Magnon dark modes and gradient memory

• Published in: Nature communications Vol. 6; no. 1; p. 8914
• Main Authors: Zhang, Xufeng, Zou, Chang-Ling, Zhu, Na, Marquardt, Florian, Jiang, Liang, Tang, Hong X.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 16.11.2015; Nature Publishing Group; Nature Pub. Group
• Subjects: 639/301/119/1003; 639/766/483/481; Humanities and Social Sciences; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms9914

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 recently as a promising candidate for hybrid systems, and various highly coherent interactions, including strong and even ultrastrong coupling, have been demonstrated. One distinct advantage in these systems is that spins form 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 lifetime. Our findings provide a promising approach for developing long-lifetime, multimode quantum memories. Yttrium iron garnet is a ferrimagnetic insulator which demonstrates robust photon-spin coupling in hybrid microwave cavity systems. Here, the authors demonstrate a magnon gradient memory based on the dark modes of a strongly-coupled system of multiple yttrium iron garnet spheres.