Matter-wave gravimeter magic field calibration
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Solution Overview
Problem
Gravimeters using matter waves face challenges in precision due to fluctuations in magnetic fields, particularly the stability of the separation distance between atomic wave packets, which limits measurement accuracy and coherence time.
Innovation Solution
A gravimeter employing 'contaminated states' with a magnetostatic field adjusted to be independent of microwave field fluctuations, using calibration means to determine a 'magic' field that minimizes energy differences between internal states, allowing for precise measurement of the local gravitational field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a microwave field is applied to separate atoms into two wave packets, then the measurement of gravitational field is enabled, but the magnetic field fluctuations cause instability in the separation distance and reduce coherence time
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the magnetostatic field strength to compensate for microwave field fluctuations. The system measures the actual microwave field strength and modifies the magnetostatic field accordingly, transforming the system from being sensitive to field fluctuations into being robust against them, thereby maintaining stable separation distance and coherence time while enabling precise gravity measurements
2Duration of action of stationary object
If the magnetostatic field is adjusted to account for microwave field presence, then the coherence time is increased, but the system complexity increases due to calibration requirements
Solution Approach 1:
The patent implements feedback by continuously monitoring the microwave field strength and using this information to adjust the magnetostatic field in real-time. The system includes measurement means to detect the actual microwave field and control means to modify the magnetostatic field accordingly, creating a closed-loop system that maintains optimal conditions for coherence while managing the added complexity through automated control
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 enhances the stability of the measurement, increasing the coherence time and reducing uncertainties in the magnetic field fluctuations, thereby improving the precision of gravity measurements.
Implementation Method 1
a magnetostatic trap generating a magnetostatic field allowing the cloud of ultra-cold atoms to be trapped at a predetermined distance from the said measurement plane
Implementation Method 2
separating them into two separate packets of atomic waves by applying a microwave field which creates a different potential for the two internal states
Implementation Method 3
the said means comprising the application of at least a first microwave field and of a radiofrequency field
Implementation Method 4
The phase-shift ΔΦg induced by the local gravitation field g is written
Data Source
AI summary
The general field of the invention is that of matter-wave gravimeters. The gravimeter according to the invention comprises at least:means for generating, for capturing and for cooling a cloud of ultra-cold atoms;means of transferring the atoms into a superposition, with equal weights, of a first internal electronic state called state |1>) and of a second internal electronic state called state |2> comprising the application of at least a first microwave field and of a radiofrequency field;means for separating the atoms into two wave packets for a given period of time under the effect of at least a second microwave field, the said separation leading to a phase-shift associated with the local gravitational field;calibration means allowing a “magic” magnetostatic field to be determined for which the difference in energy between the first internal electronic state and the second internal electronic state is independent, to a first order, of the fluctuations of the magnetostatic field.