Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

A quantum-assisted master clock in the sky: global synchronization from satellites at sub-nanosecond precision

Stav Haldar, Sage Ducoing, Iván Agulló, James E. Troupe

Published Feb 5, 2024• 0 citations
Publisher

Abstract

Abstract This article develops a protocol to synchronize clocks on board a network of satellites equipped with quantum resources. We show that, in such a constellation, satellites reinforce each other's sync capabilities, forming a common clock that is more stable and precise than its constituents. We envision the resulting network as a master clock able to distribute time across the globe, providing the basis for a future quantum global navigation satellite system or a space-based quantum network. As an example of its capabilities, we show that a constellation of 50 satellites equipped with modest quantum resources, and distributed amongst 5 orbits at an altitude of 500 km, allows the synchronization of clocks spread across the globe at sub-nanosecond precision.

DOI
10.21203/rs.3.rs-3773766/v1

Related papers

A quantum-assisted master clock in the sky: global synchronization from satellites at sub-nanosecond precision

Sage Ducoing, Iván Agulló, James E. Troupe +1 more

This article develops a protocol to synchronize clocks on board a network of satellites equipped with quantum resources. We show that, in such a constellation, satellites reinforce each other's sync capabilities, forming a common clock that is more stable and precise than its constituents. We envision the resulting network as a master clock able to distribute time across the globe, providing the basis for a future quantum global navigation satellite system or a space-based quantum network. As an example of its capabilities, we show that a constellation of 50 satellites equipped with modest quantum resources, and distributed amongst 5 orbits at an altitude of 500 km, allows the synchronization of clocks spread across the globe at sub-nanosecond precision.

arXiv:2311.11155•Nov 18, 2023•0 citations

A quantum-assisted master clock in the sky – sub-nanosecond quantum clock synchronization at global scales

Sage Ducoing, Stav Haldar, James E. Troupe +1 more

We propose a quantum-assisted network of low-SWaP satellite-based clocks forming a master clock in the sky. Synchronization amongst satellites and between satellite-ground station pairs is done through a quantum clock synchronization protocol. This pro-vides continuous sub-nanosecond to picosecond precision over global scales (better than GPS).

Quantum 2.0 Conference and Exhibition•Jan 1, 2023•0 citations

Towards global time distribution via satellite-based sources of entangled photons

Stav Haldar, Iván Agulló, Anthony J. Brady +3 more

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.

arXiv:2209.15071•Physical Review A•Feb 21, 2023•19 citations

Quantum-assisted master clock in the sky: Global synchronization from satellites at subnanosecond precision

Sage Ducoing, Iván Agulló, James E. Troupe +1 more

The Global Positioning System (GPS) provides uninterrupted position and timing data across the globe with a precision of up to 40 ns, but is insufficient for advanced applications such as quantum communication, and is susceptible to jamming and spoofing attacks. This article introduces a protocol for synchronizing clocks using a constellation of satellites that relies on the exchange of entangled photons. Simulation shows that 50 low-Earth-orbit satellites bearing off-the-shelf atomic clocks can distribute time globally with a precision that is 2 to 4 orders of magnitude higher than that of GPS. Additionally, the use of entangled photons provides an extra layer of quantum security.

Physical Review Applied•Jan 23, 2025•1 citation

Satellite-mediated Quantum Clock Synchronization: Towards Precise Timing at a Global Scale

Sage Ducoing

Accurate timekeeping is essential for scientific and technological advancements, particularly in areas of communication, networking, navigation, and high precision measurements. While many methods of time resolution are already established using classical resources, they fail to combine high precision outcomes with large-scale implementations. Additionally, numerous quantum networking architectures using satellite-assisted methods have demonstrated quantum communication on scales exceeding ground-based methods. For these reasons, we propose the use of a time synchronization method by which pairs of highly time-correlated photons are exchanged between clocks on satellites and clocks on Earth, al- lowing users to reconstruct the time offsets between their clocks. This is known as Quantum Clock Synchronization (QCS). We analyze global time synchronization, via numerical simulation, using a network of satellites equipped with quantum resources, such as entangled photon sources (SPDC) and single photon detectors. We find that for satellites in low-earth orbits, a configuration of 50 evenly-space satellites provides constant visibility and sub-nanosecond time synchronization to any location on Earth. Due to practical constraints, clocks available for use on satellites are often of lesser quality than those available for ground use. However, by allowing the satellites in our network to synchronize among themselves, we overcome this limitation, forming a highly precise “master clock” capable of global, high precision time synchronization. We then examine the amount of quantum security provided by polarization-entangled photon sources as a potential way to protect an experimental implementation of QCS from attacks such as signal spoofing. To do this, we identify regions on Earth where Bell violations between exchanged entangled photons can ensure quantum security at various confidence vii levels. Combined with similar insights gained from determining the network scale of our QCS protocol at the single-link level, we demonstrate the potential for highly precise, global, and potentially quantum-secure clock synchronization. Finally, we modify our QCS protocol to support frequency, or tick-rate, offsets in addition to constant time offsets. We motivate this by presenting some relativistic effects that can introduce frequency differences between clocks in space and on Earth. Provided that relative velocities between clocks are corrected for, we identify constant and variable clock defects through numerical simulations.

