Impact of Thermal Induced Magnetic Noise on the Sensitivity of Atomic Magnetometers

Yijin Liu, Bin Wang, Di Gong +4 more

Spin-based sensors, such as magnetometers and comagnetometers, require precise control of thermal conditions and magnetic fields to achieve optimal performance. Thermal-magnetic coupling noise, induced by heating systems, is one of the limiting factors for sensitivity improvement. In this paper, the in-situ suppression method is proposed to eliminate thermal-magnetic coupling noise by employing the double-layer heater with dynamically adjustable current ratios. The in-situ method is verified across two distinct systems, including commercial magnetometer and the self-developed comagnetometer. For magnetometer system, the heating-induced magnetic interferences of the double-layer heater along three directions have been decreased over 2 orders compared to a conventional heater. Similarly, the total magnetic flux density has been suppressed by more than 78%. Furthermore, the thermal-magnetic coupling noise in K-Rb-21Ne comagnetometer equipped with the double-layer heater is in-situ suppressed to 6.54×10-9°/s/Hz1/2(0.01 fT/ Hz1/2) at 1 Hz, achieving a noise reduction of 22 dB compared to ex-situ method and 24 dB suppression relative to a conventional heater. Besides, the double-layer heater ensures a uniform and stable thermal field across the vapor cell, with a temperature variance less than 0.65 °C and a temperature fluctuation 65% lower than a conventional heater. This work advances ultra-sensitive quantum sensors by providing an effective method to in-situ suppress thermal-magnetic coupling noise.

Michael V. Romalis

W. C. Griffith, Ricardo Jiménez-Martínez, Vishal Shah +2 more

High permeability magnetic flux concentrators are used to enhance the sensitivity of an atomic magnetometer operating in the spin-exchange relaxation-free regime. The magnetometer uses a millimeter scale Rb87 vapor cell and either mu-metal or Mn–Zn ferrite flux concentrators. The measured sensitivity gives excellent agreement with calculations of thermal noise from the concentrator material. The mu-metal concentrators allow a sensitivity of 50fTHz−1∕2, limited by thermal current magnetic noise. The ferrite concentrators are limited by thermal magnetization noise at low frequencies, and reach a sensitivity of 10fTHz−1∕2 for frequencies above 125Hz.

李曙光, 徐云飞, 王兆英 +2 more

George E. Katsoprinakis, David Petrosyan, Iannis K. Kominis

Atomic magnetometers have achieved magnetic sensitivities in the subfemtotesla regime. Their bandwidth is determined by the transverse spin relaxation rate, 1/T2, which also determines the magnetic sensitivity. It is theoretically demonstrated that by using an electromagnetically induced transparent probe beam in a pump-probe atomic magnetometer, it is possible to operate the latter at frequencies much higher than its bandwidth, maintaining a high signal-to-noise ratio.

Guobin Liu, Xian-Ping Sun, 顾思洪 +2 more