A nuclear quantum memory enabled by strain

Coherent excitation of an ensemble of quantum objects offers the opportunity to realise robust entanglement generation and information storage in a quantum memory [1]. Thus far, interfacing with such a collective excitation deterministically has remained elusive owing to the difficulty of controlling a probe spin in the midst of a complex many-body system. In the strained atomic lattice of a semiconductor quantum dot, nuclear quadrupole effects generate an electron-nuclear interaction that can be engineered by driving the electron spin (Fig. 1a). By implementing an all-optical approach to access the individual quantised electronic-nuclear spin transitions, we have experimentally demonstrated coherent optical rotations of a single collective nuclear spin excitation corresponding to a spin wave called a nuclear magnon [2] (Fig. 1b).