Civil War Book Review•Dec 26, 2025•0 citations

Quantum Clock Synchronization for Future NASA Deep Space Quantum Links and Fundamental Science

James E. Troupe, Stav Haldar, Iván Agulló +1 more

The ability to measure, hold and distribute time with high precision and accuracy is a foundational capability for scientific exploration. Beyond fundamental science, time synchronization is an indispensable feature of public and private communication, navigation and ranging, and distributed sensing, amongst others technological applications. We propose the implementation of a quantum network of satellite- and ground-based clocks with the ability to implement Quantum Clock Synchronization to picosecond accuracy. Implementation of the proposed QCS network offers a double advantage: (1) a more accurate, robust, and secure time synchronization network for classical applications than currently possible, and (2) a resource to fulfill the much more stringent synchronization requirements of future quantum communication networks.

arXiv:2209.15122•Sep 29, 2022•8 citations
Abstract This article develops a protocol to synchronize clocks on board a network of satellites equipped with quantum resources. We show that, in such a constellation, satellites reinforce each other's sync capabilities, forming a common clock that is more stable and precise than its constituents. We envision the resulting network as a master clock able to distribute time across the globe, providing the basis for a future quantum global navigation satellite system or a space-based quantum network. As an example of its capabilities, we show that a constellation of 50 satellites equipped with modest quantum resources, and distributed amongst 5 orbits at an altitude of 500 km, allows the synchronization of clocks spread across the globe at sub-nanosecond precision.
This article develops a protocol to synchronize clocks on board a network of satellites equipped with quantum resources. We show that, in such a constellation, satellites reinforce each other's sync capabilities, forming a common clock that is more stable and precise than its constituents. We envision the resulting network as a master clock able to distribute time across the globe, providing the basis for a future quantum global navigation satellite system or a space-based quantum network. As an example of its capabilities, we show that a constellation of 50 satellites equipped with modest quantum resources, and distributed amongst 5 orbits at an altitude of 500 km, allows the synchronization of clocks spread across the globe at sub-nanosecond precision.
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.
The Global Positioning System (GPS) provides uninterrupted position and timing data across the globe with a precision of up to 40 ns, but is insufficient for advanced applications such as quantum communication, and is susceptible to jamming and spoofing attacks. This article introduces a protocol for synchronizing clocks using a constellation of satellites that relies on the exchange of entangled photons. Simulation shows that 50 low-Earth-orbit satellites bearing off-the-shelf atomic clocks can distribute time globally with a precision that is 2 to 4 orders of magnitude higher than that of GPS. Additionally, the use of entangled photons provides an extra layer of quantum security.
Accurate timekeeping is essential for scientific and technological advancements, particularly in areas of communication, networking, navigation, and high precision measurements. While many methods of time resolution are already established using classical resources, they fail to combine high precision outcomes with large-scale implementations. Additionally, numerous quantum networking architectures using satellite-assisted methods have demonstrated quantum communication on scales exceeding ground-based methods. For these reasons, we propose the use of a time synchronization method by which pairs of highly time-correlated photons are exchanged between clocks on satellites and clocks on Earth, al- lowing users to reconstruct the time offsets between their clocks. This is known as Quantum Clock Synchronization (QCS). We analyze global time synchronization, via numerical simulation, using a network of satellites equipped with quantum resources, such as entangled photon sources (SPDC) and single photon detectors. We find that for satellites in low-earth orbits, a configuration of 50 evenly-space satellites provides constant visibility and sub-nanosecond time synchronization to any location on Earth. Due to practical constraints, clocks available for use on satellites are often of lesser quality than those available for ground use. However, by allowing the satellites in our network to synchronize among themselves, we overcome this limitation, forming a highly precise “master clock” capable of global, high precision time synchronization. We then examine the amount of quantum security provided by polarization-entangled photon sources as a potential way to protect an experimental implementation of QCS from attacks such as signal spoofing. To do this, we identify regions on Earth where Bell violations between exchanged entangled photons can ensure quantum security at various confidence vii levels. Combined with similar insights gained from determining the network scale of our QCS protocol at the single-link level, we demonstrate the potential for highly precise, global, and potentially quantum-secure clock synchronization. Finally, we modify our QCS protocol to support frequency, or tick-rate, offsets in addition to constant time offsets. We motivate this by presenting some relativistic effects that can introduce frequency differences between clocks in space and on Earth. Provided that relative velocities between clocks are corrected for, we identify constant and variable clock defects through numerical simulations.
The ability to measure, hold and distribute time with high precision and accuracy is a foundational capability for scientific exploration. Beyond fundamental science, time synchronization is an indispensable feature of public and private communication, navigation and ranging, and distributed sensing, amongst others technological applications. We propose the implementation of a quantum network of satellite- and ground-based clocks with the ability to implement Quantum Clock Synchronization to picosecond accuracy. Implementation of the proposed QCS network offers a double advantage: (1) a more accurate, robust, and secure time synchronization network for classical applications than currently possible, and (2) a resource to fulfill the much more stringent synchronization requirements of future quantum communication networks.