Princeton University

University of Washington

Hi LLC

Michael Romalis

Nezih Dural

Wonjae Lee

Tom Kornack

Joel Allred

Rob Lyman

Mark Limes

Elizabeth Foley

Micah Ledbetter

William Happer

Ethan Pratt

Ricardo Jiménez-Martínez

Yuan-Yu Jau

Geoffrey Iwata

Eli Miron

Benjamin Shapiro

Karen L Sauer

Nicholas N Kuzma

Argyrios Dellis

Shuguang Li

Haifeng Dong

Kayla Wright-Freeman

Thomas Kornack

Amber B Post

Andrei Baranga

Ioannis Kominis

Igor M Savukov

Dong Sheng

Scott J Seltzer

Tao Wang

Seung-Kyun Lee

Vito Giovanni Lucivero

Vito-Giovanni Lucivero

Atomic magnetometers are usually used as scalar sensors to measure the magnitude of the magnetic field. The magnetic field is converted to a frequency that can be measured with high fractional precision. There are no comparable methods for measuring vector magnetic field components. Common sensors, such as flux-gate and SQUID magnetometers, suffer from calibration and orthogonality uncertainty. Disclosed is a method of using an atomic magnetometer to measure the magnitude and two polar angles of the magnetic field vector. The two polar angles are dimensionless quantities and can be measured with high fractional precision. Also disclosed is a particular measurement procedure that is immune to systematic effects in such measurements.

Pulsed vector magnetometer using a fast rotating field

According to various embodiments, a method for reducing heading error in a magnetometer that uses Rb-87 atoms is disclosed. The method includes varying a direction and magnitude of a magnetic field at different spin polarization regimes. According to various embodiments, a magnetometer adapted for reduced heading error is disclosed. The magnetometer includes a multipass cell containing Rb-87 vapor, a pump laser operated in a pulse mode that is synchronous with a Larmor frequency, and two orthogonal probe lasers configured to rotate to vary a direction and magnitude of a magnetic field at different spin polarization regimes.

System and method for heading error correction in a pulsed Rb-87 magnetometer at geomagnetic fields

According to various embodiments, a direct magnetic gradiometer having intrinsic subtraction of rotation signals from two oppositely polarized atomic ensembles within a single multi-pass cell is disclosed. The gradiometer includes three convex spherical mirrors aligned in a V-shape geometry. The three convex spherical mirrors include a front mirror and two back mirrors. The gradiometer further includes a probe laser beam. The laser beam is configured to be initially focused at a near-zero angle into a hole at a center of the front mirror such that the laser beam expands at the back mirrors and nearly overlaps with itself while undergoing multiple reflections between the front and back mirrors. The laser beam is further configured to be refocused to the front mirror at different spots in a number equal to half of total beam passes before exiting.

System and method for femtotesla direct magnetic gradiometer using a multipass cell

A magnetic field measurement system includes a magnetometer having at least one vapor cell, at least one light source to direct at least two light beams through the vapor cell(s), and at least one detector; at least one magnetic field generator to modify an external magnetic field experienced by the vapor cell(s); and at least one processor configured for: applying a first modulation pattern, b(t), to the magnetic field generator(s) to modulate a magnetic field at the vapor cell(s), where b(t)=[ccos(&#x3c9;t)+ssin(&#x3c9;t), ccos(&#x3c9;t)+ssin(&#x3c9;t), ccos(&#x3c9;t)+ssin(&#x3c9;t)], where c, s, c, s, c, and sare amplitudes and &#x3c9; is a frequency; directing the light source(s) to direct the light beams through the vapor cell(s); receiving signals from the detector(s); and determining three orthogonal components of the external magnetic field using the received signals. Multi-frequency modulation patterns can alternatively be used.

Devices, systems, and methods with optical pumping magnetometers for three-axis magnetic field sensing

Disclosed is a method and apparatus relating generally to scalar atomic magnetometers. The disclosed methods and apparatus utilize a pressurized sample chamber and a high frequency pulsed pump laser to increase spin polarization and significantly suppress heading errors. These methods and apparatus may also include alternating polarization of the pump light between pulses.

