performed at the affected node. Furthermore, based on the presence or absence of quantum noise, the nodes are categorized as leaf or branch nodes, respectively. This categorization and the distributed architecture allow the integration of new nodes directly through existing branch nodes. We show that even in the presence of quantum noise, the protocol provides optimal trade-off between accuracy and precision in the syntonization.