This happens when the light frequency is resonant with the atomic transitions of the medium, thus allowing the optical absorption to selleckbio take place. The dynamic range of an NMOR-based magnetometer is limited by the width of the resonance, and the sensitivity that can be obtained is around 0.15pT/Hz1/2 [5], which is adequate for geomagnetic measurements. The magnetometers operating in the SERF regime are also based on NMOR principle. However, such magnetometers have limited sensitivities due to depolarization caused by various atoms interaction types. The dominant type of these interactions is the spin-exchange collisions that can change the hyperfine state of the atoms while preserving the total angular momentum of the colliding atom pair.

This results in a decoherent precession of the atom ensemble in the presence of a magnetic field, which makes the measurement of the Larmor frequency difficult. However, decoherence due to spin-exchange collisions can be completely eliminated if the spin-exchange collisions occur faster than the precession frequency of the atoms. This kind of optical magnetometers can reach a sensitivity of 0.54fT/Hz1/2 [6]. The Mx magnetometers are so called because an rf oscillating magnetic field is supplied to the atoms to modulate the x-component of the magnetization vector inside the vapor cell. The phase difference between the driving rf signal and the probe light transmitted through the vapor cell gives a direct measurement of the Larmor frequency. This kind of magnetometer is vastly used in magnetocardiography, and it can reach sensitivity of 99fT/Hz1/2 [7].

Optical magnetometers based on CPT and SERF regime operate in zero-magnetic-fieldconditions while the others require a weak magnetic field to induce Zeeman splitting. Between all the operation modes of optical magnetometers, the Mx configuration and SERF regime can achieve the highest sensitivity. An attractive feature of magnetometers working in the SERF regime is that they do not need an rf magnetic field or magnetic coils in the proximity of the vapor cell, which could create crosstalk problems in array configurations. On the other hand, the SERF regime requires higher temperature to attain high sensitivity and only works in very weak magnetic fields because the frequency of collisions must be higher than the Larmor frequency.

This makes the SERF regime much more susceptible to environmental noise. In this paper, we describe the principle Cilengitide of operation of an Mx-configuration-based optically pumped quantum magnetometer and demonstrate experimentally the dependence of its sensitivity and bandwidth upon the light power and the alkali vapor temperature. The paper is organized as follows. In Section 2, we explain the principle of operation of an optical Mx magnetometer. In Section 3, the experimental setup is described.