Hole burning experiments and modeling in erbium-doped silica glass fibers down to millikelvin temperatures: evidence for ultra-long population storage

TL;DR

This study uses spectral hole burning at ultra-low temperatures to analyze spin dynamics in erbium-doped fibers, revealing ultra-long population storage times and modeling multiple relaxation mechanisms relevant for quantum memory.

Contribution

It provides a comprehensive model of spin relaxation in erbium-doped fibers across all observed decay components at millikelvin temperatures, highlighting their potential for quantum memory.

Findings

Achieved spin lifetimes over 9 hours at 7 mK.

Identified three decay components with distinct mechanisms.

Modeled spin dynamics with a unified set of mechanisms.

Abstract

We use spectral hole burning to investigate spin dynamics within the electronic Zeeman sublevels of the ground state of the erbium ions in erbium-doped fibers (EDF). Conducted at ultra-low temperatures and under varying magnetic fields, our study reveals distinct changes in spin relaxation dynamics across different conditions. We identified three decay components at approximately 7 mK, with one achieving spin lifetimes of over 9 hours under optimal conditions, while two components were observed at higher temperatures. The fairly stable relative weights of the decay components across conditions suggest distinct ion populations contributing to the observed relaxation dynamics. While earlier studies struggled to account for all decay components at higher temperatures, our approach successfully models spin dynamics across all observed decay components, using a consistent set of underlying mechanisms, including spin flip-flop interactions, direct coupling to two-level systems, and Raman-type processes, and distinguishes the decay components by the strengths with which these mechanisms contribute. These results suggest EDFs' potential as a promising candidate for quantum memory applications, with further room for optimization.