Hybrid quantum systems based on magnonics

Abstract

Engineered quantum systems enabling novel capabilities for communication, computation, and sensing have blossomed in the last decade. Architectures benefiting from combining distinct and complementary physical quantum systems have emerged as promising platforms for developing quantum technologies. A new class of hybrid quantum systems based on collective spin excitations in ferromagnetic materials has led to the diverse set of experimental platforms which are outlined in this review article. The coherent interaction between microwave cavity modes and collective spin-wave modes is presented as the backbone of the development of more complex hybrid quantum systems. Indeed, quanta of excitation of the spin-wave modes, called magnons, can also interact coherently with optical photons, phonons, and superconducting qubits in the fields of cavity optomagnonics, cavity magnomechanics, and quantum magnonics, respectively. Notably, quantum magnonics provides a promising platform for performing quantum optics experiments in magnetically-ordered solid-state systems. Applications of hybrid quantum systems based on magnonics for quantum information processing and quantum sensing are also outlined briefly.

Entangling two magnon modes via magnetostrictive interaction

“…Therefore, preparing macroscopic quantum states is a key step to test those decoherence theories in macroscopic scale. Furthermore, the magnon entangled states can be applied to the quantum information processing based on magnonic systems [10], and can also be used for creating entangled states of microwave fields, e.g. by coupling each magnon mode to a microwave cavity and utilizing their beamsplitter (state-swap) interaction.…”

“…Owing to their high spin density (several orders of magnitude larger than those of previous spin ensembles) and low dissipation rate, in recent years the strong [1][2][3][4][5][6] and ultrastrong [7,8] coupling between the Kittel mode [9] in the YIG sphere and the microwave cavity photons have been realized leading to cavity-magnon polaritons. This strong coupling offers a possibility to enable coherent information transfer between drastically different information carriers, and thus may find potential applications in quantum information processing, especially when the system becomes hybrid [10], such as by coupling magnons to a superconducting qubit [11,12], to phonons [13,14], or to both microwave and optical photons [15]. Furthermore, various interesting phenomena have been explored in the system of cavity-magnon polaritons, such as the observation of magnon gradient memory [16], the exceptional point [17,18], manipulation of distant spin currents [19], and bistability [20], to name but a few.…”

Steering between level repulsion and attraction: broad tunability of two-port driven cavity magnon-polaritons

“…The phenomena of (strong) coupling of magnons-the associated quanta of collective spin wave excitations-to microwave cavity photons resulting in cavity magnon-polaritons (CMPs) has been the subject of numerous works in the past few years [1][2][3][4][5][6][7][8][9]. The ability to couple magnons to different physical systems, through magnetooptical [10][11][12] to optical, or by magnetostrictive interaction to mechanical [13] and cavity photons simultaneously makes CMPs highly interesting for various applications [8]. For instance, it allows for a bidirectional conversion of microwaves to optical light [14], or coupling magnons with superconducting circuits, i.e.…”

High-efficiency triple-resonant inelastic light scattering in planar optomagnonic cavities

“…A key difficulty for achieving efficient magnon-assisted microwave-to-optical transduction is the inherently weak coupling between optical photons and microwave-triggered magnonic excitations, termed optomagnonic interaction, hindering among others the long-awaited optical interfacing of superconducting qubits [1][2][3][4][5]. To this end, judiciously designed dielectric structures, which include magnetic materials, capable of simultaneously confining light (optical photons) and spin waves (magnons) in the same region of space, so-called optomagnonic cavities, are currently being actively studied as they might potentially form ideal hosts for attaining increased optomagnonic interactions.…”