Co-Propagating Optical Clock Pulses for Quantum Photon Synchronization

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Solution Overview

Problem

Achieving sub-picosecond synchronization of photonic qubits in multi-photon operations across quantum networks is challenging, especially in free-space links with mobile platforms, due to path delay fluctuations from atmospheric effects and platform motion, which existing clock synchronization protocols cannot adequately address.

Innovation Solution

Generating optical clock pulses that co-propagate with photons over quantum channels, ensuring similar path delay fluctuations and allowing for picosecond or sub-picosecond timing synchronization by canceling out path delay fluctuations through identical path delays experienced by both clock pulses and photons, thereby enabling precise synchronization for multi-photon operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If standard clock synchronization protocols (GPS, T2L2) are used, then clock synchronization is achieved, but the accuracy is insufficient (ten-nanosecond to one hundred picosecond accuracy) for multi-photon operations requiring picosecond or sub-picosecond accuracy

Engineering Contradiction:
Improvephoton arrival time synchronization accuracyVSAvoidsynchronization reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent combines the clock synchronization function with the quantum communication channel by co-propagating optical clock pulses together with quantum photons through the same free-space atmospheric path. This merging allows both signals to experience identical path delay fluctuations from atmospheric effects and platform motion, automatically canceling out these errors and achieving picosecond or sub-picosecond synchronization accuracy without requiring separate high-precision timing systems.

Inventive Principle:
Principle #5Merging (Combining)

2Measurement precision

If active link monitoring and feedback loops are employed to correct atmospheric effects and platform motion, then path delay fluctuations are compensated, but system complexity and link latency increase

Engineering Contradiction:
Improvepath delay compensation accuracyVSAvoidfeedback system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent converts the harmful effect of atmospheric turbulence and platform motion into a beneficial common-mode signal by having both the clock pulses and quantum photons traverse the same atmospheric path. The path delay fluctuations affect both signals identically, transforming what would be separate error sources into a correlated signal that automatically cancels out during synchronization, eliminating the need for complex active compensation systems.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Adaptability or versatility

If separate clock synchronization and quantum communication channels are used, then channel independence is maintained, but path delay fluctuations from atmospheric effects cause synchronization errors

Engineering Contradiction:
Improvechannel independenceVSAvoidsynchronization accuracy
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent merges the clock synchronization function with the quantum communication channel by co-propagating optical clock pulses together with quantum photons through the same free-space atmospheric path. This merging allows both signals to experience identical path delay fluctuations from atmospheric effects and platform motion, automatically canceling out these errors and achieving picosecond or sub-picosecond synchronization accuracy without requiring separate high-precision timing systems.

Inventive Principle:
Principle #5Merging (Combining)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach allows for sub-picosecond timing synchronization of photons, eliminating the need for complex feedback systems and achieving accurate multi-photon operations even in dynamic environments, using commercially available telecommunications equipment.

Implementation Method 1

transmitting, from the first network node, the combined signal over a first quantum channel in which the optical clock pulses co-propagate with the first photons

Methodology Applied
Scientific EffectCo-propagation:

Implementation Method 2

path delay fluctuations due to atmospheric effects

Methodology Applied
Scientific EffectAtmospheric effects:

Implementation Method 3

the optical clock pulse is amplified and used to pump Spontaneous Parametric Down Conversion (SPDC) in a nonlinear crystal to produce entangled pairs of photons

Methodology Applied
Scientific EffectSpontaneous Parametric Down Conversion:

Implementation Method 4

generating pump pulses by changing a frequency of the optical clock pulses from a first frequency to a second different frequency

Methodology Applied
Scientific EffectSecond Harmonic Generation: Second Harmonic Generation

Data Source

PatentEP4175202A1Systems and methods for synchronization of photons over quantum channels with co-propagating clock pulses
Publication Date: 2023.05.03 EAGLE TECHNOLOGY LLC
  • EP4175202A1 patent drawingFigure 1
  • EP4175202A1 patent drawingFigure 2
  • EP4175202A1 patent drawingFigure 3

AI summary

Systems and methods for operating a quantum network system. The methods comprise, by a network node: generating optical clock pulses and photons using the optical clock pulses; generating a combined signal by combining the optical clock pulses with at least some of the photons such that a consistent temporal offset exits between the optical clock pulses and the first photons and/or a wave function of each photon at least partially overlaps an envelope of a respective one of the optical clock pulses; and transmitting the combined signal over a first quantum channel in which the optical clock pulses co-propagate with the photons.