Quantum entanglement between two antiferromagnets in the microcavities

Mangons are newly developed as the qubits for quantum storage and information process. Here in this work, we focus on a hybrid quantum system containing two antiferromagnets, and the entanglement between magnons in the antiferromagnets could be generated through the strong coupling mediated by the same microwave mode. Moreover, we numerically simulated the process with the feasible parameters. And the influence of the system parameters, such as the magnon-photon coupling rate, the detuning, the bias magnetic field and the dissipation on the entanglement are discussed. By adjusting some of the experimental parameters, we show that two antiferromagnets can produce a large entanglement, which is a result that has not been found in other quantum systems before. Our findings may provide a potential platform for the completion of related quantum tasks in the future.

Quantum sensors for microscopic tunneling systems

The anomalous low-temperature properties of glasses arise from intrinsic excitable entities, so-called tunneling Two-Level-Systems (TLS), whose microscopic nature has been baffling solid-state physicists for decades. TLS have become particularly important for micro-fabricated quantum devices such as superconducting qubits, where they are a major source of decoherence. Here, we present a method to characterize individual TLS in virtually arbitrary materials deposited as thin films. The material is used as the dielectric in a capacitor that shunts the Josephson junction of a superconducting qubit. In such a hybrid quantum system the qubit serves as an interface to detect and control individual TLS. We demonstrate spectroscopic measurements of TLS resonances, evaluate their coupling to applied strain and DC-electric fields, and find evidence of strong interaction between coherent TLS in the sample material. Our approach opens avenues for quantum material spectroscopy to investigate the structure of tunneling defects and to develop low-loss dielectrics that are urgently required for the advancement of superconducting quantum computers.