Rydberg quantum sensors are sensitive to radio-frequency fields across an ultra-wide frequency range spanning megahertz to terahertz electromagnetic waves resonant with Rydberg atom dipole transitions. Here, we demonstrate an atomic millimeter-wave heterodyne receiver employing continuous-wave lasers stabilized to an optical frequency comb. We characterize the atomic receiver in the W-band at a signal frequency of f = 95.992 512 GHz and demonstrate a sensitivity of 7.9 μV/m/Hz with a linear dynamic range in power greater than 70 dB. We develop frequency selectivity metrics for atomic receivers and demonstrate their use in our millimeter-wave receiver, including signal rejection levels at signal frequency offsets Δf/f = 10−4, 10−5, and 10−6; 3, 6, 9, and 12-dB bandwidths; filter roll-off; and shape factor analysis. Our work represents an important advance toward future studies and applications of atomic receiver science and technology in weak millimeter-wave and high-frequency signal detection.
Rydberg quantum sensors are sensitive to radio-frequency fields across an ultra-wide frequency range spanning megahertz to terahertz electromagnetic waves resonant with Rydberg atom dipole transitions. Here, we demonstrate an atomic millimeter-wave heterodyne receiver employing continuous-wave lasers stabilized to an optical frequency comb. We characterize the atomic receiver in the W-band at a signal frequency of f = 95.992 512 GHz and demonstrate a sensitivity of 7.9 μV/m/Hz with a linear dynamic range in power greater than 70 dB. We develop frequency selectivity metrics for atomic receivers and demonstrate their use in our millimeter-wave receiver, including signal rejection levels at signal frequency offsets Δf/f = 10−4, 10−5, and 10−6; 3, 6, 9, and 12-dB bandwidths; filter roll-off; and shape factor analysis. Our work represents an important advance toward future studies and applications of atomic receiver science and technology in weak millimeter-wave and high-frequency signal detection.
Abstract Terahertz heterodyne receivers with high sensitivity and spectral resolution are crucial for various applications. Here, we present a room-temperature atomic terahertz heterodyne receiver that achieves ultrahigh sensitivity and frequency resolution. At a signal frequency of 338.7 GHz, we obtain a sensitivity of 2.88 ± 0.09 μV⋅cm −1 ⋅Hz −1/2 for electric field measurements. The calibrated linear dynamical range spans approximately 89 dB, ranging from −110 dBV/cm to −21 dBV/cm. We demodulate a 400 symbol stream encoded in 4-state phase-shift keying, demonstrating excellent phase detection capability. By scanning the frequency of the local oscillator, we realize a terahertz spectrometer with Hz level frequency resolution. This resolution is more than two orders of magnitude higher than that of existing terahertz spectrometers. The demonstrated terahertz heterodyne receiver holds promising potential for working across the entire terahertz spectrum, significantly advancing its practical applications.
Atomic heterodyne dressed by a local oscillator resonant with Rydberg transitions allows high sensitivity and robust phase measurement of a microwave electric field, but it is typically limited to detection of discrete frequencies within the narrow bandwidth of Rydberg transitions. Here we demonstrate an atomic heterodyne scheme for continuous-frequency electric field measurement based on multilevel Rydberg atoms in a room-temperature vapor cell. Driven by two off-resonant microwaves acting as a tunable local oscillator field, the heterodyne receiver can retrieve the amplitude, phase, and frequency information of signal microwave in a continuous frequency band. In our experiment, the receiver achieves an electric field sensitivity of up to $1.5\phantom{\rule{0.2em}{0ex}}\ensuremath{\mu}\mathrm{V}\phantom{\rule{0.2em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}\phantom{\rule{0.2em}{0ex}}{\mathrm{Hz}}^{\ensuremath{-}1/2}$, 80-dB linear dynamic range, and over 1 GHz of continuous frequency range. We also demonstrate the reliable reception of continuously tunable phase-modulated carriers in the digital communication. This work will facilitate the application of atomic heterodyne in the areas such as radar technique, radio monitoring, and radio astronomy.
