Daniel Richardson | Searcharxiv

arXiv2026

Calibration of electric fields in low-frequency off-resonant Rydberg receivers

We present results on Rydberg atom-based electric field sensing in the range of 1 kHz - 300 MHz, using a three-photon Rydberg excitation scheme and a transverse electromagnetic (TEM) line waveguide to apply low-frequency rf fields to the cell. Measurements of low-frequency screening in quartz and sapphire vapor cells show excellent agreement with a phenomenological model of the effective vapor cell material properties based on an electrical 2-port measurement of the TEM line. We achieve a best noise-equivalent field of 106(4) $\mathrm{\frac{\mu V}{m \sqrt{Hz}}}$ at 300 MHz and characterize noise-equivalent fields in the ultra-low to very-low frequency (ULF-VLF) band.

physics.atom-ph↗

arXiv2018

Spontaneous Exact Spin-Wave Fractals in Magnonic Crystals

Exact fractals of nonlinear waves that rely on strong dispersion and nonlinearity and arise spontaneously out of magnetic media were observed for the first time. The experiments make use of a microwave to excite a spin wave in a quasi-one-dimensional magnonic crystal. When the power of the input microwave (Pin) is low, the output signal has a power-frequency spectrum that consists of a single peak. When Pin is increased to a certain level, the new side modes are generated through modulational instability (MI), resulting in a comb-like frequency spectrum. With a further increase in Pin, each peak in the frequency comb can evolve into its own, finer comb through the MI. As Pin is increased further, one can observe yet another set of finer frequency combs. Such a frequency-domain fractal manifests itself as multiple layers of amplitude modulation in the time-domain signal.

cond-mat.other↗