Towards global time distribution via satellite-based sources of entangled photons
Stav Haldar, Ivan Agullo, Anthony J. Brady, Antı́a Lamas-Linares, W. Cyrus Proctor, James E. Troupe
Abstract
We propose a satellite-based scheme to perform clock synchronization between ground stations spread across the globe using quantum resources. We refer to this as a quantum clock synchronization (QCS) network. Through detailed numerical simulations, we assess the feasibility and capabilities of a near-term implementation of this scheme. We consider a small constellation of satellites equipped only with modest resources. These include quantum devices such as spontaneous parametric down conversion sources, avalanche photodetectors, and moderately stable on-board clocks such as chip-scale atomic clocks. In our simulations, the various performance parameters describing the hardware have been chosen such that they are either already commercially available or require only moderate advances. We conclude that with such a scheme, establishing a global network of ground-based clocks synchronized to subnanosecond level (up to a few picoseconds) of precision would be feasible. Such QCS satellite constellations would form the infrastructure for a future quantum network, able to serve as a globally accessible entanglement resource. At the same time, our clock synchronization protocol provides the subnanosecond level synchronization required for many quantum networking protocols, and thus can be seen as adding an extra layer of utility to quantum technologies in the space domain designed for other purposes.