Quantum Sensor Optical Readout with Dark-Field Noise Filtering

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Solution Overview

Problem

Existing quantum sensor systems face challenges with high optical noise and photon shot noise, requiring expensive detectors with large dynamic ranges due to the fluctuating photon counts, which can saturate and obscure the influence of the quantum system on the optical readout signal.

Innovation Solution

A sensor system employing a spatially dependent attenuator and imaging system forms a dark-field imaging setup to filter out DC components, reducing optical noise and photon counts, thereby allowing the use of simpler and potentially cheaper sensors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a large number of photons are used for optical readout, then the signal strength is improved, but the photon shot noise increases and the detector may saturate

Engineering Contradiction:
Improveoptical signal intensityVSAvoidsignal-to-noise ratio
Core Design Contradiction:
Illumination intensityVSMeasurement precision

Solution Approach 1:

The patent applies periodic modulation of the quantum system's excitation state using oscillating magnetic or electric fields. This periodic action causes the quantum system to emit modulated optical signals at specific frequencies, allowing the signal to be distinguished from background noise through frequency filtering, thereby improving signal-to-noise ratio without requiring high photon counts

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent introduces an intermediary detection method using quantum non-demolition measurement techniques. Instead of directly detecting photons, the system uses intermediate quantum states and resonant coupling to transfer information about the physical quantity being measured to optical signals, reducing direct photon detection noise while maintaining signal fidelity

Inventive Principle:
Principle #24Intermediary (Mediator)

2Illumination intensity

If a large number of photons are used for optical readout, then the signal strength is improved, but the detector dynamic range requirements increase

Engineering Contradiction:
Improveoptical signal intensityVSAvoiddetector dynamic range
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

By modulating the quantum system's emission at specific frequencies, the patent enables detection at lower average photon counts. The periodic signal allows use of AC coupling and frequency-selective detection, which reject DC offset and background light, reducing the dynamic range requirement of the detector

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent creates an optical copy of the quantum state information through resonant emission. The optical signal serves as a copy that encodes the measured physical quantity, allowing detection without directly measuring the quantum state, thus reducing detector requirements

Inventive Principle:
Principle #26Copying

3Device complexity

If conventional optical readout is used, then the system is simple, but the quantum system influence is obscured by noise

Engineering Contradiction:
Improvesystem complexityVSAvoidsensing sensitivity
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent introduces periodic modulation at the quantum system level, which imprints a characteristic frequency signature on the optical output. This allows the system to remain relatively simple optically while achieving high sensing sensitivity through frequency-domain analysis that separates signal from noise

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent changes the temporal parameters of the optical signal by modulating it at frequencies characteristic of the quantum system's transitions. This parameter transformation from static intensity to time-varying signal enables discrimination between quantum system influence and background noise, improving sensing sensitivity without significantly increasing system complexity

Inventive Principle:
Principle #35Parameter changes

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

The system achieves higher sensitivity and reduced dynamic range requirements, enabling more effective quantum sensing with improved signal-to-noise ratio and lower operational costs.

Implementation Method 1

The imaging system and the attenuator are configured to form a dark-field imaging system for the optical signal that filters out DC components from an image pattern of the optical signal

Methodology Applied
Scientific EffectOptical filtering: Filter (optical)

Implementation Method 2

an imaging system which is configured to apply a transformation to the optical signal, thereby generating a transformed optical signal at an image plane

Methodology Applied
Scientific EffectOptical transformation: Lens

Implementation Method 3

the excitation signal induces an emission and/or an adaption of an optical signal by the sensing volume, wherein at least one characteristic of the optical signal depends on the physical quantity

Methodology Applied
Scientific EffectOptical emission: Luminescence

Data Source

PatentEP4484989B1Sensor system and method for sensing a physical quantity
Publication Date: 2026.02.25 ROHDE & SCHWARZ GMBH & CO KG
  • EP4484989B1 patent drawingFigure 1
  • EP4484989B1 patent drawingFigure 2
  • EP4484989B1 patent drawingFigure 3

AI summary

The present disclosure relates to a quantum sensor system 10 for sensing a physical quantity. The sensor system comprises: an excitation source 11 which is configured to generate an excitation signal 12; a sensing volume 13 comprising one or more quantum systems, wherein the sensing volume is arranged to receive the excitation signal, wherein the excitation signal induces an emission and/or an adaption of an optical signal 14 by the sensing volume, wherein at least one characteristic of the optical signal depends on the physical quantity; an imaging system 15 which is configured to apply a transformation to the optical signal, thereby generating a transformed optical signal at an image plane 16; a spatially dependent attenuator 17 which is arranged at the image plane and which is configured to attenuate the transformed optical signal; an optical sensor 18 which is configured to capture the thus attenuated optical signal and to detect an image formed by the optical signal; and a processor 19 which is configured to extract an information on the physical quantity from the captured image pattern.