arXiv subjects

Jinwei Rao

Publications and source records attributed to Jinwei Rao.

6 recordsLinked to original sources

arXiv2026

Weak Magnetic Sensing via Floquet Driving in an Active Cavity Magnon Coupled System

While significant advancements have been made in weak magnetic field detection, conventional high-sensitivity techniques are often limited by requirements for cryogenic operation or bulky setups. In this work, we develop a sensitive alternating magnetic field sensor based on a coupled system of an active microwave cavity and yttrium iron garnet (YIG), with the components implemented on printed circuit boards (PCBs). By introducing electrically tunable gain to compensate for cavity losses, we substantially improve both the quality factor and the signal intensity. Under the coupled system, Floquet modulation is induced by the alternating magnetic field, allowing for weak field detection by driving a specific hybrid mode and measuring the resulting Floquet sidebands. This miniaturized device operates at room temperature, achieving a detection limit of 121 pT/\sqrt{Hz}.

cond-mat.mes-hall↗

arXiv2025

Ultrasensitive Magnetometer based on Cusp Points of the Photon-Magnon Synchronization Mode

Ultrasensitive magnetometers based on spin resonances have led to remarkable achievements. However, the gyromagnetic ratios of these spin resonances that determine the responsivity of magnetometers to weak magnetic fields are inherently constrained by the Land$\acute{e}$ g-factor of particles, such as the electron, with a constant gyromagnetic ratio of $γ_e=2π\times28$ GHz/T. Here, we demonstrate an ultrasensitive magnetometer based on the cusp point (CP) of photon-magnon synchronization modes (PMSMs). The PMSM's gyromagnetic ratio at the CP is enhanced to $37γ_e$ and further amplified to $236γ_e$ by utilizing the sixth-order oscillating mode of the PMSM. Moreover, the emission linewidth of the PMSM can be reduced to 0.06 Hz, resulting in excellent sensitivity to weak magnetic fields. These outstanding properties position our magnetometer to potentially achieve superior sensitivity to conventional magnetometers. Our work introduces a cost-effective prototype for the next generation of magnetometry, and may advance scientific research and technologies that rely on ultrasensitive magnetic field detection.

cond-mat.mes-hall↗

arXiv2024

Time-Varying Strong Coupling and Its Induced Time Diffraction of Magnon Modes

Time-varying media break the temporal translation symmetry of wave propagation in materials, enabling advanced wave manipulations. However, this novel phenomenon has been rarely explored in magnonic systems due to the significant challenge of achieving a sudden and prominent change in magnon dispersion within materials. Here, we construct a time-varying strong coupling between two magnon modes, and observe a change in the beats of Rabi-like oscillations near the pulse edges. Using a frequency-comb spectroscopy technique developed in this work, we characterize the frequency conversion of magnon modes induced by the time-varying strong-coupling effect. Moreover, we construct time slits with adjacent time interfaces and demonstrate, for the first time, the double-slit time diffraction of magnon modes, analogous to the well-known Young's double-slit experiment. These findings rely solely on the time-varying strong magnon coupling, independent of device reconfiguration. Our results open avenues for applications such as all-magnetic mixers or on-chip GHz sources.

cond-mat.mes-hall↗

arXiv2023

Meter-scale strong coupling between magnons and photons

We experimentally realize a meter-scale strong coupling effect between magnons and photons at room temperature, with a coherent coupling of 20 m and a dissipative coupling of 7.6 m. To this end, we integrate a saturable gain into a microwave cavity and then couple this active cavity to a magnon mode via a long coaxial cable. The gain compensates for the cavity dissipation, but preserves the cavity radiation that mediates the indirect photon-magnon coupling. It thus enables the long-range strong photon-magnon coupling. With full access to traveling waves, we demonstrate a remote control of photon-magnon coupling by modulating the phase and amplitude of traveling waves, rather than reconfiguring subsystems themselves. Our method for realizing long-range strong coupling in cavity magnonics provides a general idea for other physical systems. Our experimental achievements may promote the construction of information networks based on cavity magnonics.

quant-ph↗

arXiv2023

Control of the magnon-polariton hybridization with a microwave pump

Pump-induced magnon modes (PIMs) are recently discovered elementary excitations in ferrimagnets that offer significant tunability to spin dynamics. Here, we investigate the coupling between a PIM and cavity magnon polaritons (CMPs) by driving a cavity magnonic system away from equilibrium with a microwave pump. In our experiment, the Walker mode simultaneously couples with the PIM and cavity photons and thus combines two strongly coherent coupling processes in a single cavity structure. Such a PIM-CMP hybridization system acquires complementary properties from both the PIM and CMPs, allowing it to be freely manipulated by the magnetic field, the pump power and the pump frequency. These coherent manipulations exhibit unique behaviors beyond the intrinsic properties limited by the material nature and electromagnetic boundary conditions, thereby creating opportunities for extending the control of hybrid devices.

cond-mat.mes-hall↗

arXiv2023

Giant Enhancement of Magnonic Frequency Combs by Exceptional Points

With their incomparable time-frequency accuracy, frequency combs have significantly advanced precision spectroscopy, ultra-sensitive detection, and atomic clocks. Traditional methods to create photonic, phononic, and magnonic frequency combs hinge on material nonlinearities which are often weak, necessitating high power densities to surpass their initiation thresholds, which subsequently limits their applications. Here, we introduce a novel nonlinear process to efficiently generate magnonic frequency combs (MFCs) by exploiting exceptional points (EPs) in a coupled system comprising a pump-induced magnon mode and a Kittel mode. Even without any cavity, our method greatly improves the efficiency of nonlinear frequency conversion and achieves optimal MFCs at low pump power. Additionally, our novel nonlinear process enables excellent tunability of EPs using the polarization and power of the pump, simplifying MFC generation and manipulation. Our work establishes a synergistic relationship between non-Hermitian physics and MFCs, which is advantages for coherent/quantum information processing and ultra-sensitive detection.

cond-mat.mes-hall↗