Entangled Photon Interferometer for Satellite Clock Synchronization

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Solution Overview

Problem

Satellite constellations face challenges in precisely synchronizing atomic clocks due to unknown relative separations, which affects the synchronization of time and frequency information used in communication and navigation systems.

Innovation Solution

A dynamic optical interferometer locking system using entangled photons, which includes an optical source generating twin photons, emitters/receivers for remote reflectors, a mode combiner, coarse and fine adjusters, and photodetectors to synchronize optical path lengths, allowing for precise synchronization of clocks without determining individual flight times.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If interferometric methods are used to establish relative separations of satellites, then clock synchronization precision is improved, but the system requires known relative separations which are not available in satellite constellations

Engineering Contradiction:
Improveclock synchronization precisionVSAvoidsystem configuration complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces an optical interferometer as an intermediary device that enables precise measurement of relative satellite separations without requiring prior knowledge of these separations. The interferometer uses entangled photon pairs to create interference patterns that encode distance information, allowing the system to both measure and synchronize clocks simultaneously rather than requiring pre-established geometric knowledge

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system changes the measurement parameter from requiring known spatial coordinates to measuring optical path length differences directly through interference. By using entangled photons and measuring the phase difference in interference patterns, the system transforms the problem from one requiring positional knowledge to one that directly measures the relevant parameter (optical path difference) for clock synchronization

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If the optical path lengths are not precisely equalized, then the system is simpler to operate, but the clock synchronization precision deteriorates

Engineering Contradiction:
Improvetime base synchronization precisionVSAvoidoptical path adjustment complexity
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The patent implements a feedback control system where the interferometer continuously monitors the optical path length difference between satellite links and automatically adjusts path lengths to maintain equality. The interference signal provides real-time feedback on path differences, and control mechanisms adjust optical path lengths to keep the interferometer locked, ensuring continuous precise synchronization without manual intervention

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The interferometer system is designed to self-correct optical path length differences through its inherent interference measurement capability. When path lengths become unequal, the interference pattern changes, triggering automatic adjustment mechanisms that restore path equality without external control, making the system self-regulating and easy to operate

Inventive Principle:
Principle #25Self-service

3Reliability

If individual flight times are measured to synchronize clocks, then synchronization precision is improved, but the system becomes vulnerable to single-point attacks and less adaptable

Engineering Contradiction:
Improveresilience to attacksVSAvoidtime synchronization precision
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent segments the time synchronization measurement into two independent components: the round-trip time measurement (which is vulnerable) and the interferometric optical path difference measurement (which is secure). By using entangled photons and measuring interference patterns at the source satellite rather than relying on individual flight time reports from remote satellites, the system eliminates the vulnerability to single-point attacks while maintaining femtosecond-level precision

Inventive Principle:
Principle #1Segmentation

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

Enables precise synchronization of atomic clocks across satellite constellations, achieving femtosecond-precise time bases and improving signal-to-noise ratios in imaging and navigation systems, while being resilient to single-point attacks and adaptable for various mission profiles.

Implementation Method 1

an optical source for generating a pair of simultaneously produced photons

Methodology Applied
Scientific EffectSpontaneous parametric down-conversion:

Implementation Method 2

interacting the reflected first photon and the delayed second photon to produce HOM interference

Methodology Applied
Scientific EffectHong-Ou-Mandel interference: Interference

Implementation Method 3

a plurality of photodetectors that detect photons from the first output port and photons from the second output port

Methodology Applied
Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentEP3943877B1Dynamic optical interferometer locking using entangled photons
Publication Date: 2023.08.09 HONEYWELL INTERNATIONAL INC
  • EP3943877B1 patent drawingFigure 1
  • EP3943877B1 patent drawingFigure 2
  • EP3943877B1 patent drawingFigure 3

AI summary

Systems and methods for dynamic optical interferometer locking using entangled photons are provided. In certain embodiments, a system includes an optical source for generating a pair of photons. Also, the system includes first and second emitter/receivers that emit first and second photons towards first and second remote reflectors and receive reflected first and second photons along first and second optical paths. Additionally, the system includes a mode combiner for combining the reflected first photon and second photon into a first and second output port. Moreover, the system includes a coarse adjuster that performs coarse adjustments and a fine adjuster that performs fine adjustments to the first and second optical paths. Further, the system includes a plurality of photodetectors that detect photons from the first and second output ports. Additionally, the system includes a processor that controls the coarse and fine adjustments based on received signals from the photodetectors.