LEO Clock Synchronization with Entangled Light

TL;DR

This paper demonstrates that entangled light can improve clock synchronization over lossy satellite channels, surpassing classical limits and single-mode squeezing, with practical implications for space-based precision timing.

Contribution

It shows that entanglement provides a quantum advantage in satellite clock synchronization despite channel losses, offering a new approach for space-based sensing.

Findings

Entanglement enables recoverability over asymmetric lossy channels.

Quantum advantage over classical and single-mode squeezing methods.

Improved synchronization performance in space-based applications.

Abstract

Precision navigation and timing, very-long-baseline interferometry, next-generation communication, sensing, and tests of fundamental physics all require a highly synchronized network of clocks. With the advance of highly-accurate optical atomic clocks, the precision requirements for synchronization are reaching the limits of classical physics (i.e. the standard quantum limit, SQL). Efficiently overcoming the SQL to reach the fundamental Heisenberg limit can be achieved via the use of squeezed or entangled light. Although approaches to the Heisenberg limit are well understood in theory, a practical implementation, such as in space-based platforms, requires that the advantage outweighs the added costs and complexity. Here, we focus on the question: can entanglement yield a quantum advantage in clock synchronization over lossy satellite-to-satellite channels? We answer in the affirmative, showing that the redundancy afforded by the two-mode nature of entanglement allows recoverability even over asymmetrically lossy channels. We further show this recoverability is an improvement over single-mode squeezing sensing, thereby illustrating a new complexity-performance trade-off for space-based sensing applications.