Progress towards atomic magnetometry below room temperature.

Heather L. Partner, Brigette D. Black, J. M. Geremia

Zahraa Al-Baiaty, Felix A. Hahl, Sarath Raman Nair +6 more

High precision magnetometry is important for a range of applications from the monitoring of biologically generated magnetic fields (e.g. magnetoencephalography and magnetocardiography), to navigation in GPS denied environments, to the detection of gravitational waves. Diamond containing the negatively-charged nitrogen vacancy colour centre (NV-) has emerged as a powerful room-temperature sensing solution. Here we explore NV- centres as a laser medium for a new form of magnetometry: laser threshold magnetometry (LTM). LTM works by placing NV- inside an optical cavity and uses the coherent laser output as a potentially more sensitive readout channel than is possible using conventional (incoherent) optically detected magnetic resonance. Here we show progress towards LTM with diamond. We show twolaser excitation and stimulated emission in free space, and report progress towards diamond-cavity experiments. Our studies highlight the need for different NV- optimisation for laser applications, rather than those conventionally used for quantum information applications

Kasper Jensen, W. Wasilewski, Hanna Krauter +4 more

Guzhi Bao, Jun Chen, Ruiqi Wang +2 more

We demonstrate an atomic magnetometry using amplitude-modulated pumping and hyperfine repumping techniques in a paraffin-coated cell. By exploiting the constructive interference between spins polarized by the pump beam and an additional repump beam, we observe a three-fold increase in the amplitude of magnetic resonance, along with a reduction in linewidth by approximately two times. The implementation of the repump beam effectively narrows the linewidth, demonstrating successful suppression of spin-exchange relaxation. This reduction in relaxation rate, combined with the enhanced signal, significantly improves the sensitivity of the magnetometer. Consequently, our technique offers a promising approach for achieving SERF-like magnetometry with sub-fT-level sensitivity in Earth-field range and room-temperature environment.

Antonio A. Gentile, Raffaele Santagati, Sebastian Knauer +11 more

Optical readout from nanofabricated single NV centres is enhanced via Bayesian inference techniques, to demonstrate efficient magnetometry at room temperature conditions. We achieve experimentally Heisenberg-limited sensitivities O(100 nT s1/2), thus competing with state-of-art cryogenic set-ups.

Yujiro Eto, Mark Sadrove, Takuya Hirano