High-Sensitivity Atomic Magnetometry with Multi-Pass Cells in Earth’s Magnetic Field
September 2nd, 2019 VITO GIOVANNI LUCIVERO Princeton University

The development of sensitive and robust magnetic sensors in an unshielded environment, to detect biomedical signals as well as in many other magnetometry applications, present several challenges due to Earth’s static magnetic field and ambient field noise and gradients. I will describe two optically pumped magnetic gradiometers using 87Rb hot atoms and multi-pass probing via paramagnetic Faraday rotation. First, we use a compact sensor with a volume of 0.5 cm3, including multi-pass cell, optical components, fiberized heaters, a VCSEL laser and a quadrant photodiode to enable the gradiometer operation mode. We demonstrate a differential magnetic sensitivity of 14 fT/√Hz in a 50 µT bias field, Earth’s field magnitude, with an improvement of one to two orders of magnitude with respect to prior works in this regime. We characterize the gradiometer common mode rejection ratio and report quantum-noise-limited experimental sensitivity in the presence of quantum spin noise and atomic diffusion [3]. Secondly, I will describe design, calibration and optimization of a novel high-sensitivity intrinsic gradiometer using a V-shaped multi-pass cell. Here two 87Rb ensembles are polarized with opposite polarization resulting in out-of-phase free induction decay and a near-zero Faraday rotation despite of the high, optically induced, atomic polarization.

Seminar, September 2, 2019, 12:00. ICFO’s Seminar Room

Hosted by Prof. Morgan W. Mitchell