Optical and spin coherence properties of Rb atoms in solid neon for magnetic field sensing
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Authors
Dargyte, Ugne
Issue Date
2023
Type
Dissertation
Language
Keywords
Alternative Title
Abstract
In recent years, interest has emerged in solid-state electron spin systems for magnetic field sensing and imaging with nanoscale spatial resolution. The goal is to detect and resolve a single nuclear spin. A significant application for such a spatial resolution is the imaging of complex biological molecules. Nitrogen-vacancy centers in diamond are one of the leading candidates for this goal. Single-nuclear spin imaging was achieved using a C-13 nuclear spin bath in bulk diamond. Electron spins on the surface of diamond, however, cause decoherence and make imaging of nuclear spins outside of the host matrix challenging.We propose a different type of magnetic field sensor utilizing a matrix isolation system. Alkali atoms implanted in rare-gas matrices have been proposed for quantum sensing, fundamental physics measurements, and dark matter detection. Prior work shows that the electron spin state of alkali atoms in the inert gas matrix can be optically polarized, read out, and coherently manipulated. The matrix can be doped at high sensor densities of 10^18 cm^(−3). Ultralong spin coherence lifetimes have been achieved using magnetic resonance dynamic decoupling sequences. In this dissertation, we discuss the optical and spin coherence properties of Rb atoms implanted in solid neon. These properties are relevant for using the Rb atoms as quantum sensors of magnetic fields. We demonstrate that the Rb ^2S_1/2 ground spin state can be optically polarized using circularly polarized light and read out using circular dichroism. Using a radiofrequency magnetic field, the electron spin state can be coherently manipulated. The T2^* ensemble dephasing time is on the order of µs. It is dominantly limited by inhomogenenous broadening caused by electrostatic-like interactions with the host matrix. Magnetic resonance pulse sequences greatly extend the coherence time T2 by decoupling the Rb spins from the environment. Using the alternating-phase Carr-Purcell (APCP) sequence to decouple from low frequency magnetic noise, we achieve ultralong spin coherence lifetimes of 0.1s. With the use of the APCP sequence we can take a nuclear magnetic resonance spectrum of the sample. In this spectrum, we detect the precession of neighboring Ne-21 nuclear spin in the matrix using the Rb ensemble. Because the nuclear spins in the matrix are essentially unpolarized, the sensing is done by individual Rb atoms of their nearest-neighbor Ne-21. This demonstrates the necessary sensitivity to detect a single nuclear spin. These results are promising for using single Rb atoms trapped in solid neon as quantum sensors. Particularly, molecules of interest can be co-implanted alongside the sensor atom inside the host matrix, eliminating problems caused by surface noise.