Pulsed scalar atomic magnetometer

A magnetometer for use with a sample including an atomic vapor includes a cell containing the sample such as a multipass cell including a first mirror element and a second mirror element configured so that an incoming light beam injected into the container will reflect multiple times between the first mirror element and the second mirror element. A polarized pump light source is configured to transmit pump light through the cell and pump the sample. A polarized probe light source configured to transmit probe light through the cell and probe the sample. A detector configured to detect a polarization angle or intensity of the probe light transmitted through the sample. A processor may be configured to calculate a precession frequency of the sample based on a first probe light pulse and a frequency correction based on a second probe light pulse.

Atomic magnetometry using pump-probe operation and multipass cells

The disclosure provides an optical apparatus including at least one optical element including glass, at least one support including silicon and a housing including glass. Furthermore, the at least one optical element and the at least one support can be anodically bonded together, and the at least one support and the housing can be anodically bonded together. The disclosure further provides a method for fabricating optical components with durable bonds and incorporates active alignment.

Anodically bonded cells with optical elements

A radio-frequency tunable atomic magnetometer for detection of nuclear quadrupole resonance (NQR) from room temperature solids, including detection of nitrogen-containing explosives placed external to a sensor unit. A potassium radio-frequency magnetometer with sensitivity of 0.24 fT/Hzoperating at 423 kHz is provided. The magnetometer detected aN NQR signal from room temperature ammonium nitrate (NHNO) in the zero-applied field limit. Results demonstrate first time detection of NQR with an atomic magnetometer, providing that a cryogen-free atomic magnetometer, with intrinsically frequency-independent sensitivity and easy tuning capabilities, can be an attractive new tool for detecting magnetic resonance signals in the kHz to MHz range. Low intensity magnetic fields are measured using an alkali metal vapor, by increasing magnetic polarization of the vapor to increase its sensitivity, then probing the magnetic polarization of the vapor to receive an output, and determining characteristics of the low intensity magnetic field from the output.

Subfemtotesla radio-frequency atomic magnetometer for nuclear quadrupole resonance detection

The present invention provides a high sensitivity atomic magnetometer and methods of measuring low intensity magnetic fields that relate to the use of an alkali metal vapor and a buffer gas; increasing the magnetic polarization of the alkali metal vapor thereby increasing the sensitivity of the alkali metal vapor to a low intensity magnetic field; probing the magnetic polarization of the alkali metal vapor, the probing means providing an output from the alkali metal vapor, the output including characteristics related to the low intensity magnetic field; and measuring means that receives the output, determines the characteristics of the low intensity magnetic field, and provides a representation of the low intensity magnetic field. In addition, the invention relates to a magnetometer and methods that provide a representation of a first magnetic field originating within a sample volume. The sample volume may be part or all of a subject, such as a human subject. The representation includes a representation of a source of a magnetic field occurring within the sample volume displayed in one, two, or three of three orthogonal Cartesian coordinates, referenced to the sample volume.

High sensitivity atomic magnetometer and methods for using same

The present invention provides a method and apparatus for increasing the intensity of coherent population trapping (CPT) resonances, used in atomic clocks and magnetometers, by pumping the atoms with light of alternating polarization. Pumping with such light, characterized by a photon spin vector that alternates in direction at a hyperfine frequency of the atoms at the location of the atoms, is referred to as push-pull pumping. In one embodiment of the system of the present invention, alkali-metal vapor is pumped with alternating circular-polarization Dlaser light that is intensity modulated at appropriate resonance frequencies, thereby exciting CPT resonances, which can be observed as increase in the mean transmittance of the alkali-metal vapor. These resonances are substantially enhanced due to an optically-induced concentration of atoms in the resonant energy sublevels.

Method and system for operating an atomic clock with alternating-polarization light

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Princeton, NJ, United States of America

Michael Romalis