Global Time Distribution via Satellite-Based Sources of Entangled Photons

TL;DR

This paper proposes a satellite-based quantum clock synchronization network using modest quantum devices, demonstrating through simulations that sub-nanosecond precision is achievable for global ground clock synchronization.

Contribution

It introduces a feasible satellite-based quantum clock synchronization scheme utilizing commercially available hardware for global time distribution.

Findings

Global synchronization to sub-nanosecond precision is feasible.

A small constellation of nanosatellites can establish a quantum clock network.

The scheme supports quantum networking protocols requiring high-precision timing.

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 nanosatellites equipped only with modest resources. These include quantum devices such as spontaneous parametric down conversion (SPDC) sources, avalanche photo-detectors (APDs), and moderately stable on-board clocks such as chip scale atomic clocks (CSACs). 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 sub-nanosecond 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 sub-nanosecond 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.