A qubit links two millimeter-sized crystals in a quantum entanglement

This work proposes a detection scheme to verify the entanglement, indicating progress beyond creation toward proving quantum connection. The results suggest applications in exploring macroscopic quantum mechanics and testing decoherence theories. Gen Li and Jie Li, both affiliated with Zhejiang Key Laboratory of Micro-Nano Quantum Chips and Quantum Control and School of Physics at Zhejiang University, detailed a scheme using a superconducting qubit driven by a two-tone field to achieve this connection between the spheres’ magnon modes. This approach builds on recent demonstrations of cavity-mediated coupling between magnons in YIG spheres and superconducting qubits, establishing a platform for preparing macroscopic quantum states. The proposed entanglement relies on an effective magnonic two-mode squeezing interaction induced by precise control of qubit frequencies and the strengths of the applied driving fields. By adiabatically eliminating the microwave cavity mediating the interaction,…