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A phaseonium magnetometer: A new optical magnetometer based on index enhanced media

Marlan O. Scully, Michael D. Fleischauer, M. B. Graf

Published Jan 1, 1993• 0 citations
OpenAlex

Abstract

An optical magnetometer based on quantum coherence and interference effects in atoms is proposed. The sensitivity of this device is potentially superior to the present state-of-the-art devices. Optimum operating conditions are derived, and a comparison to standard optical pumping magnetometers is made.

Related papers

Quantum sensitivity limits of an optical magnetometer based on atomic phase coherence

Michael Fleischhauer, Marlan O. Scully

An optical magnetometer based on atomic coherence effects is analyzed using a quantum Langevin approach. The large dispersion of a phase-coherent atomic medium (``phaseonium'') at a point of vanishing absorption is used to detect magnetic level shifts via optical phase measurements in a Mach-Zehnder interferometer with sensitivities potentially superior to state-of-the-art devices. Effects of Doppler broadening and fluctuations of the driving field are discussed and a comparison to standard optical-pumping magnetometers is made.

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High-sensitivity magnetometer based on index-enhanced media

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The large dispersion of a phase-coherent medium, at a point of vanishing absorption, is applied to interferometric measurements of detuning between atomic and radiation frequencies. It is shown that, under certain conditions, the interferometer quantum-limited operation is determined by vacuum-fluctuation shot noise while the noise introduced by the interaction of the probe field with the phase-coherent atoms can be made negligible. As a possible application, an optical magnetometer is analyzed whose sensitivity is shown to be potentially superior to the present state-of-the-art devices.

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Phaseonium: media of unusual optical properties

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In recent years reports on very interesting media showing unusual optical properties have appeared in literature on atomic physics. The source of these properties is quantum interference revealed in the process of interaction of atoms with coherent light. The basis of this process is the fact that if there are at least two possibilities of realization of the process of absorption or emission of light in a given medium leading to the same final state, they interfere with each other. The result of the interference depends on relative phases of the interfering processes. However, for the interference to be observable the above phases must be well determined. The phase coherence of the medium is thus a condition necessary for obtaining the optical properties characteristic of quantum interference. This fact has been underlined by the name phaseonium given to these media by Marlan O. Scully. Recently observed unusual optical properties of a phase-coherent atomic medium (phaseonium) is explained using very simple models.

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Assessment of Relaxation Components in Optically Pumped Magnetometers Under Operational Conditions

Huanyu Zhou, Yi Zhangu, Jin Liu +3 more

The deterioration of spin coherence has been a significant challenge in the field of quantum magnetic measurements based on optically pumped atomic magnetometers (OPAMs). However, measurement and evaluation methods for specific relaxation components of OPAMs under working conditions remain lacking, which impedes further improvement in OPAM performance. To address this, we propose a methodology for quantifying the relaxation components of an OPAM under realistic operating conditions. Using this method, we confirm the existence of an anomalous relaxation mechanism induced by radio-frequency (RF) magnetic fields and develop an empirical expression to describe its behavior. The results experimentally demonstrate that, in addition to the well-known spin-exchange relaxation, the dominant contributions to spin relaxation arise from optical pumping and RF magnetic fields. This work paves the way for sensitivity enhancement in quantum magnetometry and refines the theoretical understanding of relaxation mechanisms in OPAMs.

IEEE Transactions on Instrumentation and Measurement•Jan 1, 2026•1 citation

Sensitivity Improvement of Spin-Exchange Relaxation Free Atomic Magnetometers by Hybrid Optical Pumping of Potassium and Rubidium

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An optically pumped atomic magnetometer using a hybrid cell of potassium and rubidium atoms was demonstrated to yield high sensitivity to magnetic fields. We operated the magnetometer with the four possible combinations of optically pumped and optically probed atoms and found that the combination of optically pumped potassium and optically probed rubidium showed the highest sensitivity among the four combinations because the rubidium atoms were denser than those of potassium. Furthermore, we investigated the dependence of the sensitivity on the power densities of the pump and probe beams and the wavelength of the probe beam. The magnetometer using the hybrid cell required higher pump-beam power and had narrower magnetic linewidth than those of the single alkali-metal cell. However, the magnetic linewidth was larger than the theoretical value, ignoring the spin relaxation caused by the spin-exchange collisions. By adjusting the laser conditions, the highest sensitivity approached 30 fTrms/Hz1/2.

