Fig. 2: The quantum sensing of free space RF signal.
From: Quantum enhanced radio detection and ranging with solid spins
a Optically detected magnetic resonance (ODMR) spectrum of NV center ensemble. The circles are experimental results. The solid line is the Lorentz fit. b The Rabi oscillation is visualized by initialization and detecting the spin state with a green laser (0.7 mW power). The pulse duration is \(\frac{{t}_{\det }}{2}\) (= 550 ns) for both the initializing and detecting. The dashed line indicates a perfect spin transition without decoherence and inhomogeneous broadening. High fluorescence emission means the spin state of ms = 0, while low emission rate represents the spin state of ms = ± 1. The error bars represent the standard error of measurements. c The photograph illustrated the center of nanowire-bowtie structure. d The distribution of RF field, which is imaged by detecting the spin state transition under continuous-wave RF and laser excitation. e Real time measurement of RF amplitude modulation with NV center ensemble. The amplitude of RF source is changed with a step of 0.95 nT. Each experimental data point is obtained by repeating the spin detection pulse sequence 2 × 105 times. Only the reference RF is turned on here, and the power is approximately 2.3 mW.
