In magnetometry using optically detected magnetic resonance of nitrogen vacancy (N-$V^{-}$) centers, we demonstrate speedup of more than 1 order of magnitude with a sequential Bayesian experiment design as compared with conventional frequency-swept measurements. The N-$V^{-}$ center is an excellent platform for magnetometry, with potential spatial resolution down to a few nanometers and demonstrated single-defect sensitivity down to nanoteslas per square root hertz. The N-$V^{-}$ center is a quantum defect with spin S = 1 and coherence time up to several milliseconds at room temperature. Zeeman splitting of the N-$V^{-}$ energy levels allows detection of the magnetic field via photoluminescence. We compare conventional N-$V^{-}$-center photoluminescence measurements that use predetermined sweeps of the microwave frequency with measurements using a Bayesian-inference method. In sequential Bayesian experiment design, the settings with maximum utility are chosen for each measurement in real time on the basis of the accumulated experimental data. Using this method, we observe an order of magnitude decrease in the N-$V^{-}$-center-magnetometry measurement time necessary to achieve a set precision.

• Machine learning
• Quantum information with hybrid systems
• Quantum information with solid state qubits
• Quantum sensing
• Spintronics
• Nitrogen vacancy centers in diamond
• Bayesian methods
• Optically detected magnetic resonance