Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:2405.12767 · New Journal of Physics

Postselected amplification applied to atomic magnetometers

Yazhi Niu, Jialin Li, Lupei Qin, Xin-Qi Li

Published Oct 22, 2025• 1 citation
arXivHTMLPDF

Abstract

Abstract We propose to embed the atomic magnetometer (AM) into an optical Mach–Zehnder interferometer (MZI). We analyze the effect of amplification of the Faraday rotation (FR) angle of the probe laser light, by properly postselecting the path-information state of the laser photons when passing through the MZI. In the presence of practical limitations, such as the polarization cross talk in the polarizing-beam-splitter, the amplified FR angle in the postselected photons can make the postselection scheme outperform the conventional measurement, thus further enhancing the sensitivity of the nowadays state-of-the-art optical AM.

DOI
10.1088/1367-2630/ae1634

Related papers

Postselected amplification applied to the Mach-Zehnder interferometer for phase-shift measurement of optical coherent states

Jialin Li, Yazhi Niu, Lupei Qin +1 more

We propose a postselected amplification scheme for phase-shift measurement of optical coherent states when passing through the Mach-Zehnder interferometer (MZI). Different from the usual weak-value-amplification (WVA) formulation, the which-path states of the MZI cannot be described as subsystem states entangled with two optical coherent states. However, we obtain the same phase amplification result of the usual WVA in the Aharonov-Albert-Vaidman limit but, beyond this limit, the result is essentially different. We explicitly carry out the amplified phase shift, which can be extracted out from the field-quadrature measurement in the dark port of the MZI. We also evaluate the performance quality of the proposed scheme and analyze the technical advantages by considering possible errors in the quadrature measurement.

arXiv:2411.16334•Physical Review A•Apr 21, 2025•5 citations

Atomic spin precession detection method based on the Mach-Zehnder interferometer in an atomic comagnetometer

Weijia Zhang, Lihong Duan, Wenfeng Fan +1 more

A new method for the detection of atomic spin precession based on the Mach-Zehnder interferometer (MZI) is proposed and experimentally demonstrated. Different from the conventional polarization detection methods which obtain the atomic spin precession signal by measuring the change of the probe laser power, the proposed method uses the laser modulated by an electro-optic phase modulator (EOM) as the source of the interferometer, and obtains the atomic spin precession signal by measuring the phase difference between the two arms of the MZI. The output of interferometer is independent of the probe laser power, which avoids the system error caused by the fluctuation of the probe laser power, and the long-term stability of the system is effectively improved. At the same time, the method adopts high-frequency electro-optic modulation, which can effectively suppress low-frequency noise, such as 1/f noise, and can significantly improve the detection sensitivity. The rotation sensitivity and long-term stability of the atomic comagnetometer were tested using the MZI detection method and a typical detection method, respectively. The comparison results show that the proposed method has the highest low frequency sensitivity and the potential to improve the long-term stability of the system.

Optics Express•Dec 6, 2022•6 citations

Single-Beam Atomic Magnetometer Enhanced With Elliptically Polarized Reflected Light

An‐Ning Xu, Jin Peng, Yiran Yin +1 more

The ultra-sensitivity magnetometer plays an important role in fundamental physics and applications, including magnetoencephalography (MEG) and magnetocardiography (MCG). The spin-exchange relaxation-free (SERF) atomic magnetometer (AM) has great sensitivity but is limited by the relatively complicated dual-beam structure for application, leading to the development of the compact AM based on one single laser beam. Compared with the single-beam optically pumped magnetometer (OPM) detecting the absorption of the circularly polarized beam, the SERF AM based on an elliptically polarized single beam detecting the optical rotation angle of polarization has a better response, lower laser power, and no need for signal modulation or demodulation. Here, we would like to report an elliptically-polarized single-beam SERF AM enhanced by reflecting the probe beam, increasing the light-atom interaction. Moreover, unlike the previous reflecting AM using the beam splitter, we used a D-shape mirror to extract the reflected beam, avoiding power losses of both incident and reflected beam and destruction of polarization. The sensitivity of our device in the reflecting scheme reaches 5 fT/Hz1/2 at 9–60 Hz, satisfying the need to measure the human MEG/MCG or search for the fifth force. Our research paves the way for developing the compact SERF AM for multiple future applications.

