Using quantum entanglement to secure ground-to-satellite timing

From mobile phones and banking systems to aircraft, ships and emergency services, much of modern life relies on precise timing signals from satellites. Known as the Global Navigation Satellite System (GNSS), satellites carrying atomic clocks transmit time-stamped signals to receivers on Earth. The Global Positioning System (GPS) is the best-known GNSS in Australia and the United States, but it is only one of several systems used globally.