Magnetically Tuned Continuous Transition from Weak to Strong Coupling in Terahertz Magnon Polaritons

Depending on the relative rates of coupling and dissipation, a light-matter coupled system is either in the weak- or strong-coupling regime. Here, we present a unique system where the coupling rate continuously increases with an externally applied magnetic field while the dissipation rate remains constant, allowing us to monitor a weak-to-strong coupling transition as a function of magnetic field. We observed a Rabi splitting of a terahertz magnon mode in yttrium orthoferrite above a threshold magnetic field of ~ 14 T. Based on a microscopic theoretical model, we show that with increasing magnetic field the magnons transition into magnon polaritons through an exceptional point, which will open up new opportunities for in situ control of non-Hermitian systems

Single Event Tolerance of X-ray SOI Pixel Sensors

We evaluate the single event tolerance of the X-ray silicon-on-insulator (SOI) pixel sensor named XRPIX, developed for the future X-ray astronomical satellite FORCE. In this work, we measure the cross-section of single event upset (SEU) of the shift register on XRPIX by irradiating heavy ion beams with linear energy transfer (LET) ranging from 0.022 MeV/(mg/cm2) to 68 MeV/(mg/cm2). From the SEU cross-section curve, the saturation cross-section and threshold LET are successfully obtained to be $3.4^{+2.9}_{-0.9}\times 10^{-10}~{\rm cm^2/bit}$ and $7.3^{+1.9}_{-3.5}~{\rm MeV/(mg/cm^2)}$, respectively. Using these values, the SEU rate in orbit is estimated to be $\lesssim$ 0.1 event/year primarily due to the secondary particles induced by cosmic-ray protons. This SEU rate of the shift register on XRPIX is negligible in the FORCE orbit.Comment: 9 pages, 5 figures, accepted for publication in JATI