Atomic Magnetometer Multisensor Array for rf Interference Mitigation and Unshielded Detection of Nuclear Quadrupole Resonance

Abstract

An array of four 87 Rb vector magnetometers are used to detect nuclear quadrupole resonance (NQR) signals in an unshielded environment at 1 MHz. With a baseline of 25 cm, the length of the array, radio-frequency interference mitigation (RFIM) is also demonstrated; a radio-station signal is suppressed by a factor of 20 without degradation to the signal of interest. With these compact sensors, in which the probe beam passes through twice, the fundamental limit to detection sensitivity is found to be photon shot noise. More passes of the probe beam overcome this limitation. With a sensor of similar effective volume, 0.25 cm 3 , but 25 times more passes, the sensitivity is improved by an order of magnitude to 1.7 ± 0.2 fT/ √ Hz.

Self-Adaptive Loop for External-Disturbance Reduction in a Differential Measurement Setup

“…The optimization adapts an IIR filter with a transfer function in the form of Eq. (7). The best noise rejection is obtained applying eight nonzero coefficients among the parameter set.…”

A Non-Modulated Triaxial Magnetic Field Compensation Method for Spin-Exchange Relaxation-Free Magnetometer Based on Zero-Field Resonance

“…Equation (4) shows that the first order differential value of the zero-field resonance signal has a maximum only when the magnetic field along the three directions becomes zero simultaneously. Therefore, we can compensate the triaxial magnetic field by maximizing the first order differential value of the zero-field resonance.…”

“…The atomic magnetometer operating in the spin-exchange relaxation-free (SERF) regime is currently known as the most sensitive detector in the low frequency magnetic field. The high sensitivity of SERF magnetometers has broadened the application range from fundamental physics research [1], [2] and magnetic property tests [3], [4] to portable devices for magnetoencephalography (MEG) [5], [6]. It is operated with a high density of alkali atoms in extremely weak…”

Full-Field Terahertz Imaging at Kilohertz Frame Rates Using Atomic Vapor

“…Because atoms have well-known properties and give reproducible measurements that can easily be related to SI units, they are ideal candidates for use in a new generation of sensors in the growing field of quantum technologies [20]. For example, atom-based sensors have been used for precise measurements of magnetic fields [21,22] and gravity [23,24] and are beginning to be marketed and used in fields as diverse as biomedical sensing [25], geomagnetic [26], and defense applications [27]. A subclass of atom-based sensors includes those based upon Rydberg atoms, atoms that have been excited to a high principal quantum number n. It has been shown that Rydberg atoms are excellent sensors for weak electromagnetic fields in the radio-frequency, microwave, and THz ranges [28][29][30][31], as well as for trace gas detection [32].…”