arXiv subjects

Kevin Su

Publications and source records attributed to Kevin Su.

5 recordsLinked to original sources

arXiv2026

Electron Beam Profiling via Rydberg Electromagnetically Induced Transparency in Rubidium Vapor with Crossed Laser beams

We present an all-optical detection approach to determine the position and spatial profile of an electron beam based on quantum properties of alkali metal atoms. To measure the electric field, produced by an electron beam, we excite thermal rubidium atoms to a highly excited Rydberg state via a two-photon ladder transition and detect Stark shifts of Rydberg states by monitoring frequencies of the corresponding electromagnetically induced transparency (EIT) transmission peaks. We addressed several technical challenges in this approach. First, we use crossed laser beams to obtain spatial information about the electron beam position and geometry. Second, by pulsing the electron beam and using phase-sensitive optical detection, we separate the true electron beam electric signature from the parasitic electric fields due to photoelectric charges on the windows. Finally, we use a principle component analysis to further improve signal quality. We test this method to detect the current and to reconstruct a 2D profile of a 20 keV electron beam with currents ranging from 25 - 100 uA. While this technique provides less spatial resolution than fluorescence-based measurements, thanks to their speed and limited optical access requirements it can be useful for real-time non-invasive diagnostics of charged particle beams at accelerator facilities.

physics.atom-ph↗

arXiv2025

Electron beam characterization via fluorescence imaging of Rydberg states in atomic vapor

We demonstrate an all-optical, minimally invasive method for electron beam (e-beam) characterization using Rydberg electrometry. The e-beam passes through a dilute Rb vapor prepared in a quantum superposition of ground and Rydberg states that reduces resonant absorption in a narrow spectral region. Imaging the modifications of Rb fluorescence due to shifts in the Rydberg state from the e-beam electric field allows us to reconstruct e-beam width, centroid position, and current. We experimentally demonstrate this technique using a 20 keV e-beam in the range of currents down to 20 $\mu$A, and discuss technical challenges produced by environmental electric potentials in the detection chamber. Overall, we demonstrate the promising potential of such an approach as a minimally invasive diagnostic for charged particle beams.

physics.atom-ph↗

arXiv2024

Two-dimensional imaging of electromagnetic fields via light sheet fluorescence imaging with Rydberg atoms

The ability to image electromagnetic fields holds key scientific and industrial applications, including electromagnetic compatibility, diagnostics of high-frequency devices, and experimental scientific work involving field interactions. Generally electric and magnetic field measurements require conductive elements which significantly distort the field. However, electromagnetic fields can be measured without altering the field via the shift they induce on Rydberg states of alkali atoms in atomic vapor, which are highly sensitive to electric fields. Previous field measurements using Rydberg atoms utilized electromagnetically induced transparency to read out the shift on the states induced by the fields, but did not provide spatial resolution. In this work, we demonstrate that electromagnetically induced transparency can be spatially resolved by imaging the fluorescence of the atoms. We demonstrate that this can be used to image $\sim$ V/cm scale electric fields in the DC-GHz range and $\sim$ mT scale static magnetic fields, with minimal distortion to the fields. We also demonstrate the ability to image $\sim$ 5 mV/cm scale fields for resonant microwave radiation and measure standing waves generated by the partial reflection of the vapor cell walls in this regime. With additional processing techniques like lock-in detection, we predict that our sensitivities could reach down to nV/cm levels. We perform this field imaging with a spatial resolution of 160 $\mu$m, limited by our imaging system, and estimate the fundamental resolution limitation to be 5 $\mu$m.

physics.atom-ph↗

arXiv2020

Cluster Diffusing Shuffles

Unbiased shuffling algorithms, such as the Fisher-Yates shuffle, are often used for shuffle play in media players. These algorithms treat all items being shuffled equally regardless of how similar the items are to each other. While this may be desirable for many applications, this is problematic for shuffle play due to the clustering illusion, which is the tendency for humans to erroneously consider 'streaks' or 'clusters' that may arise from samplings of random distributions to be non-random. This thesis attempts to address this issue with a family of biased shuffling algorithms called cluster diffusing (CD) shuffles which are based on disordered hyperuniform systems such as the distribution of cone cells in chicken eyes, the energy levels of heavy atomic nuclei, the eigenvalue distributions of various types of random matrices, and many others which appear in a variety of biological, chemical, physical, and mathematical settings. These systems suppress density fluctuations at large length scales without appearing ordered like lattices, making them ideal for shuffle play. The CD shuffles range from a random matrix based shuffle which takes $O(n^3)$ time and $O(n^2)$ space to more efficient approximations which take $O(n)$ time and $O(n)$ space.

cs.SI↗

arXiv2019

VeriSFQ - A Semi-formal Verification Framework and Benchmark for Single Flux Quantum Technology

In this paper, we propose a semi-formal verification framework for single-flux quantum (SFQ) circuits called VeriSFQ, using the Universal Verification Methodology (UVM) standard. The considered SFQ technology is superconducting digital electronic devices that operate at cryogenic temperatures with active circuit elements called the Josephson junction, which operate at high switching speeds and low switching energy - allowing SFQ circuits to operate at frequencies over 300 gigahertz. Due to key differences between SFQ and CMOS logic, verification techniques for the former are not as advanced as the latter. Thus, it is crucial to develop efficient verification techniques as the complexity of SFQ circuits scales. The VeriSFQ framework focuses on verifying the key circuit and gate-level properties of SFQ logic: fanout, gate-level pipeline, path balancing, and input-to-output latency. The combinational circuits considered in analyzing the performance of VeriSFQ are: Kogge-Stone adders (KSA), array multipliers, integer dividers, and select ISCAS'85 combinational benchmark circuits. Methods of introducing bugs into SFQ circuit designs for verification detection were experimented with - including stuck-at faults, fanout errors, unbalanced paths, and functional bugs like incorrect logic gates. In addition, we propose an SFQ verification benchmark consisting of combinational SFQ circuits that exemplify SFQ logic properties and present the performance of the VeriSFQ framework on these benchmark circuits. The portability and reusability of the UVM standard allows the VeriSFQ framework to serve as a foundation for future SFQ semi-formal verification techniques.

cs.ET↗