Microwave cavity-free hole burning spectroscopy of Er$^{3+}$:Y$_2$SiO$_5$ at millikelvin temperatures

TL;DR

This study demonstrates the potential of Er$^{3+}$:Y$_2$SiO$_5$ crystal as a quantum memory for microwave photons by high-resolution spectroscopy and spectral hole burning at millikelvin temperatures, revealing key relaxation mechanisms.

Contribution

It introduces microwave cavity-free hole burning spectroscopy for Er$^{3+}$:Y$_2$SiO$_5$ at millikelvin temperatures, advancing understanding of its spin dynamics for quantum memory applications.

Findings

Identified electronic and hyperfine transitions in Er$^{3+}$:Y$_2$SiO$_5$

Studied spin relaxation processes at millikelvin temperatures

Determined main relaxation mechanisms

Abstract

Efficient quantum memory is of paramount importance for long-distance quantum communications, as well as for complex large-scale computing architectures. We investigate the capability of Er$^{3+}$:Y$_2$SiO$_5$ crystal to serve as a quantum memory for the travelling microwave photons by employing techniques developed for dense optical ensembles. In our efforts to do so, we have performed high-resolution microwave spectroscopy of Er$^{3+}$:Y$_2$SiO$_5$, where we identified electronic spin as well as hyperfine transitions. Furthermore, we have explored spectral hole burning technique and studied the spin relaxation process at millikelvin temperatures, determined the main relaxation mechanisms, which lay the groundwork for further studies of the topic.