Extending the electron spin coherence time of atomic hydrogen by dynamical decoupling

Abstract

We study the electron spin decoherence of encapsulated atomic hydrogen in octasilsesquioxane cages induced by the ¹H and ²⁹Si nuclear spin bath. By applying the Carr–Purcell–Meiboom–Gill (CPMG) pulse sequence we significantly suppress the low-frequency noise due to nuclear spin flip-flops up to the point where a maximum T₂ = 56 μs is observed. Moreover, dynamical decoupling with the CPMG sequence reveals the existence of two other sources of decoherence: first, a classical magnetic field noise imposed by the ¹H nuclear spins of the cage organic substituents, which can be described by a virtual fluctuating magnetic field with the proton Larmor frequency, and second, decoherence due to anisotropic hyperfine coupling between the electron and the inner ²⁹Si spins of the cage.