Entangled Photon Spread-Spectrum Sensing for Covert Range Detection
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Solution Overview
Problem
Existing covert sensing and communication systems face challenges in achieving high precision without alerting adversaries, often compromising accuracy, and in communicating covertly without detection.
Innovation Solution
A system using quantum entanglement-assisted waveform coding to spread narrow-band signals over a broader frequency band, combined with phase conjugation and optical delay to enhance detection precision and create a covert communications channel, utilizing broadband light sources and entangled photons for covert sensing and communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If quantum entanglement-assisted waveform coding is used to spread narrow-band signal over frequency, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent uses an optical phase conjugator as an intermediary device to generate a phase-conjugated reference signal that automatically compensates for phase distortions. This intermediary component enables high-precision measurement without requiring complex digital signal processing algorithms, thereby resolving the contradiction between measurement precision and device complexity
Solution Approach 2:
The system transforms the narrow-band signal into a spread spectrum signal by modulating with pseudo-random codes, changing the frequency parameter distribution. This parameter transformation allows precise range estimation through correlation processing while the optical phase conjugation simplifies the overall system architecture compared to purely digital approaches
2Measurement precision
If broadband light source with large bandwidth is used, then sensitivity is improved, but detectability by adversaries increases
Solution Approach 1:
The patent applies local quality by using broadband light only in the specific spectral regions (C-band, S-band, or L-band) where atmospheric transmission is optimal and adversary detection is minimized. The system selectively utilizes portions of the broadband spectrum rather than uniformly across all frequencies, improving sensitivity while reducing detectability
Solution Approach 2:
The optical phase conjugator acts as an intermediary that enables the system to use broadband illumination for enhanced sensitivity while the phase-conjugated reference signal provides a coherent detection mechanism that maintains signal integrity. This allows sensitive detection without proportionally increasing the detectable signal strength
3Measurement precision
If optical phase conjugation is implemented, then accuracy is improved, but device complexity increases
Solution Approach 1:
The patent converts the inherent phase distortions and atmospheric turbulence effects, which are normally harmful to measurement accuracy, into beneficial compensation through optical phase conjugation. The phase-conjugated reference signal automatically reverses phase distortions, improving accuracy while the nonlinear optical process itself provides the solution rather than requiring additional complex correction mechanisms
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 high-precision covert sensing and communication by reducing detectability, achieving improved accuracy and sensitivity through quantum entanglement-assisted waveform coding, phase conjugation, and optical delay techniques.
Implementation Method 1
The light source generates broadband light and from that pairs of entangled photons that form a reference and a signal at different wavelengths
Implementation Method 2
A phase conjugator mixes the reference with the broadband light to shift the reference to the same wavelength as the signal and performs a phase conjugation to output a phase conjugated reference as a local oscillator
Implementation Method 3
An optical delay time delays the local oscillator to approximately match a time-of-flight delay to the target and back
Implementation Method 4
Light returned from the target is combined with the local oscillator, detected using direct detection, heterodyne, homodyne or quasi-homodyne techniques
Implementation Method 5
Light returned from the target is combined with the local oscillator, detected using direct detection, heterodyne, homodyne or quasi-homodyne techniques
Data Source
AI summary
A system for covert sensing and communications encodes a broadband light source using quantum entanglement-assisted waveform coding to spread a narrow-band signal over frequency. The light source generates broadband light and from that pairs of entangled photons that form a reference and a signal at different wavelengths. The signal is modulated and transmitted to illuminate a target. A phase conjugator mixes the reference with the broadband light to shift the reference to the same wavelength as the signal and performs a phase conjugation to output a phase conjugated reference as a local oscillator. An optical delay time delays the local oscillator to approximately match a time-of flight delay to the target and back. Light reflected from the target is combined with the local oscillator, detected using direct detection heterodyne, homodyne or quasi-homodyne techniques, demodulated and decoded to recover the narrow-band signal and estimate the phase of the reflected light relative to the transmitted light to provide fine range estimates for the target and a covert communications channel.