AC magnetic field sensing using continuous-wave optically detected magnetic resonance of nitrogen-vacancy centers in diamond

Abstract

Nitrogen-vacancy (NV) centers in diamond are considered sensors for detecting magnetic fields. Pulsed optically detected magnetic resonance (ODMR) is typically used to detect AC magnetic fields; however, this technique can only be implemented after careful calibration that involves aligning an external static magnetic field, measuring continuous-wave (CW) ODMR, determining the Rabi frequency, and setting the microwave phase. In contrast, CW-ODMR can be simply implemented by continuous application of green CW laser and a microwave filed. In this letter, we report a method that uses NV centers and CW-ODMR to detect AC magnetic fields. Unlike conventional methods that use NV centers to detect AC magnetic fields, the proposed method requires neither a pulse sequence nor an externally applied DC magnetic field; this greatly simplifies the procedure and apparatus needed to implement this method. This method provides a sensitivity of 2.5 µT/ Hz at room temperature. Thus, this simple alternative to existing AC magnetic field sensors paves the way for a practical and feasible quantum sensor.

Novel Magnetic-Sensing Modalities with Nitrogen-Vacancy Centers in Diamond

“…At zero field, however, these transitions overlap, and shift equally with opposite sign in response to magnetic fields. Therefore, NV ensembles have been considered unusable as zero-field magnetometers [1], except in certain cases, for detecting ac fields in the presence of applied microwaves [70].…”

Control of all the transitions between ground state manifolds of nitrogen vacancy centers in diamonds by applying external magnetic driving fields

“…However, only two of these states are typically controlled, and the remaining state is not addressed using frequency selectivity. Recently, new schemes have been proposed to use all the three states in the ground state manifolds; they have demonstrated high-sensitivity magnetic fields sensing [32], high-sensitivity temperature sensing [24], and AC magnetic field sensing that does not require pulse control [33,34]. Moreover, the three levels of the NV centers can be used for a quantum memory of a superconducting qubits [35][36][37].Further developments are expected using the ∆-system [38].…”

Bandwidth analysis of AC magnetic field sensing based on electronic spin double-resonance of nitrogen-vacancy centers in diamond

“…Recently, our group has proposed and demonstrated novel technique of AC magnetic field sensing with the con-tinuous wave-ODMR (CW-ODMR), which dose not require the pulse control and high-speed measurements. This scheme is based on double resonance of sub-levels of spintriplet state of NV centers excited by simultaneous application of microwaves and radio-frequency (RF) fields [24]. The microwaves play a role of probing NV centers dressed by the RF fields which correspond to the target AC magnetic fields.…”

“…Such changes in the ODMR signals allows us to detect the AC magnetic fields. However, the AC magnetic field sensing with CW-ODMR was demonstrated with a fixed frequency that is resonant with the transition between |B〉 and |D〉 in [24]. For a practical purpose, it is important to determine the bandwith of the AC magnetic field sensor.…”

“…In our experiment, we apply external magnetic fields to obtain a clear spectrum while the previous demonstration of the AC magnetic field sensing with CW-ODMR was done without applied magnetic fields [24]. NV centers have four possible crystallographic axes, and we apply magnetic fields perpendicular to one of the crystallographic axes.…”