In this book, hybrid systems based on yttrium-iron-garnet (YIG), three dimensional microwave cavity resonators, and superconducting transmon qubits, are investigated by continuous wave and pulsed microwave spectroscopy. Limitations to the magnetic linewidth in the quantum regime are identified and coherent exchange between a magnon and a superconducting qubit are demonstrated. Finally, a first step towards a strongly coupled hybrid system containing all three components is demonstrated.
In this book, hybrid systems based on yttrium-iron-garnet (YIG), three dimensional microwave cavity resonators, and superconducting transmon qubits, are investigated by continuous wave and pulsed microwave spectroscopy. Limitations to the magnetic linewidth in the quantum regime are identified and coherent exchange between a magnon and a superconducting qubit are demonstrated. Finally, a first step towards a strongly coupled hybrid system containing all three components is demonstrated.
Hybrid quantum systems have attracted much attention due to the fact that they combine the advantages of different physical subsystems. Cavity QED (cavity quantum electrodynamics) with magnons is a hybrid quantum systems that combines a YIG (Yttrium Iron Garnet) sphere and a 3D (three-dimensional) rectangular microwave cavity. Based on this hybrid photon-magnon system, we obtain an approximate analytic solution by the RWA (rotating wave approximation) with an ingenious transformation. After skillfully diagonalizing the Hamiltonian, we show that the Kerr-nonlinearity interactions could yield a negativity value of the Wigner function, periodic quadrature squeezing effects, antibunching property, and field nonclassicality in the magnon. Our work may stimulate the study of nonclassicality of photon-magnon coupling systems and its potential applications in quantum information processing.
We show that the hybrid magnon-photon bundle emission is possible to generate by employing a three-level Δ -type superconducting artificial atom. The single atom is dispersively coupled with two microwave cavities, one of which simultaneously couples to a yttrium iron garnet (YIG) sphere via the magnetic dipole interaction. Based on the virtual photon exchange, the indirect magnon-atom interaction is established with flexibly tunable coupling strength, thus leading to the consecutive emission of hybrid magnon-photon pairs. The super-Rabi oscillation and Purcell effect make such a hybrid bundle possible in the present three-level system, which is difficult to achieve in the two-level system. The present scheme may find potential applications in quantum information processing and quantum sensing technology. Published by the American Physical Society 2024
The implementation of quantum network made up of multiple nodes and channels needs to take advantage of hybrid quantum systems. So far, in the hybrid ferromagnet-superconductor quantum system, the establishment of the remote effective interactions based on the virtual photons exchange mediated by the microwave cavity mode has been experimentally confirmed, providing a physical basis for the implementation of the remote signal transfer from one node to another. In this work, we put forward a magnon-based hybrid quantum system consisting of two macroscopic spin subsystems [i.e., millimeter-diameter ferromagnetic yttrium-iron-garnet (YIG) spheres] and one transmon-type superconducting qubit, and show that the mechanism of the cavity-mediated remote magnon-mode intertalk is feasible for achieving microwave signal transfer, simultaneously accompanied by a transition from Poissonian to sub-Poissonian statistics. We find that by tuning the typical system parameters properly, even if there is a mismatch in magnon-mode frequencies or dissipation rates between the two YIG spheres, the microwave information transfer from one YIG sphere to another is still robust, where the signal output through another YIG sphere exhibits pronounced antibunching. In addition, the proposed hybrid quantum system possesses a robustness window against the dissipation rates of both the qubit and the two Kittel modes. The analytical calculations and numerical simulations are conducted under experimentally accessible conditions, and the consistency of the results attained by these two methods makes our research more credible. Physically, we notice that two conversion channels are opened. One channel comes from the linear coupling. The other is based on the nonlinear interaction, which also is the underlying mechanism responsible for nonclassical sub-Poissonian signal output.
Hybrid systems based on magnons in ferromagnetic materials, such as yttrium iron garnet, have achieved remarkable development in the last decade. These include the coupling of magnons to microwave and optical photons, superconducting qubits, phonons, spins, the center-of-mass motion of a ferromagnet, etc. Here, we review both the experimental and theoretical progress in this field, focusing on the generation of magnonic quantum states and their applications in a broad range of fields. Since the strong coupling is a prerequisite for achieving coherent quantum control of magnons and preparing magnonic quantum states, we start by introducing representative strong-coupling experiments in cavity magnonics, then review a series of protocols for creating various magnonic quantum states, such as Fock, cat, squeezed, and entangled states, and discuss their potential applications in macroscopic quantum studies, quantum information science, quantum sensing, magnonic quantum devices, dark matter detection, and so on. Finally, we summarize the review and give an outlook for the future study of quantum magnonics.
Inthe application of quantum information transduction with superconducting (SC) qubits, SC resonators play a phenomenal role in magnon-photon coupled systems. We present NbN (Tc= 10.8 K) superconducting microstrip resonators tailored for hybrid magnon-photon coupled systems. Our resonators exhibit remarkable coupling capability, enabling rigorous probing of magnon-photon interactions. With a fundamental frequency of 1.4 GHz and a second harmonic of 2.8 GHz, these resonators offer extensive frequency coverage, facilitating the identification and characterization of a wide spectral range. It exhibits a strong magnon-microwave photon coupling with a sphere of yttrium iron garnet (YIG). The average gyromagnetic ratio (γ/2π) and coupling strength (g/2π) achieved are 2.7 MHz/Oe and 11.14 MHz, respectively. The NbN SC resonators developed in this work address challenges associated with probing magnon-photon coupling in strong magnetic fields and are expected to serve as a unique platform for studying magnon-photon coupled hybrid devices.
We present a quantum theoretical framework that describes the simultaneous emergence of magnon- and photon lasing in a tripartite hybrid solid-state platform. The system integrates optically pumped nitrogen-vacancy (NV) centers, a magnetic yttrium-iron-garnet (YIG) microsphere, and a microwave (MW) cavity. Through a comprehensive analysis of the system's dynamics, we reveal the cooperative interactions that drive coherent-stimulated emission in both the magnonic (spin-wave) and photonic (electromagnetic) domains. The model outlines a scalable configuration in which NV centers, excited via optical pumping, couple efficiently to the magnon modes of the YIG sphere placed inside the microwave cavity. Numerical simulations based on experimentally accessible parameters confirm the feasibility of dual-domain lasing. This work advances the integration of photonic and magnonic platforms, opening new opportunities for quantum-enhanced sensing, low-power spintronics, and on-chip quantum information processing.