High contrast quantum imaging with time-gated fluorescence detection

Optical detection of spin state has been widely used for the solid state spin qubit in the application of quantum information processing. The signal contrast determines the accuracy of quantum state manipulation, sensitivity of quantum sensing and resolution of quantum imaging. Here, we demonstrated a time-gated fluorescence detection method for enhancing the spin state signal contrast of nitrogen vacancy (NV) center in diamond. By adjusting the delay between time gate and the excitation laser pulse, we improved both the signal contrast and signal-to-noise ratio for NV spin detection. An enhancement ratio of 1.86 times was reached for the signal contrast. Utilizing the time-gated fluorescence detection, we further demonstrated a high contrast quantum imaging of nanoparticle's stray magnetic field. Without any additional manipulation of the quantum state, we expect that this method can be used to improve the performance of various applications with NV center.