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Ultra-Sensitive Optical Atomic Magnetometers and Their Applications

Igor Savukov

Advances in Optical and Photonic Devices 330 integration into microfabricated packages.Such packages will be not only inexpensive and easy to batch produce they will also have lower power consumption, light weight and unimpeded mobility (Knappe et al., 2006).Sensitive magnetic field measurements, for which AMs can be used, are important owing to many existing and potential applications.Magnetometers have been in wide use, for example, in geology, military, biomagnetism, space magnetic field measurements.AMs have been used because they are both relatively sensitive compared to conventional inexpensive magnetometers, such as fluxgates, and more convenient compared to SQUIDs that require cryogenic cooling.For a long time low-T c SQUIDs had been by far the most sensitive magnetometers at low frequency.However, this has changed with the demonstration with AMs of record 0.5 fT/Hz 1/2 sensitivity (Kominis et al., 2003).High-sensitivity AMs are based on spin-polarized atomic gases or vapors, and AM research is closely related to the atomic physics subfield dedicated to the investigation of spin interactions in such media.This subfield includes the research on optical pumping and related topics such as atomic clocks, masers, hyperpolarized gases, spin-based spectroscopy, and some others.A comprehensive review of optical pumping experiments before 1972 and theory of optical pumping and various relaxation mechanisms are given by William Happer (Happer, 1972).This theory, which still stands the test of time, includes the formulation of density matrix equations, which can be directly applied to the analysis of magnetic resonances of vapors on which atomic magnetometers are based.Atomic magnetometers find many applications as other magnetometers, but they are most useful when high sensitivity and non-cryogenic operation are required.For example, AMs have been developed for submarine detection, and many other military applications are possible on similar principles.Some applications of Rb-vapor or 3 He magnetometers in geophysics and space physics were mentioned as early as in 1961 by Bloom (Bloom, 1961) who did some pioneering work on the high-sensitivity measurements of magnetic fields and theory for the operation of atomic magnetometers.Theoretical analysis of early atomic magnetometers was also done by Dehmelt (Dehmelt, 1957) and by Bell and Bloom (Bell & Bloom, 1957).Although the history of atomic magnetometers is quite fascinating and they played an important role in applications where simpler and less expensive methods did not provide sufficient sensitivity, the atomic magnetometers of the past were much less sensitive than the modern ones.Most exciting results appeared only recently with the various demonstrations of performance of high-density AMs, which we would like to focus on in this chapter. How to referenceIn order to correctly reference this scholarly work, feel free to copy and paste the following: Igor Savukov (2010).Ultra-Sensitive Optical Atomic Magnetometers and Their Applications, Advances in Optical and Photonic Devices, Ki Young Kim (Ed.),

