Microwave Reflection Sensing for Non-Destructive Cold Atom Counting

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Solution Overview

Problem

Current cold atom sensors face limitations due to destructive optical detection methods, which result in downtime and stability issues, and are not compatible with compact, low-power inertial sensors, restricting their bandwidth and compatibility with compact designs.

Innovation Solution

A non-destructive, non-optical method using a microwave-based device integrated with an atom chip to measure the population of cold atoms by detecting atomic and reference reflected powers, amplitudes, or phases, allowing multiple measurements from the same cloud of atoms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If destructive optical detection methods are used to measure atom population, then measurement can be performed, but the atom cloud is destroyed requiring re-preparation, causing downtime and stability issues

Engineering Contradiction:
Improveatom population measurementVSAvoidsensor stability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent replaces the optical detection system with a microwave detection system. Instead of using lasers to illuminate and detect atoms (optical method), the invention uses microwave fields to interact with the atoms and detect their population through microwave signal reflections. This substitution allows non-destructive measurement, eliminating the need to re-prepare the atom cloud after each measurement, thus improving sensor stability and continuity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention changes the detection parameter from optical frequency to microwave frequency. By detecting atoms using microwave fields at lower frequencies rather than optical frequencies, the measurement becomes non-destructive. This parameter change allows the same atom cloud to be measured multiple times without degradation, resolving the contradiction between measurement capability and sensor stability.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If complex optical systems are used for detection, then atom population can be measured, but the device becomes incompatible with compact, low-power inertial sensor designs

Engineering Contradiction:
Improveatom population measurementVSAvoidoptical system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the complex optical detection system with a simpler microwave detection system. The microwave system can be integrated directly into the atom chip structure using standard microwave circuitry, eliminating the need for complex optical components such as lasers, mirrors, and detectors. This substitution dramatically reduces device complexity and enables compact, low-power inertial sensor designs.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The microwave detection system serves multiple functions within the atom chip architecture. The same microwave circuitry that guides and manipulates atoms can also detect atom population, eliminating the need for separate dedicated detection components. This multi-functionality reduces overall device complexity and improves compatibility with compact designs.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Productivity

If destructive detection methods are used, then measurement can be performed, but continuous measurement is not possible without re-preparing the atom cloud

Engineering Contradiction:
Improvemeasurement rateVSAvoiddowntime for re-preparation
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The patent replaces destructive optical detection with non-destructive microwave detection, enabling continuous measurement. The microwave fields used for detection do not destroy the atom cloud, allowing multiple sequential measurements to be performed on the same atoms without interruption. This eliminates the downtime required for re-preparing atom clouds between measurements, significantly improving measurement rate and productivity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention enables continuous measurement by using a detection method that does not consume or destroy the measured object. The microwave detection system can continuously probe the atom cloud without depleting it, maintaining uninterrupted measurement capability and eliminating idle time between measurement cycles.

Inventive Principle:
Principle #20Continuity of useful action

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 enables continuous measurement without re-preparing the atom cloud, enhancing sensor stability and bandwidth, and simplifies the design for compact, low-power inertial sensors by eliminating the need for complex optical systems.

Implementation Method 1

recovering a reflected signal SMWra originating from a reflection of the incident signal by said cloud

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP4168736B1Device for measuring a quantity representative of a population of cold atoms and associated sensor
Publication Date: 2024.04.17 OBSERVATOIRE DE PARIS
  • EP4168736B1 patent drawingFigure 1
  • EP4168736B1 patent drawingFigure 2
  • EP4168736B1 patent drawingFigure 3

AI summary

The invention relates to a device (1, 2) for measuring a quantity (ΓA) representative of a population (N) of cold atoms, the cold atoms being located in a cloud (CL) of cold atoms to be analysed, the device comprising: - a microwave source (S) configured to generate an incident signal (SMWi) at a predetermined signal frequency (fs), - a microwave guide (GO) configured to propagate the incident signal and an antenna (Ant) configured to emit the incident signal towards the cloud of cold atoms and its environment, the antenna and the microwave guide also being suitable for recovering an atomic reflected signal (SMWra) originating from a reflection of the incident signal by the cloud and its environment, and which propagates in the wave guide in the opposite direction to the incident signal, - a separation device (SS) coupled to the microwave guide and configured to extract at least part of the atomic reflected signal, - a detector (Det) configured to detect the atomic reflected signal extracted by the separation device, the quantity representative of the population of cold atoms (N) being obtained from a detected value (SA) of the atomic reflected signal (SMWra), and a detected value (S0) of a signal reflected by the environment in the absence of the cloud, referred to as the reference reflected signal (SMWr0).