Coherent spin dynamics of ytterbium ions in yttrium orthosilicate

TL;DR

This study explores the spin coherence properties of ytterbium ions in yttrium orthosilicate, revealing long electron and nuclear spin coherence times suitable for quantum memory applications.

Contribution

It provides detailed measurements of electron and nuclear spin relaxation and coherence times of Yb$^{3+}$ ions in Y$_2$SiO$_5$, demonstrating their potential for quantum information storage.

Findings

Electron spin $T_2$ up to 73 μs at higher fields

Nuclear spin $T_1$ of 4.5 ms at 4.5 K

Dynamical decoupling extends coherence to over 0.5 ms

Abstract

We investigate the electron and nuclear spin coherence properties of ytterbium ($\mathrm{Yb}^{3+}$) ions with non-zero nuclear spin, within an yttrium orthosilicate (Y$_2$SiO$_5$) crystal, with a view to their potential application in quantum memories or repeaters. We find electron spin-lattice relaxation times are maximised at low magnetic field ($<100$ mT) where $g~\sim6$, reaching 5 s at 2.5 K, while coherence times are maximised when addressing ESR transitions at higher fields where $g\sim0.7$ where a Hahn echo measurement yields $T_2$ up to 73 $\mu$s. Dynamical decoupling (XY16) can be used to suppress spectral diffusion and extend the coherence lifetime to over 0.5 ms, close to the limit of instantaneous diffusion. Using Davies electron-nuclear-double-resonance (ENDOR), we performed coherent control of the $^{173}\mathrm{Yb}^{3+}$ nuclear spin and studied its relaxation dynamics. At around 4.5 K we measure a nuclear spin $T_1$ and $T_2$ of 4 and 0.35 ms, respectively, about 4 and 14 times longer than the corresponding times for the electron spin.