We demonstrate an atomic rf receiver and spectrum analyzer based on thermal Rydberg atoms coupled to a planar microwave waveguide. We use an off-resonant rf heterodyne technique to achieve continuous operation for carrier frequencies ranging from dc to 20 GHz. The system achieves an intrinsic sensitivity of up to $\ensuremath{-}120(2)$, dc coupling, 4-MHz instantaneous bandwidth, and over 80 dB of linear dynamic range. By connecting through a low-noise preamplifier, we demonstrate high-performance spectrum analysis with peak sensitivity of better than $\ensuremath{-}145\phantom{\rule{0.2em}{0ex}}\mathrm{dBm/Hz}$. Attaching a standard rabbit-ears antenna, the spectrum analyzer detects weak ambient signals including FM radio, AM radio, WiFi, and bluetooth. We also demonstrate waveguide-readout of the thermal Rydberg ensemble by nondestructively probing waveguide-atom interactions. The system opens the door for small, room-temperature, ensemble-based Rydberg sensors that surpass the sensitivity, bandwidth, and precision limitations of standard rf sensors, receivers, and analyzers.
While Rydberg atoms have shown tremendous potential to serve as accurate and sensitive detectors of microwaves and millimeter waves, their response is generally limited to a single, narrow frequency band around a chosen transition. As a result, their potential to serve as agile and wideband electromagnetic receivers has not been fully realized. Here we demonstrate the use of a mid-infrared, frequency agile optical frequency comb as the coupling laser for three-photon Rydberg atom electrometry. This approach allows for rapid switching between as many as seven individual Rydberg states, allowing for multichannel detection across a frequency range from 1 GHz to 40 GHz. The generality and flexibility of this method for wideband multiplexing is anticipated to have transformative effects in the field of Rydberg electrometry, paving the way for advanced information coding, arbitrary signal detection, and the simultaneous detection of ultra-broadband radiofrequency radiation. Rydberg atoms have the potential to serve as broadband receivers but require lasers with > 100 GHz scan ranges to observe multiple states. We bridge this major gap with an optical frequency comb for rapid preparation of over 7 Rydberg states.
Rydberg sensors offer a unique approach to radio-frequency (rf) detection, leveraging the high sensitivity and quantum properties of highly excited atomic states to achieve performance levels beyond classical technologies. Nonlinear responses and distortion behavior in Rydberg atom receivers are critical to evaluating and establishing performance metrics and capabilities such as spur-free dynamic range and tolerance to unwanted interfering signals. We report here on the measurement and characterization of nonlinear behavior and spurious response of a Rydberg atomic heterodyne receiver. Single-tone and two-tone testing procedures are developed and implemented for measurement of harmonic and intermodulation distortion in Rydberg atomic receivers based on multiphoton Rydberg spectroscopy and radio-frequency heterodyne signal detection and demodulation in an atomic vapor. For a predetermined set of atomic receiver parameters and rf carrier wave in the super high frequency band near-resonant to a cesium Rydberg transition, we measure and characterize atomic receiver selectivity, bandwidth, roll-off, compression point (P1dB), second-order (IP2) and third-order (IP3) intercepts, and spur-free dynamic range. Receiver intermodulation distortion is characterized for the case of an interfering signal wave applied at two frequency offsets relative to the near-resonant reference local oscillator, Δ F / F = 10 − 4 at 6 dB and 10 − 6 at 22 dB single-tone bandwidths, respectively. We observe that under suitable operating conditions the atomic receiver can exhibit a suppression of harmonic and intermodulation distortion relative to that of classical receiver mixer amplifiers.
Highly sensitive detection of microwave (MW) fields throughout ultra-wideband spectrum is always an important subject in metrology, electromagnetism and cosmology. Rydberg atomic electrometers, which implement electric field measurements by detecting the disturbance of atomic energy levels, have the potentials to breakthrough the sensitivity and size limits of conventional sensors. However, due to the discrete structure of the energy levels, current measurements can only exhibit high sensitivity at the discontinuous frequencies which correspond to certain transitions. In this work, by implementing energy level modulation of Rydberg atom through Zeeman effect, we achieve continuous highly sensitive MW fields detection within 1-40 GHz ultra-wideband spectrum where the detection sensitivity is roundly below 65 nV cm-1 Hz-1/2, which is 2-3 orders of magnitude lower than that of the state-of-the-art continuous measurement architectures. The proposed method is expected to expand the working bandwidth from MHz to THz and therefore greatly accelerate the practical applications in the areas of radar and electronic reconnaissance. Detecting microwave fields across an ultra-wideband spectrum is crucial for advancements in metrology, electromagnetism, and cosmology. Here, the authors utilize Zeeman effect modulation of Rydberg atoms to achieve continuous, highly sensitive detection from 1-40 GHz, significantly enhancing sensitivity and potentially transforming radar and electronic reconnaissance applications.