Frequency Entangled Photon Detection via Direct Downconversion

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Solution Overview

Problem

Current systems for generating and detecting entangled photons are inefficient, requiring multiple non-linear optical shifts and pulsed operation, which reduces photon generation efficiency and increases complexity.

Innovation Solution

A method using an ultraviolet laser to generate a coherent beam, downconverted to produce frequency-entangled photons, with each pair sent along separate paths for detection, employing single photon detectors and coincidence counting to identify coincident photons within a time window, optimizing efficiency and speed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If multiple non-linear optical shifts are used to generate and detect entangled photons, then detection capability is achieved, but system complexity and operation time increase

Engineering Contradiction:

Improvephoton detection capabilityVSAvoidsystem complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the unnecessary upconversion detection stage from the traditional entangled photon detection system. By directly detecting downconverted photons in the near-infrared range, the system removes complex additional optical components and steps, thereby reducing system complexity while maintaining detection capability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of the conventional approach of upconverting photons to visible range for detection, the patent inverts the detection strategy by directly detecting downconverted near-infrared photons. This inversion simplifies the detection path and reduces the number of optical components required

Inventive Principle:

Principle #13The other way round (Inversion)

2Measurement precision

If pulsed laser operation is used to generate entangled photons, then detection timing is improved, but photon generation efficiency decreases

Engineering Contradiction:

Improvedetection timing precisionVSAvoidphoton generation efficiency

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent employs continuous-wave laser operation instead of pulsed operation, maintaining continuous photon generation and detection. This continuous operation mode eliminates the efficiency losses associated with pulsed operation while achieving adequate timing precision through coincidence counting within a defined time window

Inventive Principle:

Principle #20Continuity of useful action

3Measurement precision

If traditional downconversion and upconversion processes are used, then frequency-matched photons are produced, but photon generation speed and efficiency are reduced

Engineering Contradiction:

Improvefrequency matching precisionVSAvoidphoton generation speed

Core Design Contradiction:

Measurement precisionVSSpeed

Solution Approach 1:

The patent removes the upconversion stage from the traditional downconversion-upconversion process. By directly detecting the downconverted photons, the system eliminates the time-consuming upconversion step while maintaining frequency correlation through coincidence detection of entangled photon pairs

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent skips the intermediate upconversion step in the photon generation and detection process. By rushing directly from downconversion to detection in the near-infrared range, the system significantly accelerates photon generation speed while maintaining the essential frequency-matching capability through entanglement correlation

Inventive Principle:

Principle #21Skipping (Rushing through)

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 produces entangled photons at higher power, speed, and efficiency, with improved duty cycle and resolution, enabling faster image generation and higher signal collection in imaging applications.

Implementation Method 1

using an ultraviolet laser to generate a coherent beam

Methodology Applied

Scientific EffectStimulated emission: Laser

Implementation Method 2

non-linear crystals downconvert the coherent beam into frequency-entangled photons

Methodology Applied

Scientific EffectParametric downconversion:

Implementation Method 3

A first detector detects those photons sent along the first path, and a second detector detects those photons sent along the second path. The detection is performed in a single photon regime.

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentUS9134422B2Generation and detection of frequency entangled photons

Publication Date: 2015.09.15 THE BOEING CO

AI summary

An ultraviolet laser generates a coherent beam, which is downconverted to produce pairs of frequency-entangled photons. For each entangled pair, a first photon is sent along a first path and a second photon is sent along a second path. A first detector detects those photons sent along the first path, and a second detector detects those photons sent along the second path. The detection is performed in a single photon regime. Coincidence counting is performed on outputs of the detectors, including comparing leading edges on outputs of the first and second detectors within a time window.