arXiv subjects

Xinyan Xiang

Publications and source records attributed to Xinyan Xiang.

3 recordsLinked to original sources

arXiv2025

Electric field diagnostics in a continuous rf plasma using Rydberg-EIT

We present a non-invasive spectroscopic technique to measure electric fields in plasma, leveraging large polarizabilities and Stark shifts of Rydberg atoms. Rydberg Stark shifts are measured with high precision using narrow-linewidth lasers via Electromagnetically Induced Transparency (EIT) of rubidium vapor seeded into a continuous, inductively coupled radio-frequency (rf) plasma in a few mTorr of argon gas. Without plasma, the Rydberg-EIT spectra exhibit rf modulation sidebands caused by electric- and magnetic-dipole transitions in the rf drive coil. With the plasma present, the rf modulation sidebands vanish due to screening of the rf drive field from the plasma interior. The lineshapes of the EIT spectra in the plasma reflect the plasma's Holtsmark microfield distribution, allowing us to determine plasma density and collisional line broadening over a range of pressures and rf drive powers. The work is expected to have applications in non-invasive spatio-temporal electric-field diagnostics of low-pressure plasma, plasma sheaths, process plasma and dusty plasma.

physics.atom-ph↗

arXiv2025

Filter circuit for suppression of electric-field noise in Rydberg-atom experiments

Rydberg atoms are widely employed in precision spectroscopy and quantum information science. To minimize atomic decoherence caused by dc Stark effect, the electric field noise at the Rydberg atom location should be kept below $\sim 10$ mV/cm. Here we present a simple yet effective electronic circuit, referred to as a clamp switch, that allows one to realize such conditions. The clamp switch enables precise low-noise electric field control while allowing application of fast high-voltage ionization pulses through the same electrode(s), enabling atom detection via electric-field ionization and electron or ion counting. We outline the circuit design and analyze its noise suppression performance for both small and large input signals. In application examples, we employ the clamp switch to reduce the spectral width and increase the signal strength of a Rydberg line by a factor of two, to estimate the electric-field noise in the testing chamber, and to perform electric-field calibration using Rydberg Stark spectroscopy. The clamp switch improves coherence times and spectroscopic resolution in fundamental and applied quantum science research with Rydberg atoms.

physics.atom-ph↗

arXiv2024

Quantum Diamond Microscope for Narrowband Magnetic Imaging with High Spatial and Spectral Resolution

The quantum diamond microscope (QDM) is a recently developed technology for near-field imaging of magnetic fields with micron-scale spatial resolution. In the present work, we integrate a QDM with a narrowband measurement protocol and a lock-in camera; and demonstrate imaging of radiofrequency (RF) magnetic field patterns produced by microcoils, with spectral resolution $\approx1$\,Hz. This RF-QDM provides multi-frequency imaging with a central detection frequency that is easily tunable over the MHz-scale, allowing spatial discrimination of both crowded spectral peaks and spectrally well-separated signals. The present instrument has spatial resolution $\approx2\,\mathrm{\mu m}$, field-of-view $\approx300\times300\,\mathrm{\mu m^2}$, and per-pixel sensitivity to narrowband fields $\sim{1}\,$nT$\cdot$Hz$^{-1/2}$. Spatial noise can be reduced to the picotesla scale by signal averaging and/or spatial binning. The RF-QDM enables simultaneous imaging of the amplitude, frequency, and phase of narrowband magnetic field patterns at the micron-scale, with potential applications in real-space NMR imaging, AC susceptibility mapping, impedance tomography, analysis of electronic circuits, and spatial eddy-current-based inspection.

physics.optics↗