Cold Atom Gravity Gradiometer with Segmented Optical Paths

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Solution Overview

Problem

Current gravity gradiometry techniques using cold atom traps face limitations in accuracy due to interference sources and require stringent optical conditions, which restrict the practical separation distance and increase complexity, making them slow and costly.

Innovation Solution

A cold atom gravity gradiometer system with first and second magneto-optical traps, each with mirrored surfaces to reflect laser beams, and an optical subsystem that transmits laser beams in opposite directions along longitudinal axes, allowing for adjustable baselines and reduced complexity, enabling more accurate and faster gravity gradient measurements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a common laser beam is used for both traps to achieve high common mode rejection, then measurement accuracy is improved, but optical requirements become stringent and device complexity increases

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidoptical requirements
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system divides the optical path into separate independent paths for each trap. Each trap has its own laser beam delivery system with separate optics, eliminating the need for a single complex common optical path while maintaining measurement accuracy through differential measurement techniques.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A single laser source is used to generate beams for both traps, but the beams are delivered through separate optical paths. This maintains the benefit of a common laser frequency while eliminating the optical complexity of a shared path, achieving multi-functionality with reduced complexity.

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

2Measurement precision

If the separation distance between cold atom clouds is increased to improve measurement capability, then gravity gradient measurement capability is improved, but optical shadowing increases and beam quality deteriorates

Engineering Contradiction:
Improvegravity gradient measurement capabilityVSAvoidoptical shadowing
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The optical paths for the two traps are completely separated, with each trap illuminated by its own independent laser beams. This segmentation allows each optical path to be optimized independently and eliminates optical shadowing effects that would occur in a shared path configuration, enabling greater separation distance between traps.

Inventive Principle:
Principle #1Segmentation

3Device complexity

If a single vacuum chamber is used for both traps to share common vacuum, then device complexity is reduced, but interference sources increase and measurement speed decreases

Engineering Contradiction:
Improvevacuum system complexityVSAvoidmeasurement speed
Core Design Contradiction:
Device complexityVSProductivity

Solution Approach 1:

The system uses two separate vacuum chambers, one for each trap. This segmentation allows independent optimization of vacuum conditions in each chamber, reduces cross-contamination and interference sources, and enables parallel operation that increases measurement speed, despite the increased complexity of having multiple vacuum systems.

Inventive Principle:
Principle #1Segmentation

4Adaptability or versatility

If laser beam is transmitted through multiple reflectors to reach both traps, then a single laser source can serve both traps, but diffraction and alignment issues increase

Engineering Contradiction:
Improvelaser beam utilizationVSAvoidalignment and diffraction control
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The system uses separate optical paths for each trap, with each path containing its own beam delivery optics. This segmentation eliminates the need for complex multi-reflector arrangements to share a single beam, reducing diffraction and alignment issues while still allowing a single laser source to serve both traps through independent beam generation.

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

This configuration enables more accurate and faster gravity gradient measurements over longer distances with reduced interference, lower cost, weight, and size, while maintaining stability and noise cancellation, allowing for the determination of multiple gravity gradient components with a compact and modular design.

Implementation Method 1

first and second magneto-optical traps, each having a plurality of mirrored surfaces arranged to reflect respective first and second incident laser beams to trap respective first and second cold atom clouds

Methodology Applied
Scientific EffectLaser cooling: Laser

Implementation Method 2

magneto-optical traps

Methodology Applied
Scientific EffectMagnetic field trapping: Magnetic Field

Implementation Method 3

each having a plurality of mirrored surfaces arranged to reflect respective first and second incident laser beams

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 4

a detection system for detecting acceleration of atoms trapped in the first and second magneto-optical traps

Methodology Applied
Scientific EffectAtomic interferometry: Interference

Implementation Method 5

allowing the cold atom samples to undergo free-fall

Methodology Applied
Scientific EffectGravity: Gravitation

Data Source

PatentEP3724695B1Gravity gradiometer
Publication Date: 2024.08.28 THE UNIV OF BIRMINGHAM
  • EP3724695B1 patent drawingFigure 1
  • EP3724695B1 patent drawingFigure 2
  • EP3724695B1 patent drawingFigure 3

AI summary

The disclosure relates to a gravity gradiometer comprising a pair of magneto-optical traps for measuring a gravity gradient. Example embodiments include a cold atom gravity gradiometer system (100) comprising: first and second magneto-optical traps (101, 102), each having a plurality of mirrored surfaces (103, 104) arranged to reflect an incident laser beam (105, 106) to trap respective first and second cold atom clouds (107, 108) separated from each other by a separation distance; an optical subsystem arranged to transmit a first laser beam (105) in a first direction along a first longitudinal axis towards the first magneto-optical trap (101) and a second laser beam (106) in an opposite second direction along a second longitudinal axis towards the second magneto-optical trap (102), the second longitudinal axis being parallel to the first longitudinal axis.