Global quantum clock synchronization network using a constellation of satellites - A precursor to the Quantum Internet

We propose the near-term implementation of a hybrid quantum network of satellite and ground based clocks with the ability to implement a quantum clock synchronization (QCS) protocol to the picosecond level. We simulate the sync outcomes for cities across the globe using a minimalistic constellation of satellites, low-cost entanglement sources, portable atomic clocks, and avalanche detectors. Such a QCS network will form the basis of future quantum networks like the Quantum Internet, distributed quantum sensing and Quantum GPS. In contrast to classical techniques, QCS does not require an apriori knowledge of time of travel between two parties, instead both time of travel and clock offset can be extracted independently. It utilizes the tight time-correlations between entangled photons and the information transfer efficiency gains offered by optical communication using single photon detection over radio frequency (RF) based classical communication. Using the polarization correlations, the QCS protocol also has quantum security. Picosecond level sync outcomes can be achieved with < 100 exchanged photons making the protocol ideal for Deep Space Quantum Links (DSQLs). The use of free space optical communication and fast-moving LEO satellites increases the network size considerably.