System and method for time-multiplexed dual atomic magnetometry
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Publication Number
US-12000911-B2
Publication Date
2024-06-04
Expiration Date
Abstract
A time-multiplexed dual atomic magnetometer includes first and second vapor cells such that an external magnetic field induces Larmor precession of atoms within the vapor cells. The magnetometer includes first and second polarimeters for measuring first and second polarizations of first and second probe beams that propagate through the first and second vapor cells, respectively. The magnetometer includes a controller that gates the probe beams such that (i) the first probe beam propagates through the first vapor cell during a first measurement stage, (ii) the second probe beam does not propagate through the second vapor cell during the first measurement stage, (iii) the second probe beam propagates through the second vapor cell during a second measurement stage that begins when the first measurement stage ends, and (iv) the first probe beam does not propagate through the first vapor cell during the second measurement stage.
Core Innovation
The invention relates to time-multiplexed dual atomic magnetometry using first and second vapor cells positioned such that an external magnetic field induces Larmor precession of atoms confined within the first and second vapor cells. A first polarimeter measures a first polarization of a first probe beam after the first probe beam propagates through the first vapor cell, and a second polarimeter measures a second polarization of a second probe beam after the second probe beam propagates through the second vapor cell.
A controller gates the first and second probe beams so the first probe beam propagates through the first vapor cell during a first measurement stage. The first measurement stage begins when a second measurement stage ends, and the second measurement stage begins when the first measurement stage ends. The second probe beam does not propagate through the second vapor cell during the first measurement stage, while the second probe beam propagates through the second vapor cell during the second measurement stage; correspondingly, the first probe beam does not propagate through the first vapor cell during the second measurement stage.
The document further describes extracting a time-varying magnetic field without aliasing by using instantaneous-phase retrieval of exponentially decaying sinusoidal polarization data blocks, and concatenating or interleaving the blocks into a single gapless sequence. It includes computing an instantaneous Larmor frequency and forming a magnetic-field sequence from the polarization data, and addressing cases where the Larmor frequency differs between blocks by using interleaving with sign inversion of residual blocks.
Claims Coverage
The document includes two independent claims, one system claim and one method claim, each centered on a time-multiplexed gating scheme that alternates measurement between two adjacent vapor cells using respective probe beams and polarimeters. The claims recite staged propagation through only one vapor cell per time interval and identify the common inventive features across both claims.
Time-multiplexed dual atomic magnetometer with gated probe beams
A time-multiplexed dual atomic magnetometer including first and second vapor cells inducing Larmor precession under an external magnetic field, a first polarimeter measuring a first polarization of a first probe beam after propagation through the first vapor cell, a second polarimeter measuring a second polarization of a second probe beam after propagation through the second vapor cell, and a controller configured to gate the probe beams such that the first probe beam propagates through the first vapor cell during a first measurement stage while the second probe beam does not propagate through the second vapor cell during that first measurement stage, and vice versa during the second measurement stage.
Time-multiplexed dual atomic magnetometry with gated probe beams
A method for time-multiplexed dual atomic magnetometry including inducing Larmor precession of atoms confined within first and second vapor cells using an external magnetic field; measuring a first polarization of a first probe beam after propagation through the first vapor cell with a first polarimeter; measuring a second polarization of a second probe beam after propagation through the second vapor cell with a second polarimeter; and gating the first and second probe beams so that the first probe beam propagates through the first vapor cell during a first measurement stage while the second probe beam does not propagate through the second vapor cell during the first measurement stage, and the opposite propagation relationship holds during the second measurement stage.
Across both independent claims, the inventive thrust is the coordinated gating of first and second probe beams so that only one vapor cell is probed during each measurement stage, coupled with polarimetric measurement of probe-beam polarizations after propagation through the respective vapor cell under externally induced Larmor precession.
Stated Advantages
Eliminates time gaps in the recorded magnetic-field signal by enabling a gapless temporal sequence.
Enables extracting a time-varying magnetic field without aliasing using instantaneous-phase retrieval and gapless sequence construction.
Documented Applications
Magnetoencephalography.
NMR.
MRI.
Cancer therapy via measured time-varying molecular magnetic fields (siRNA/mRNA).
Geoscience applications.
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