Fig. 4. Room-temperature quantum sensing.
a, Contrast of OADF-based spin readout as a function of time after the onset of the 912-nm laser pulse for the Tx–Tz (purple) and the Ty–Tz (blue) transition. b, ODMR in aqueous solution at various magnetic fields. The red points indicate the frequencies of the field sensing experiment in c. c, DC magnetic-field sensing operating at a bias field of 36.5 mT by measuring the difference in the ODMR contrast defined as CT = [PLsig(ωa) − PLsig(ωb)/PLback]. The measurement is performed at the two frequencies ωa = (2π) × 3.54 GHz and ωb = (2π) × 3.43 GHz indicated in b. PLsig(ω), the OADF signal at a microwave frequency (ω); PLback, the OADF signal in the absence of a microwave drive. Panels a–c are measured at room temperature.