Why Sub-Nanosecond Timing is the Missing Link for Distributed Quantum Computing and QKD

For quantum scientists and researchers, the challenge is no longer just about generating qubits; it is about scaling them. Whether you are working on distributed quantum computing, Quantum Key Distribution (QKD), or long-distance entanglement, you face the same fundamental hurdle: synchronization.

To entangle distant quantum nodes, photons must arrive within a fraction of their coherence time—often requiring synchronization accuracy below 10 picoseconds. Standard NTP or even basic PTP solutions simply cannot meet these requirements.

At Telnet Networks, we bridge the gap between theoretical physics and deployed infrastructure. Today, we are highlighting White Rabbit (WR)—the Ethernet-based timing technology born at CERN—and how our partners Safran and Timebeat are productizing this technology to power the next generation of quantum research.

Why White Rabbit?

Originally developed to synchronize accelerators at CERN, White Rabbit combines the IEEE 1588 Precision Time Protocol (PTP) with Synchronous Ethernet (SyncE) to achieve sub-nanosecond accuracy and picosecond-level precision over standard optical fiber,.

For the quantum sector, WR offers three critical advantages:

• Determinism: It actively compensates for fiber propagation delays and environmental changes (like temperature shifts), ensuring stability over distances ranging from a single lab campus to metro links exceeding 80km.
• Scalability: Unlike point-to-point clock cabling, WR scales to thousands of nodes using standard Ethernet switches, allowing you to synchronize heterogeneous equipment.
• Coexistence: Classical WR timing signals can co-propagate with quantum signals on the same fiber using Wavelength Division Multiplexing (WDM), economizing expensive fiber leases.

Solution Spotlight: Safran Navigation & Timing

Safran (formerly Orolia) has been a pioneer in industrializing White Rabbit. Their solutions are particularly relevant for researchers needing integrated instrumentation control.

White Rabbit Z16 & WR-ZEN

For the network layer, Safran’s White Rabbit Z16 acts as the backbone, offering 16 optical ports to distribute time across your facility. For end-points, the WR-ZEN boards provide the flexibility to output precise PPS and 10MHz signals to legacy lab equipment that isn’t natively WR-compatible.

Recent Innovation: CERN recently partnered with Qunnect and Single Quantum to launch a new quantum networking lab, using Safran-compatible White Rabbit technology to achieve sub-nanosecond alignment for entanglement distribution.

The Quantum Instrumentation Control Kit (QICK)

If you are building superconducting quantum hardware or quantum sensors, you should know about QICK. Developed in partnership with Fermilab, QICK is an open-source FPGA-based control and readout system manufactured by Safran.

What it does: It provides direct synthesis of control pulses (up to 6 GHz) and ultra-low noise readout.

The WR Connection: It features built-in White Rabbit support, allowing multiple QICK boards to be synchronized to sub-nanosecond precision. This enables the scaling of qubit control across multiple chassis without losing phase coherence.

Solution Spotlight: Timebeat

Timebeat brings a focus on open standards and commercial accessibility, making it easier to deploy CERN-grade timing in enterprise and data center environments. Their ecosystem is built to be “plug-and-play” for researchers moving from proof-of-concept to pilot networks.

Open Time Node WR

For labs managing a mix of modern and legacy instrumentation, the Open Time Node WR serves as a critical bridge.

• What it does: It extends your optical timing network with four independent White Rabbit ports while simultaneously providing ten high-quality frequency outputs.

• Why it matters: This node allows you to synchronize legacy equipment (such as oscilloscopes or signal generators requiring 10MHz inputs) to the same sub-nanosecond optical backbone as your quantum devices, ensuring consistent timing across your entire experimental topology

Open Time Switch WR

High-density connectivity is essential for data-center-scale quantum experiments. Timebeat’s Open Time Switch WR offers 24 ports (including 8x 10GbE ports), allowing for high-bandwidth data and timing distribution in a single rack unit.

OEM-Ready Mezzanine Boards

For scientists building custom detectors or proprietary quantum modems, Timebeat offers White Rabbit Mezzanine Boards.

• Application: These compact modules allow you to embed sub-nanosecond timing directly into your custom PCB designs without engineering the timing circuit from scratch.

• Benefit: Instantly make your custom scientific instruments White Rabbit compatible and interoperable with the wider network.

Software-Defined Visibility

Timebeat emphasizes visibility. Their platform allows researchers to monitor clock stability and sync performance in real-time, which is critical when debugging why a Bell-state measurement might have failed due to timing jitter

Applications in the Field

Quantum Networking (QKD): White Rabbit is currently being used in testbeds like the DCQnet (Washington, DC) to synchronize nodes for entanglement swapping. NIST researchers have demonstrated that WR signals can coexist with quantum channels even over 100km of fiber.

Distributed Quantum Computing: By synchronizing independent QPUs, WR enables the “interconnects” required to scale computing power beyond a single refrigerator.

Radio Astronomy: Facilities like the Square Kilometer Array (SKA) utilize WR to synchronize telescopes across vast deserts, acting as a single giant sensor.

Ready to Synchronize Your Lab?

At Telnet Networks, we are Canadian experts in mission-critical network infrastructure. We can help you design a timing architecture that leverages the best of Safran and Timebeat to ensure your quantum experiments are never limited by the speed of your clock.

Contact our team today to discuss your synchronization requirements for your quantum projects.