The Noise Measurement of Nitrogen Vacancy Center Correlations Below the Diffraction Limit in Diamond

Abstract

There has been growing interest in the research and development in the fields of quantum information science and quantum sensing. Solid-state quantum systems with electron-spins are some of the most promising candidates for the evolution of quantum-bits (qubits), specifically those associated with atom like impurities such as the Nitrogen Vacancy (NV) center. In this paper we study the readout noise affecting covariance measurements between separate NV centers under the sub-diffraction limit in order to further probe the behavior of NV centers and what information they can sense about their local environment. Our main aim is to observe whether NV centers that are in close proximity and subject to the same manipulation and readout techniques have measurable correlations. Efficient readout of individual electronic spins is essential for measurement and applications in quantum information processing and quantum metrology. Therefore, for NV centers, we convert the electronic spin state of the NV to a charge-state distribution and read out the charge state rather than the spin to improve spin readout efficiency such that we can study the correlation between NV centers to a high enough degree of accuracy to determine any relationship between the centers. In order to measure correlations to a high degree of accuracy, we experiment with different values of ionization (red) laser strength as well as ionization time to optimize experimental parameters to minimize readout noise.