In this Letter, we propose a single-beam nonlinear magneto-optical rotation (NMOR) magnetometer with a multipass 4 He gas-discharged cell. In contrast to the single-pass cell, the multipass cell allowed laser beams to pass through the metastable-state atomic ensemble 22 times, which directly increases the optical path length and significantly enhances magneto-optical rotation in the 4 He gas sample. Based on nonlinear Faraday rotation, the 4 He magnetometer with the multipass cell demonstrates a noise floor of 9 fT/Hz 1/2 , which approaches the photon-shot noise floor limit of 6.4 fT/Hz 1/2 . In addition, the wider linewidth in metastable-state atoms realizes an NMOR 4 He magnetometer with a 3 dB bandwidth of 4.3 kHz, in contrast to the ultranarrow linewidth in the antirelaxation-coated cells or spin-exchange relaxation-free regime alkali-metal cells with buffer gas. Since the 4 He cell functions without heating or cryogenic cooling, the femtotesla sensitivity and kilohertz-bandwidth 4 He magnetometer exhibits potential in biomagnetic applications such as magnetocardiography and magnetoencephalography.In this Letter, we propose a single-beam nonlinear magneto-optical rotation (NMOR) magnetometer with a multipass 4 He gas-discharged cell. In contrast to the single-pass cell, the multipass cell allowed laser beams to pass through the metastable-state atomic ensemble 22 times, which directly increases the optical path length and significantly enhances magneto-optical rotation in the 4 He gas sample. Based on nonlinear Faraday rotation, the 4 He magnetometer with the multipass cell demonstrates a noise floor of 9 fT/Hz 1/2 , which approaches the photon-shot noise floor limit of 6.4 fT/Hz 1/2 . In addition, the wider linewidth in metastable-state atoms realizes an NMOR 4 He magnetometer with a 3 dB bandwidth of 4.3 kHz, in contrast to the ultranarrow linewidth in the antirelaxation-coated cells or spin-exchange relaxation-free regime alkali-metal cells with buffer gas. Since the 4 He cell functions without heating or cryogenic cooling, the femtotesla sensitivity and kilohertz-bandwidth 4 He magnetometer exhibits potential in biomagnetic applications such as magnetocardiography and magnetoencephalography.

Optics LettersSep 19, 202221 citations

A millimeter-scale atomic magnetometer

Peter D. D. Schwindt, John E. Kitching, Svenja A. Knappe +4 more

Bulletin of the American Physical SocietyMay 18, 20050 citations

Subfemtotesla Scalar Atomic Magnetometry Using Multipass Cells

D. Sheng, Lun Li, Nezih Dural +1 more

Scalar atomic magnetometers have many attractive features but their sensitivity has been relatively poor. We describe a Rb scalar gradiometer using two multipass optical cells. We use a pump-probe measurement scheme to suppress spin-exchange relaxation and two probe pulses to find the spin precession zero crossing times with a resolution of 1 psec. We realize a magnetic field sensitivity of 0.54 fT/Hz(1/2), which improves by an order of magnitude the best scalar magnetometer sensitivity and exceeds, for example, the quantum limit set by the spin-exchange collisions for a scalar magnetometer with the same measurement volume operating in a continuous regime.Scalar atomic magnetometers have many attractive features but their sensitivity has been relatively poor. We describe a Rb scalar gradiometer using two multipass optical cells. We use a pump-probe measurement scheme to suppress spin-exchange relaxation and two probe pulses to find the spin precession zero crossing times with a resolution of 1 psec. We realize a magnetic field sensitivity of 0.54 fT/Hz(1/2), which improves by an order of magnitude the best scalar magnetometer sensitivity and exceeds, for example, the quantum limit set by the spin-exchange collisions for a scalar magnetometer with the same measurement volume operating in a continuous regime.

arXiv:1208.1099Physical Review LettersApr 18, 2013365 citations

Frequency Tunable Atomic Magnetometer based on an Atom Interferometer

Frank A. Narducci, Danielle Braje, Jon P. Davis +1 more

Bulletin of the American Physical SocietyJun 4, 20130 citations

Femtotesla Spin-Exchange Relaxation-Free Atomic Magnetometer With a Multipass Cell

Yibo Qi, Bo Li, Shuying Wang +3 more

Miniaturized high-sensitivity atomic magnetometers play a crucial role in biomagnetic measurements. The utilization of multipass cells enhances the sensitivity of atomic magnetometers. This study explores the benefits of employing a multipass cell in spin-exchange relaxation-free (SERF) atomic magnetometers through theoretical and experimental analysis. A signal-to-noise ratio (SNR) model was established by accounting for the optimal detuning frequency of the probe light and low-frequency 1/f noise. This enabled the optimal number of probe light passes through the vapor cell to be determined. Additionally, compact and symmetric reflective optical paths were designed to mitigate polarization gradients in atomic magnetometers with high atomic number density. Experimental results confirmed that the magnetic field sensitivity of the triple-pass configuration (1.8 fT/Hz $^{1/2}$ ) was 1.89 times that of the single-pass configuration (3.4 fT/Hz $^{1/2}$ ), consistent with the theoretical analysis. This study provides valuable theoretical guidance for analyzing the SNR performance of SERF atomic magnetometers and demonstrates the potential of multipass cells in enhancing their magnetic field sensitivity. The utilization of multipass cells presents a viable approach toward the realization of highly sensitive and portable miniaturized SERF atomic magnetometers.Miniaturized high-sensitivity atomic magnetometers play a crucial role in biomagnetic measurements. The utilization of multipass cells enhances the sensitivity of atomic magnetometers. This study explores the benefits of employing a multipass cell in spin-exchange relaxation-free (SERF) atomic magnetometers through theoretical and experimental analysis. A signal-to-noise ratio (SNR) model was established by accounting for the optimal detuning frequency of the probe light and low-frequency 1/f noise. This enabled the optimal number of probe light passes through the vapor cell to be determined. Additionally, compact and symmetric reflective optical paths were designed to mitigate polarization gradients in atomic magnetometers with high atomic number density. Experimental results confirmed that the magnetic field sensitivity of the triple-pass configuration (1.8 fT/Hz$^{1/2}$) was 1.89 times that of the single-pass configuration (3.4 fT/Hz$^{1/2}$), consistent with the theoretical analysis. This study provides valuable theoretical guidance for analyzing the SNR performance of SERF atomic magnetometers and demonstrates the potential of multipass cells in enhancing their magnetic field sensitivity. The utilization of multipass cells presents a viable approach toward the realization of highly sensitive and portable miniaturized SERF atomic magnetometers.

IEEE Transactions on Instrumentation and MeasurementJan 1, 202418 citations

Optical Magnetometry using Multipass Cells with overlapping beams

Nathaniel David McDonough, Vito Giovanni Lucivero, Nezih Dural +1 more

Bulletin of the American Physical SocietyJun 8, 20170 citations

^{1/2}

) was 1.89 times that of the single-pass configuration (3.4 fT/Hz

^{1/2}

), consistent with the theoretical analysis. This study provides valuable theoretical guidance for analyzing the SNR performance of SERF atomic magnetometers and demonstrates the potential of multipass cells in enhancing their magnetic field sensitivity. The utilization of multipass cells presents a viable approach toward the realization of highly sensitive and portable miniaturized SERF atomic magnetometers.