IEEE Sensors Journal•Jun 27, 2024•7 citations

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.

Physical Review A•Mar 1, 1994•142 citations

Sensitive optical atomic magnetometer based on nonlinear magneto-optical rotation

Chris Hovde, Brian Patton, Eric Corsini +2 more

A self-oscillating magnetometer based on nonlinear magneto-optical rotation using amplitude-modulated pump light and unmodulated probe light (AM-NMOR) in 87Rb has been constructed and tested towards a goal of airborne detection of magnetic anomalies. In AM-NMOR, stroboscopic optical pumping via amplitude modulation of the pump beam creates alignment of the ground electronic state of the rubidium atoms. The Larmor precession causes an ac rotation of the polarization of a separate probe beam; the polarization rotation frequency provides a measure of the magnetic field. An anti-relaxation coating on the walls of the atomic vapor cell results in a long lifetime of 56 ms for the alignment, which enables precise measurement of the precession frequency. Light is delivered to the magnetometer by polarization-maintaining optical fibers. Tests of the sensitivity include directly measuring the beat frequency between the magnetometer and a commercial instrument and measurements of Earth's field under magnetically quiet conditions, indicating a sensitivity of at least 5 pT/νHz. Rotating the sensor indicates a heading error of less than 1 nT, limited in part by residual magnetism of the sensor.

arXiv:1003.1531•Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Apr 23, 2010•6 citations

Closed-loop atomic spin polarization detection based on EOAM modulation in K-Rb-21Ne co-magnetometers

Shimiao Fan, Wenfeng Fan, Qi Yuan +4 more

We propose a high-sensitivity spin polarization detection scheme based on optical amplitude modulation in atomic co-magnetometers, which is different from the traditional configuration.A linearly polarized laser with intensity modulation interacts with electron spins, generating optical rotation angles.Through differential amplification and demodulation, atomic spin polarization information is extracted with high precision.The effectiveness of the proposed method is verified by applying external perturbations during testing.Compared to traditional detection methods, the proposed approach effectively enhances inertial measurement sensitivity.Specifically, at 1 Hz, the measurement sensitivity has improved from 9.7 × 10 -6 to 3.25 × 10 -6 deg/(s Hz 1/2 ).Furthermore, the proposed scheme is easily integrable and conducive to future research on miniaturizing co-magnetometers and can also be applied to many other related fields.

