Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userDetermining the Angle-of-Arrival of an Radio-Frequency Source with a Rydberg Atom-Based Sensor
86
0
0.0
(
0
)
Added by
Christopher Holloway
Publication date
2021
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
In this work, we demonstrate the use of a Rydberg atom-based sensor for determining the angle-of-arrival of an incident radio-frequency (RF) wave or signal. The technique uses electromagnetically induced transparency in Rydberg atomic vapor in conjunction with a heterodyne Rydberg atom-based mixer. The Rydberg atom mixer measures the phase of the incident RF wave at two different locations inside an atomic vapor cell. The phase difference at these two locations is related to the direction of arrival of the incident RF wave. To demonstrate this approach, we measure phase differences of an incident 19.18 GHz wave at two locations inside a vapor cell filled with cesium atoms for various incident angles. Comparisons of these measurements to both full-wave simulation and to a plane-wave theoretical model show that these atom-based sub-wavelength phase measurements can be used to determine the angle-of-arrival of an RF field.
rate research
Read More
We present a self-calibrating, SI-traceable broadband Rydberg-atom-based radio-frequency (RF) electric field probe (the Rydberg Field Probe or RFP) and measurement instrument (Rydberg Field Measurement System or RFMS). The RFMS comprises an atomic RF field probe (RFP), connected by a ruggedized fiber-optic patch cord to a portable mainframe control unit with a software interface for RF measurement and analysis including real-time field readout and RF waveform visualization. The instrument employs electromagnetically induced transparency (EIT) readout of spectral signatures from RF-sensitive Rydberg states of an atomic vapor for continuous, pulsed, and modulated RF field measurement. The RFP exploits resonant and off-resonant Rydberg-field interactions to realize broadband RF measurements at frequencies ranging from ~10 MHz to sub-THz over a wide dynamic range. The RFMS incorporates an RF-field-free atomic reference and a laser-frequency tracker to ensure reliability and accuracy of the RF measurement. We characterize the RFP and measure polar field and polarization patterns of the RFP at 12.6 GHz RF in the far-field of a standard gain horn antenna. Measurements at 2.5 GHz are also performed. Measured patterns are in good agreement with simulations. A detailed calibration procedure and uncertainty analysis are presented that account for deviations from an isotropic response over a $4pi$ solid angle, arising from dielectric structures external to the atomic measurement volume. Contributions to the measurement uncertainty from the fundamental atomic measurement method and associated analysis as well as material, geometry, and hardware design choices are accounted for. A calibration (C) factor is used to establish absolute-standard SI-traceable calibration of the RFP. Pulsed and modulated RF field measurement, and time-domain RF-pulse waveform imaging are also demonstrated.
Rydberg atom-based electrometry enables traceable electric field measurements with high sensitivity over a large frequency range, from gigahertz to terahertz. Such measurements are particularly useful for the calibration of radio frequency and terahertz devices, as well as other applications like near field imaging of electric fields. We utilize frequency modulated spectroscopy with active control of residual amplitude modulation to improve the signal to noise ratio of the optical readout of Rydberg atom-based radio frequency electrometry. Matched filtering of the signal is also implemented. Although we have reached similarly, high sensitivity with other read-out methods, frequency modulated spectroscopy is advantageous because it is well-suited for building a compact, portable sensor. In the current experiment, $sim 3 mu V cm^{-1}Hz^{-1/2}$ sensitivity is achieved and is found to be photon shot noise limited.
An electrically-controllable, solid-state, reversible device for sourcing and sinking alkali vapor is presented. When placed inside an alkali vapor cell, both an increase and decrease of the rubidium vapor density by a factor of two are demonstrated through laser absorption spectroscopy on 10 to 15 s time scales. The device requires low voltage (5 V), low power (<3.4 mW peak power), and low energy (<10.7 mJ per 10 s pulse). The absence of oxygen emission during operation is shown through residual gas analysis, indicating Rb is not lost through chemical reaction but rather by ion transport through the designed channel. This device is of interest for atomic physics experiments and, in particular, for portable cold-atom systems where dynamic control of alkali vapor density can enable advances in science and technology.
We realize and model a Rydberg-state atom interferometer for measurement of phase and intensity of radio-frequency (RF) electromagnetic waves. A phase reference is supplied to the atoms via a modulated laser beam, enabling atomic measurement of the RF waves phase without an external RF reference wave. The RF and optical fields give rise to closed interferometric loops within the atoms internal Hilbert space. In our experiment, we construct interferometric loops in the state space ${ 6P_{3/2}, 90S_{1/2}, 91S_{1/2}, 90P_{3/2} }$ of cesium and employ them to measure phase and intensity of a 5 GHz RF wave in a room-temperature vapor cell. Electromagnetically induced transparency on the $6S_{1/2}$ to $6P_{3/2}$ transition serves as an all-optical interferometer probe. The RF phase is measured over a range of $pi$, and a sensitivity of 2 mrad is achieved. RF phase and amplitude measurements at sub-millimeter optical spatial resolution are demonstrated.
This work presents an experimental protocol conceived to determine the vibrational distribution of barium monofluoride molecules seeded in a supersonic beam of argon. Here, as in many cases, the detection signal is related to the number of molecules by an efficiency involving several parameters that may be difficult to determine properly. In particular, this efficiency depends on the vibrational level of the detected molecules. Our approach avoids these complications by comparing different detection signals generated by different vibrational excitations. Such an excitation is made possible by the use of a broadband optical source that depletes a specific vibrational level whose population is redistributed in the other levels.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
