arXiv subjects

Michael A. Viray

Publications and source records attributed to Michael A. Viray.

9 recordsLinked to original sources

arXiv2026

Profiling a Rydberg-Atom Electric Field Sensor for Off-Resonant Detection of Sub-100 MHz RF Signals

We present a Rydberg-Atom electric field sensor optimized to detect signals at sub-100 MHz carrier frequencies. The sensing setup employs a sapphire vapor cell that allows for detection of signals below 100~MHz -- typical vapor cells made of glass or quartz demonstrate strong screening of radio frequency (RF) signals in this frequency regime. Applied signals are detected by observing AC Stark shifts in the atomic vapor energy levels. As a test case for the commercial utility of this receiver, we perform our tests at several carrier frequencies in the Industrial, Scientific, and Medical (ISM) band. At each carrier frequency, we report sensitivity, minimum detectable field, and detectable electric-field dynamic range. We also present a routine for optimizing off-resonant signal detection by tuning experimental parameters such as Rydberg coupler laser detuning and RF local oscillator strength. This Python-based optimization routine, which can be used at any off-resonant carrier frequency, is shared on Github for others to use in their own investigations.

physics.atom-ph↗

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) $\mathrm{\frac{μV}{m \sqrt{Hz}}}$ at 300 MHz and characterize noise-equivalent fields in the ultra-low to very-low frequency (ULF-VLF) band.

physics.atom-ph↗

arXiv2023

Very-high- and ultrahigh- frequency electric field detection using high angular momentum Rydberg states

We demonstrate resonant detection of rf electric fields from 240 MHz to 900 MHz (very-high-frequency (VHF) to ultra-high-frequency (UHF)) using electromagnetically induced transparency to measure orbital angular momentum $L=3\rightarrow L'=4$ Rydberg transitions. These Rydberg states are accessible with three-photon infrared optical excitation. By resonantly detecting rf in the electrically small regime, these states enable a new class of atomic receivers. We find good agreement between measured spectra and predictions of quantum defect theory for principal quantum numbers $n=45$ to $70$. Using a super-hetrodyne detection setup, we measure the noise floor at $n=50$ to be $13\,\mathrm{μV/m/\sqrt{Hz}}$. Additionally, we utilize data and a numerical model incorporating a five-level master equation solution to estimate the fundamental sensitivity limits of our system.

physics.atom-ph↗

arXiv2022

Rydberg state engineering: A comparison of tuning schemes for continuous frequency sensing

On-resonance Rydberg atom-based radio-frequency (RF) electric field sensing methods remain limited by the narrow frequency signal detection bands available by resonant transitions. The use of an additional RF tuner field to dress or shift a target Rydberg state can be used to return a detuned signal field to resonance and thus dramatically extend the frequency range available for resonant sensing. Here we investigate three distinct tuning level schemes based on adjacent Rydberg transitions, which are shown to have distinct characteristics and can be controlled with mechanisms based on the tuning field frequency or field strength. We further show that a two-photon Raman feature can be used as an effective tuning mechanism separate from conventional Autler-Townes splitting. We compare our tuning schemes to AC Stark effect-based broadband RF field sensing and show that although the sensitivity is diminished as we tune away from a resonant state, it nevertheless can be used in configurations where there is a low density of Rydberg states, which would result in a weak AC Stark effect.

physics.atom-ph↗

arXiv2021

Measurement of DC and AC electric fields inside an atomic vapor cell with wall-integrated electrodes

We present and characterize an atomic vapor cell with silicon ring electrodes directly embedded between borosilicate glass tubes. The cell is assembled with an anodic bonding method and is filled with Rb vapor. The ring electrodes can be externally connectorized for application of electric fields to the inside of the cell. An atom-based, all-optical, laser-spectroscopic field sensing method is employed to measure electric fields in the cell. Here, the Stark effect of electric-field-sensitive rubidium Rydberg atoms is exploited to measure DC electric fields in the cell of $\sim$5 V/cm, with a relative uncertainty of 10%. Measurement results are compared with DC field calculations, allowing us to quantify electric-field attenuation due to free surface charges inside the cell. We further measure the propagation of microwave fields into the cell, using Autler-Townes splitting of Rydberg levels as a field probe. Results are obtained for a range of microwave powers and polarization angles relative to the cell's ring electrodes. We compare the results with microwave-field calculations. Applications are discussed.

physics.atom-ph↗

arXiv2021

Photoionization of $nS$ and $nD$ Rydberg atoms of Rb and Cs from the near-infrared to the ultraviolet spectral region

We present calculations of the photoionization (PI) cross sections of rubidium and cesium Rydberg atoms for light with wavelengths ranging from the infrared to the ultraviolet, using model potentials from [M. Marinescu, H. R. Sadeghpour, and A. Dalgarno, Phys. Rev. A 49, 982 (1994)]. The origins of pronounced PI minima are identified by investigating the free-electron wavefunctions. These include broad PI minima in the $nS$ to $εP$ PI channels of both Rb and Cs, with free-electron energy $ε$, which are identified as Cooper minima. Much narrower PI minima in the $nD$ to $εF$ channels are due to shape resonances of the free-electron states. We describe possible experimental procedures for measuring the PI minima, and we discuss their implications in fundamental atomic physics as well as in practical applications.

physics.atom-ph↗

arXiv2020

A magneto-optical trap with millimeter ball lenses

We present a magneto-optical trap (MOT) design based on millimeter ball lenses, contained within a metal cube of 0.75$^{\prime \prime}$ side length. We present evidence of trapping approximately $4.2\times 10^5$ of $^{85}$Rb atoms with a number density of $3.2\times 10^9$ atoms/cm$^{3}$ and a loading time of 1.3 s. Measurement and a kinetic laser-cooling model are used to characterize the atom trap design. The design provides several advantages over other types of MOTs: the laser power requirement is low, the small lens and cube sizes allow for miniaturization of MOT applications, and the lack of large-diameter optical beam pathways prevents external blackbody radiation from entering the trapping region.

physics.atom-ph↗

arXiv2020

Coulomb Expansion of Cold Non-Neutral Rubidium Plasma

We study the expansion of a cold, non-neutral ion plasma into the vacuum. The plasma is made from cold rubidium atoms in a magneto-optical trap (MOT) and is formed via ultraviolet photoionization. We employ time-delayed plasma extraction and imaging onto a position- and time-sensitive micro-channel plate detector to analyze the plasma. We report on the formation and persistence of plasma shock shells, pair correlations in the plasma, and external-field-induced plasma focusing effects. We also develop trajectory and fluid descriptions to model the data and to gain further insight. The simulations verify the formation of shock shells and correlations, and allow us to model time- and position-dependent density, temperature, and Coulomb coupling parameter, $Γ({\bf{r}},t)$. This analysis both reaffirms the presence of shock shells and verifies that the experimental plasma is strongly coupled.

physics.atom-ph↗

arXiv2019

Expansion Dynamics of Cold Non-Neutral Plasma

We study the expansion of a strongly coupled, non-neutral, and cylindrically arranged ion plasma into the vacuum. The plasma is made from cold rubidium atoms in a magneto-optical trap (MOT) and is formed via ultraviolet photoionization. Higher-density and lower-density plasmas are studied to exhibit different aspects indicative of strong coupling. In a higher-density regime, we report on the formation and persistence of plasma shock fronts, as well as external-field-induced plasma focusing effects. In the lower-density regime, conditions are ideal to observe the development and evolution of nearest-neighbor ion correlations, as well as geometry-induced asymmetries in the pair correlation function. Simulated results from a trajectory model and a fluid model are in good agreement with the measurements.

physics.atom-ph↗