Electromagnetically induced transparency in an isotopically purified Nd$^{3+}$:YLiF$_4$ crystal

TL;DR

This paper reports the first observation of electromagnetically induced transparency in an isotopically purified Nd$^{3+}$:YLiF$_4$ crystal, revealing potential for solid-state quantum memories using off-resonant Raman interactions.

Contribution

It demonstrates EIT in Nd$^{3+}$:YLiF$_4$ with hyperfine levels near ZEFOZ points, highlighting superhyperfine coupling effects and advancing solid-state quantum memory research.

Findings

EIT observed in Nd$^{3+}$:YLiF$_4$ crystal with 35 MHz inhomogeneous broadening.

Transmission exhibits a comb-like structure due to superhyperfine coupling.

EIT occurs near ZEFOZ points where homogeneous linewidth is minimized.

Abstract

We report the first observation of electromagnetically induced transparency (EIT) in an isotopically purified Nd$^{3+}$:YLiF$_4$ crystal. This crystal demonstrates inhomogeneous broadening of optical transitions of about 35 MHz. EIT is observed in a symmetrical $\Lambda$-like system formed by two hyperfine sublevels of the ground state corresponding to a zero first order Zeeman (ZEFOZ) transition and a hyperfine sublevel of the excited state, which is not coupled to other ground-state sublevels. It is found that transmission of the probe field as a function of the two-photon detuning demonstrates a comb-like structure that can be attributed to superhyperfine coupling between Nd$^{3+}$ ions and fluorine nuclei. The observed structure can be resolved only in the vicinity of the ZEFOZ point where the homogeneous linewidth of the spin transition is sufficiently small. The results pave the way for implementing solid-state quantum memories based on off-resonant Raman interaction without spectral tailoring of optical transitions.