We describe a single beam compact spin exchange relaxation free (SERF) magnetometer whose configuration is simple and compatible with the silicon-glass bonding micro-machining method. Due to the small size of the vapor cell utilized in a miniature atomic magnetometer, the wall relaxation could not be neglected. In this study we show that Ne buffer gas is more efficient than that of the other typically utilized gas species such as nitrogen and helium for wall relaxation reduction theoretically and experimentally. 3 Amagats (1 Amagat=2.69×10¹⁹/cm³) Ne gas is filled in the vapor cell and this is the first demonstration of a Cs-Ne SERF magnetometer. In order to reduce the laser amplitude noise and the large background detection offset, which is reported to be the main noise source of a single beam absorption SERF magnetometer, we developed a laser power differential method and a factor of approximately two improvement of the power noise suppression has been demonstrated. In order to reduce the power consumption of the magnetometer, the Cs based atomic magnetometer is studied. We did an optimization of the magnetometer and a sensitivity of 23fT/Hz^1/2@100Hz has been achieved. This is the first demonstration of a single beam Cs based SERF magnetometer.

Magnetic sensing based on nitrogen-vacancy (NV) center ensembles provides unique signal-to-noise ratio and sensitivity for physical and biological measurements at room temperature. However, inhomogeneous microwave (MW) coupling with NV ensembles and different field projections onto the NV axes lead to nonsynchronous spin dephasing and pose severe challenges to magnetic sensing. In this paper, we experimentally investigated the impact of the MW field uniformity on the DC magnetic sensing based on NV ensembles. We obtained different MW field uniformity between 42% and 93% in the same direction using a square split ring resonator. The uniformity and direction of the MW field was mapped using a wide-field magnetic imaging system. The magnetic sensing with the MW frequency modulation technology confirmed the consistence between the theoretical analysis and experimental results. The sensitivity was enhanced by nearly seven times with the best MW field uniformity. Our study can promote the further application and development of magnetic sensing devices based on solid-state spin ensembles.

Recently, perfect optical vortexes (POVs) have attracted substantial attention, because they have an orbital angular momentum (OAM) and the beam diameter is independent of the topological charges. There are numerous innovative results that have been found by modulating the POV optical field. However, methods for controlling the arbitrary parameters of POV are lacking. In this paper, we use the optical pen to overcome this problem. The optical pen is a high-precision optical field modulation method construction based on the relationship between the optical path difference and phase. Based on this method, we have achieved POV arrays with controllable arbitrary parameters in free space, including the spatial position, numbers, topological charges, beam diameter, and amplitude. This work can be applied not only in the fields of optical tweezers, particle manipulation, and super-resolution microscopic imaging, but also will promote the development of optical communication, quantum information coding, and so on.

Experimental feasibility of potential quantum sensing and computing applications based on the oxygen-vacancy defect (V_BO_N center) in cubic boron nitride (c-BN) is theoretically predicted by means of first-principles calculations. The proposed V_BO_N center consisting of a boron vacancy (V_B) and an adjacent substitutional oxygen (O_N) is a plausible qubit candidate, which is isoelectronic to the NV⁻ center in diamond. We found that the neutral paramagnetic V_BO_N center is spin-triplet and exists mainly in p-type c-BN. The results demonstrate that the zero-field splitting of the neutral V_BO_N center in the ground state falls within the microwave range and has a value of approximately 2980 MHz. Furthermore, the neutral V_BO_N center hyperfine interactions in the ground state are determined to be in the tens of MHz. It is anticipated that our results will pave the way for the neutral V_BO_N center acting as a scalable platform for implementing quantum information processing, sensing, and beyond.

We proposed an annular microstrip-line resonator (AMLR) to provide a broadband, circularly polarized and uniform microwave field for state manipulation of negatively charged nitrogen-vacancy (NV^–) center ensembles in order to achieve wide magnetic field detection range and large area microwave synchronous manipulation in miniaturized magnetic sensing devices. The bandwidth of the designed AMLR was 410 MHz when the input return losses was -10dB. With the designed bandwidth, a magnetic field detection range of 292 G was achieved based on the NV^– center ensembles. The relationship between the direction of the magnetic field and the phase of the source signal indicated that the generated microwave field of AMLR was circularly polarized. Furthermore, the magnetic field magnitude homogeneity is higher than the parallel-microstrip-lines resonator (PMLR) and the intersected-microstrip-lines resonator (IMLR), and the magnetic field magnitude of AMLR had a difference of 0.012 G in the center of a 1×1 mm² area. The AMLR has a great potential in magnetic field detection, temperature and pressure detection, which is useful for quantum applications with NV^– center ensembles in diamond.