InTech eBooks•Jan 1, 2010•11 citations
An optical magnetometer based on atomic coherence effects is analyzed using a quantum Langevin approach. The large dispersion of a phase-coherent atomic medium (``phaseonium'') at a point of vanishing absorption is used to detect magnetic level shifts via optical phase measurements in a Mach-Zehnder interferometer with sensitivities potentially superior to state-of-the-art devices. Effects of Doppler broadening and fluctuations of the driving field are discussed and a comparison to standard optical-pumping magnetometers is made.
The large dispersion of a phase-coherent medium, at a point of vanishing absorption, is applied to interferometric measurements of detuning between atomic and radiation frequencies. It is shown that, under certain conditions, the interferometer quantum-limited operation is determined by vacuum-fluctuation shot noise while the noise introduced by the interaction of the probe field with the phase-coherent atoms can be made negligible. As a possible application, an optical magnetometer is analyzed whose sensitivity is shown to be potentially superior to the present state-of-the-art devices.
In recent years reports on very interesting media showing unusual optical properties have appeared in literature on atomic physics. The source of these properties is quantum interference revealed in the process of interaction of atoms with coherent light. The basis of this process is the fact that if there are at least two possibilities of realization of the process of absorption or emission of light in a given medium leading to the same final state, they interfere with each other. The result of the interference depends on relative phases of the interfering processes. However, for the interference to be observable the above phases must be well determined. The phase coherence of the medium is thus a condition necessary for obtaining the optical properties characteristic of quantum interference. This fact has been underlined by the name phaseonium given to these media by Marlan O. Scully. Recently observed unusual optical properties of a phase-coherent atomic medium (phaseonium) is explained using very simple models.
The deterioration of spin coherence has been a significant challenge in the field of quantum magnetic measurements based on optically pumped atomic magnetometers (OPAMs). However, measurement and evaluation methods for specific relaxation components of OPAMs under working conditions remain lacking, which impedes further improvement in OPAM performance. To address this, we propose a methodology for quantifying the relaxation components of an OPAM under realistic operating conditions. Using this method, we confirm the existence of an anomalous relaxation mechanism induced by radio-frequency (RF) magnetic fields and develop an empirical expression to describe its behavior. The results experimentally demonstrate that, in addition to the well-known spin-exchange relaxation, the dominant contributions to spin relaxation arise from optical pumping and RF magnetic fields. This work paves the way for sensitivity enhancement in quantum magnetometry and refines the theoretical understanding of relaxation mechanisms in OPAMs.
An optically pumped atomic magnetometer using a hybrid cell of potassium and rubidium atoms was demonstrated to yield high sensitivity to magnetic fields. We operated the magnetometer with the four possible combinations of optically pumped and optically probed atoms and found that the combination of optically pumped potassium and optically probed rubidium showed the highest sensitivity among the four combinations because the rubidium atoms were denser than those of potassium. Furthermore, we investigated the dependence of the sensitivity on the power densities of the pump and probe beams and the wavelength of the probe beam. The magnetometer using the hybrid cell required higher pump-beam power and had narrower magnetic linewidth than those of the single alkali-metal cell. However, the magnetic linewidth was larger than the theoretical value, ignoring the spin relaxation caused by the spin-exchange collisions. By adjusting the laser conditions, the highest sensitivity approached 30 fTrms/Hz1/2.
Advances in Optical and Photonic Devices 330 integration into microfabricated packages.Such packages will be not only inexpensive and easy to batch produce they will also have lower power consumption, light weight and unimpeded mobility (Knappe et al., 2006).Sensitive magnetic field measurements, for which AMs can be used, are important owing to many existing and potential applications.Magnetometers have been in wide use, for example, in geology, military, biomagnetism, space magnetic field measurements.AMs have been used because they are both relatively sensitive compared to conventional inexpensive magnetometers, such as fluxgates, and more convenient compared to SQUIDs that require cryogenic cooling.For a long time low-T c SQUIDs had been by far the most sensitive magnetometers at low frequency.However, this has changed with the demonstration with AMs of record 0.5 fT/Hz 1/2 sensitivity (Kominis et al., 2003).High-sensitivity AMs are based on spin-polarized atomic gases or vapors, and AM research is closely related to the atomic physics subfield dedicated to the investigation of spin interactions in such media.This subfield includes the research on optical pumping and related topics such as atomic clocks, masers, hyperpolarized gases, spin-based spectroscopy, and some others.A comprehensive review of optical pumping experiments before 1972 and theory of optical pumping and various relaxation mechanisms are given by William Happer (Happer, 1972).This theory, which still stands the test of time, includes the formulation of density matrix equations, which can be directly applied to the analysis of magnetic resonances of vapors on which atomic magnetometers are based.Atomic magnetometers find many applications as other magnetometers, but they are most useful when high sensitivity and non-cryogenic operation are required.For example, AMs have been developed for submarine detection, and many other military applications are possible on similar principles.Some applications of Rb-vapor or 3 He magnetometers in geophysics and space physics were mentioned as early as in 1961 by Bloom (Bloom, 1961) who did some pioneering work on the high-sensitivity measurements of magnetic fields and theory for the operation of atomic magnetometers.Theoretical analysis of early atomic magnetometers was also done by Dehmelt (Dehmelt, 1957) and by Bell and Bloom (Bell & Bloom, 1957).Although the history of atomic magnetometers is quite fascinating and they played an important role in applications where simpler and less expensive methods did not provide sufficient sensitivity, the atomic magnetometers of the past were much less sensitive than the modern ones.Most exciting results appeared only recently with the various demonstrations of performance of high-density AMs, which we would like to focus on in this chapter. How to referenceIn order to correctly reference this scholarly work, feel free to copy and paste the following: Igor Savukov (2010).Ultra-Sensitive Optical Atomic Magnetometers and Their Applications, Advances in Optical and Photonic Devices, Ki Young Kim (Ed.),