Nitrogen vacancy (NV) centers in diamond have developed into a powerful solid-state platform for compact quantum sensors. Here, we compare different DC magnetometry methods like, e.g. continuous-wave optically detected magnetic resonance (CW-ODMR) and continuously excited (CE-) Ramsey measurements combined with lock-in detection to achieve high sensitivity using low optical excitation intensities. We achieve a sensitivity of 0.5 pT/Hz 1/2 while retaining mm sized sensor form. We also demonstrate a gradiometer set up which achieves pT sensitivity in unshielded environments. Combined with previous efforts on the diamond AC magnetometry, the diamond magnetometer is promising to perform as a full range magnetometer with pT-fT sensitivity and mm 3 sensing volume in ambient environments. I. INTRODUCTIONQuantum sensors have made extraordinary progress in sensitivity, precision, bandwidth, spatial and temporal resolution over the past years [1][2][3][4]. This has enabled highly precise

We propose and demonstrate a microwave-free vector magnetometer that simultaneously measures all Cartesian components of a magnetic field using nitrogen-vacancy (NV) ensembles in diamond. With fixed crystallographic axes inherent to the solid-state system, the present magnetometer leverages the level anticrossing in the triplet ground state at 102.4 mT, and is capable of measuring all three components of the magnetic field. Vector capability is proffered by modulating fields along the preferential NV axis and in the transverse plane and subsequent demodulation of the signal. This sensor exhibits a root mean square noise floor of ≈ 300 pT / √ Hz in all directions. The present technique is broadly applicable to both ensem-arXiv:1904.04361v1 [physics.app-ph]

Space trajectory design is usually addressed as an optimal control problem. Although it relies on the classic theory of optimal control, this branch possesses some peculiarities that led to the development of ad hoc techniques, which can be grouped into two categories: direct and indirect methods. This paper gives an overview of the principal techniques belonging to the direct methods. The technique known as “direct transcription and collocation” is illustrated by considering Hermite-Simpson, high-order Gauss-Lobatto, and pseudospectral methods. Practical examples are given, and several hints to improve efficiency and robustness are implemented.

We report a novel Cs-(129)Xe atomic spin gyroscope (ASG) with closed-loop Faraday modulation method. This ASG requires approximately 30 min to start-up and 110 °C to operate. A closed-loop Faraday modulation method for measurement of the optical rotation was used in this ASG. This method uses an additional Faraday modulator to suppress the laser intensity fluctuation and Faraday modulator thermal induced fluctuation. We theoretically and experimentally validate this method in the Cs-(129)Xe ASG and achieved a bias stability of approximately 3.25 °∕h.