Rydberg quantum sensors offer the potential for capabilities inaccessible to classical systems. Here we perform simultaneous phase and amplitude sensing of five rf fields spanning 1.7 GHz to 116 GHz and implement a digital communications receiver.
Electric field sensors based on Rydberg atoms offer unique capabilities, relative to traditional sensors, for detecting radio-frequency (rf) signals. In this work, we demonstrate simultaneous demodulation and detection of five rf tones spanning nearly two decades (six octaves), from 1.7 GHz to 116 GHz. We show continuous recovery of the phase and amplitude of each tone and report on the sensitivity of the system and its bandwidth capabilities for multiband detection. We use these capabilities to demonstrate a digital communication protocol, simultaneously receiving on-off-keyed binary data from four bands spanning nearly one decade of frequency.
We report on the development of detection methods for amplitude and phase of pulsed radio-frequency (RF) electromagnetic fields with Rydberg atoms. We begin with an overview of the basic principles of Rydberg-atom-based sensing and measurement of RF electromagnetic fields. An overview of the underlying atomic physics and the method for amplitude as well as phase sensing of electromagnetic radiation with Rydberg atoms is provided. Atomic RF receivers using Rydberg atoms for analog and digital communications and sensing of modulated RF fields are discussed. Detection of pulse-modulated RF and time-domain RF pulse waveform imaging with a Rydberg-atom receiver are demonstrated. The transient response of the Rydberg-atom vapor to a modulated RF field is observed at the 10-nanosecond level, from which a new lower limit to the achievable instantaneous signal bandwidth of atomic RF receivers is established. Finally, we present and describe a new method to measure the phase of an RF field implemented to not require an RF reference wave. The method employs phase-coherent excitation pathways involving the optical fields in the atomic sensing medium with the signal RF field. The optical RF phase-sensing approach lends itself to the realization of atomic RF sensors, measurement and imaging devices that are relevant to applications in RF communications and sensing.
An antenna is a key component of E-field signal pickup. However, an antenna has major limitations due to the metal-based probes, the geometry it carries, and the use of metal transmission lines; this can lead to perturbations or disturbance of the fields which limits the precision for field sensing. Rydberg atoms such as Cesium (Cs) or Rubidium (Rb) are utilized for Rydberg sensing. This can be utilized over a large range of frequencies from DC MHz and THz upto (>100 GHz) to measure amplitude, polarization, power, phase, and Angle-of-Arrival of RF Efield. Rydberg sensor detection scheme provides a multitude of applications, including far field characterization using near field or subwavelength imaging, strong RF E-field measurements, weak field detections, mapping of microwave circuitry, Binary Phase Shift Keying (BPSK), Quadrature Amplitude Modulation (QAM) and Quadrature Phase Shift Keying (QPSK) signals, metrology, and radars. Recently, practical RF E-field probes such as the RFP and movable probe have been prototyped for application specific RF sensing and measurement needs, further, antenna and waveguide embedded Rydberg sensors have also been developed. Few limitations in the Rydberg sensing scheme are due to lasers, EIT line-width, earth magnetic effects, photodiode circuit noise, and vapor cell in-homogeneity. The purpose of the review is to brief about the thematic work done across the Rydberg atom domain and its applications as RF E-field sensors. The findings of this review indicate the advantages and applications of Rydberg atom sensing as well as the gaps and uncertainties the scheme carries.
With the escalating development of the quantum information technologies, the Rydberg atomic receiver has been envisioned as a promising alternative to its classical electronic counterparts, attracting extensive attentions from both physics and electronic engineering disciplines. By exploiting the electrical acuteness of Alkali atoms with diverse Rydberg energy states for electromagnetic field measurement, Rydberg atomic receiver is capable of surmounting the inherent limitations on the operating bandwidth and detection sensitivity of the classical electronic counterparts. Against this background, this article provides an extensive overview of Rydberg atomic communication and sensing from fundamental theory, critical technologies to practical implementations. Firstly, the milestones of the Rydberg atomic receiver evolution was introduced. Then we provide a clear understanding of Rydberg atomic receiver mechanisms from the perspective of classical communication and sensing, and highlight the unprecedented advantages over traditional electronic receivers as well as the technical challenges. Afterwards, necessary fundamentals are presented including the Rydberg atoms, typical non-coherent/coherent structures, and explicit experimental configurations, followed by discussions on state-of-the-art development of the Rydberg atomic receiver. Specifically, advancements on electric-field detection methods for accurate measurement of amplitude, phase, frequency and polarization, are extensively investigated. Based on the established methodologies, recent innovations in Rydberg atomic communication and sensing are reviewed, ranging from waveform design and array-based signal processing to radar applications like localization, imaging and remote sensing, with practical experimental results presented. Finally, we summarize the promising research trends around Rydberg atomic receiver.
Rydberg atom electric field sensors are projected to enable novel capabilities for resilient communications and sensing. This quantum sensor is small-size, highly sensitive, and broadly tunable, and it has the potential for performing precision vector electric field and angle-of-arrival measurements. While these atomic electric field sensors will not replace traditional receivers in commodity applications for RF signal reception, these sensors could be an enabling technology in niche application spaces. This review outlines the principles of operation of atomic electric field sensors and compares their performance capabilities to traditional RF receivers. It also highlights recent research and development efforts in atomic electric field sensing and identifies applications for which these sensors are projected to impact communications and remote sensing.