Magnon dark modes and gradient memory

TL;DR

This paper demonstrates a dissipation-engineered magnon gradient memory system using yttrium iron garnet, enabling long-lived, multimode quantum memory by storing information in magnon dark modes that decouple from the cavity.

Contribution

It introduces a novel dissipation engineering method to realize magnon dark modes for long-lived quantum memory in hybrid systems.

Findings

Achieved non-Markovian magnon-cavity interactions.

Built a magnon gradient memory with long lifetime.

Enabled multimode quantum information storage.

Abstract

Extensive efforts have been expended in developing hybrid quantum systems to overcome the short coherence time of superconducting circuits by introducing the naturally long-lived spin degree of freedom. Among all the possible materials, single-crystal yttrium iron garnet has shown up very recently as a promising candidate for hybrid systems, and various highly coherent interactions, including strong and even ultra-strong coupling, have been demonstrated. One distinct advantage of these systems is that the spins are in the form of well-defined magnon modes, which allows flexible and precise tuning. Here we demonstrate that by dissipation engineering, a non-Markovian interaction dynamics between the magnon and the microwave cavity photon can be achieved. Such a process enables us to build a magnon gradient memory to store information in the magnon dark modes, which decouple from the microwave cavity and thus preserve a long life-time. Our findings provide a promising approach for developing long-lifetime, multimode quantum memories.