Chinese Optics Letters•Jan 1, 2024•4 citations
Abstract We propose to embed the atomic magnetometer (AM) into an optical Mach–Zehnder interferometer (MZI). We analyze the effect of amplification of the Faraday rotation (FR) angle of the probe laser light, by properly postselecting the path-information state of the laser photons when passing through the MZI. In the presence of practical limitations, such as the polarization cross talk in the polarizing-beam-splitter, the amplified FR angle in the postselected photons can make the postselection scheme outperform the conventional measurement, thus further enhancing the sensitivity of the nowadays state-of-the-art optical AM.
We propose a postselected amplification scheme for phase-shift measurement of optical coherent states when passing through the Mach-Zehnder interferometer (MZI). Different from the usual weak-value-amplification (WVA) formulation, the which-path states of the MZI cannot be described as subsystem states entangled with two optical coherent states. However, we obtain the same phase amplification result of the usual WVA in the Aharonov-Albert-Vaidman limit but, beyond this limit, the result is essentially different. We explicitly carry out the amplified phase shift, which can be extracted out from the field-quadrature measurement in the dark port of the MZI. We also evaluate the performance quality of the proposed scheme and analyze the technical advantages by considering possible errors in the quadrature measurement.
A new method for the detection of atomic spin precession based on the Mach-Zehnder interferometer (MZI) is proposed and experimentally demonstrated. Different from the conventional polarization detection methods which obtain the atomic spin precession signal by measuring the change of the probe laser power, the proposed method uses the laser modulated by an electro-optic phase modulator (EOM) as the source of the interferometer, and obtains the atomic spin precession signal by measuring the phase difference between the two arms of the MZI. The output of interferometer is independent of the probe laser power, which avoids the system error caused by the fluctuation of the probe laser power, and the long-term stability of the system is effectively improved. At the same time, the method adopts high-frequency electro-optic modulation, which can effectively suppress low-frequency noise, such as 1/f noise, and can significantly improve the detection sensitivity. The rotation sensitivity and long-term stability of the atomic comagnetometer were tested using the MZI detection method and a typical detection method, respectively. The comparison results show that the proposed method has the highest low frequency sensitivity and the potential to improve the long-term stability of the system.
The ultra-sensitivity magnetometer plays an important role in fundamental physics and applications, including magnetoencephalography (MEG) and magnetocardiography (MCG). The spin-exchange relaxation-free (SERF) atomic magnetometer (AM) has great sensitivity but is limited by the relatively complicated dual-beam structure for application, leading to the development of the compact AM based on one single laser beam. Compared with the single-beam optically pumped magnetometer (OPM) detecting the absorption of the circularly polarized beam, the SERF AM based on an elliptically polarized single beam detecting the optical rotation angle of polarization has a better response, lower laser power, and no need for signal modulation or demodulation. Here, we would like to report an elliptically-polarized single-beam SERF AM enhanced by reflecting the probe beam, increasing the light-atom interaction. Moreover, unlike the previous reflecting AM using the beam splitter, we used a D-shape mirror to extract the reflected beam, avoiding power losses of both incident and reflected beam and destruction of polarization. The sensitivity of our device in the reflecting scheme reaches 5 fT/Hz1/2 at 9–60 Hz, satisfying the need to measure the human MEG/MCG or search for the fifth force. Our research paves the way for developing the compact SERF AM for multiple future applications.
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.
A self-oscillating magnetometer based on nonlinear magneto-optical rotation using amplitude-modulated pump light and unmodulated probe light (AM-NMOR) in 87Rb has been constructed and tested towards a goal of airborne detection of magnetic anomalies. In AM-NMOR, stroboscopic optical pumping via amplitude modulation of the pump beam creates alignment of the ground electronic state of the rubidium atoms. The Larmor precession causes an ac rotation of the polarization of a separate probe beam; the polarization rotation frequency provides a measure of the magnetic field. An anti-relaxation coating on the walls of the atomic vapor cell results in a long lifetime of 56 ms for the alignment, which enables precise measurement of the precession frequency. Light is delivered to the magnetometer by polarization-maintaining optical fibers. Tests of the sensitivity include directly measuring the beat frequency between the magnetometer and a commercial instrument and measurements of Earth's field under magnetically quiet conditions, indicating a sensitivity of at least 5 pT/νHz. Rotating the sensor indicates a heading error of less than 1 nT, limited in part by residual magnetism of the sensor.
We propose a high-sensitivity spin polarization detection scheme based on optical amplitude modulation in atomic co-magnetometers, which is different from the traditional configuration.A linearly polarized laser with intensity modulation interacts with electron spins, generating optical rotation angles.Through differential amplification and demodulation, atomic spin polarization information is extracted with high precision.The effectiveness of the proposed method is verified by applying external perturbations during testing.Compared to traditional detection methods, the proposed approach effectively enhances inertial measurement sensitivity.Specifically, at 1 Hz, the measurement sensitivity has improved from 9.7 × 10 -6 to 3.25 × 10 -6 deg/(s Hz 1/2 ).Furthermore, the proposed scheme is easily integrable and conducive to future research on miniaturizing co-magnetometers and can also be applied to many other related fields.