Enhanced spin coherence of rubidium atoms in solid parahydrogen

Alkali atoms trapped in solid parahydrogen are optically addressable and have excellent spin coherence properties. They retain these properties at high spin densities, making them a promising platform for applications such as atomic magnetometry in the solid phase. We have identified the physical mechanism that limits the ensemble T$_2^*$ as electrostatic in nature, and are able to achieve significantly longer T$_2^*$ times by using nonclassical spin superposition states. By contrast, we find the spin-echo T$_2$ is limited by interactions that are magnetic in nature. Progress towards identifying the source of this magnetic decoherence will be discussed.